programme tuesday, july, 31

Tidalites 20128th International Conference

on Tidal Environments

Caen, France

July 31 - August 2

Abstract book

Acknowledgments

The organizing committee of Tidalites 2012 greatly thanks the following partnersfor their support:

The research Lab UMR M2CThe CNRS - INSUThe APGN (Association of the Geological Heritage of Normandy) The University of Caen - Basse NormandieThe University of RouenThe City of CaenThe Basse Normandie Regional CouncilThe Calvados Department CouncilThe Geological Society of France (SGF)The Association of French Sedimentologists (ASF)

We sincerely thank also the following additional partners for field trip organisation:

University of La Rochelle, UMR LIENSs, The Charente-Maritime Department Council (FT1)University of Angers, BIAF lab, LaSalle Beauvais School, MNHN (FT3)University of Lille 1, UMR Géosystèmes, Carrière Oscar Savreux (FT4)University of Caen, UMR M2C, Total, MINES ParisTech, Syndicat Mixte Mont Saint Michel (FT5)

Main organizing committee

The Tidalites 2012 conference is organized by the research laboratory

“Morphodynamique Continentale et Côtière”(CNRS - Universities of Caen Basse Normandie and Rouen)

Bernadette Tessier (general coordination)

Anthony Dubois (webmaster, data base)

Jacques Avoine, Olivier Dugué, Isabelle Neghaban, Marie-Pierre Bouet(financial management)

Valérie Casado, Isabelle Neghaban (secretariat)

Venue

Auditorium - Musée des Beaux-ArtsCaen Castle

PROGRAMME

TUESDAY, JULY, 31

Auditorium of the "Musée des Beaux-Arts", Caen Castle

8h00 - 9h00 - Registration and Poster installation

9h00 - 10h00 - Conference introduction

Chairman: Daidu FAN10h00 - BARTHOLDY Jesper, ERNSTSEN Verner B.

ON THE FORMATION OF RIPPLES AND DUNES

10h20 - FLOESER Goetz, BURCHARD Hans, RIETHMUELLER RolfOBSERVATIONAL EVIDENCE FOR THE INWARD TRANSPORT OF SUSPENDED MATTER BY ESTUARINE CIRCULATION IN THEWADDEN SEA

10h40 - WANG Ya PingSEDIMENT RESUSPENSION, FLOCCULATION AND SETTLING IN A MACROTIDAL ESTUARINE ENVIRONMENT

11h00 - LIU James T., CHEN Wayne, C.SEDIMENT TRANSPORT PATTERNS AND SOURCES IN A RIVER DELTA-TIDAL FLAT COMPLEX IN TAIWAN

11h20 - ALVAREZ Luis G., RAMIREZ RafaelFACTORS INFLUENCING SEDIMENT MOBILITY ON THE INTER-TIDAL FLATS OF THE UPPER GULF OF CALIFORNIA.

11h40 - CHANG TaesooBAEKSU OPEN-COAST TIDAL FLAT OF THE KOREAN WEST SEA COAST REVISITED: A DEPOSITIONAL MODEL AND ITSPRESERVATION POTENTIAL

12h00 - 14h00 - Lunch at the restaurant "Café Mancel"

Chairman: Kyungsik CHOI14h00 - JABLONSKI Bryce, DALRYMPLE Robert W.

SEDIMENTOLOGY OF A FLUVIALLY DOMINATED, TIDALLY INFLUENCED POINT BAR: THE LOWER CRETACEOUS MIDDLEMCMURRAY FORMATION, LOWER STEEPBANK RIVER AREA, NORTHEASTERN ALBERTA, CANADA

14h20 - PELLETIER Jonathan, ABOUESSA Ashour, DURINGER Philippe, SCHUSTER Mathieu, GHIENNE Jean-François, RUBINO Jean-LoupRHYTHMIC CLIMBING RIPPLES LAMINATION FROM MODERN (BAY OF THE MONT-SAINT-MICHEL, FRANCE) AND ANCIENT (DUR ATTALAH, PALEOGENE, LIBYA) TIDAL DEPOSITIONAL ENVIRONMENTS: DESCRIPTION, GENESIS, SIGNIFICANCE AND NEW CRITERIONFOR TIDAL EVIDENCE.

14h40 - REITH Geoff, DALRYMPLE Robert W., MACKAY Duncan, ICHASO AitorUNDERSTANDING THE DEPOSITION OF TIDALLY DEPOSITED MUDSTONES: AN EXAMPLE FROM THE TILJE FORMATION(JURASSIC), OFFSHORE NORWAY

15h00 - LEGLER Berit, JOHNSON Howard, HAMPSON Gary, MASSART Benoit, JACKSON Christopher, JACKSON Matthew, EL-BARKOOKYAhmed, RAVNAS RodmarFACIES MODEL OF A FINE-GRAINED, TIDE-DOMINATED DELTA: LOWER DIR ABU LIFA MEMBER (EOCENE), WESTERN DESERT,EGYPT

15h20 - QUIJADA I. Emma, SUAREZ-GONZALEZ Pablo, BENITO M. Isabel, MAS RamónTIDE-INFLUENCED FLUVIAL-DELTAIC SEDIMENTS VERSUS CONTINENTAL SANDY-MUDDY FLAT DEPOSITS: EVIDENCE FROM THEHUERTELES FM (EARLY CRETACEOUS, N SPAIN)

15h40 - LONGHITANO Sergio, CHIARELLA Domenico, SPALLUTO LuigiTIDAL FACIES IN SILICICLASTIC, CARBONATE AND MIXED MICROTIDAL ANCIENT SYSTEMS OF SOUTHERN ITALY

Coffee break and poster session

Chairman: Jesper BARTHOLDY17h00 - MARGOTTA José, TRENTESAUX Alain, TRIBOVILLARD Nicolas, ABRAHAM Romain

FRENCH FLANDERS FIELDS: DECIPHERING THE HOLOCENE SEDIMENTARY HISTORY OF THE COASTAL PLAIN OF NORTHERNFRANCE

17h20 - JOHANNESSEN Peter N., NIELSEN Lars Henrik, MØLLER Ingelise, NIELSEN Lars Henrik, ANDERSEN Thorbjørn Joest, PEJRUPMortenTHE SEDIMENTARY DEVELOPMENT OF A HOLOCENE TO RECENT BARRIER ISLAND, DANISH WADDEN SEA

17h40 - FRUERGAARD Mikkel, ANDERSEN Thorbjørn Joest, NIELSEN Lars Henrik, JOHANNESSEN Peter N., PEJRUP MortenEVOLUTION AND STRATIGRAPHY OF A HOLOCENE MICRO-TIDAL BARRIER SYSTEM IN THE NORTHERN WADDEN SEA

18h00 - WANG Yunwei, YU Qian, GAO ShuEFFECTS OF GRAIN-SIZE SORTING ON THE SCALE-DEPENDENCES OF EQUILIBRIUM MORPHOLOGY OF BACKBARRIER TIDALBASINS

18h30 - 20h00 - Conference cocktail

WEDNESDAY, AUGUST, 01


Chairman: Burghard FLEMMING08h30 - TRENTESAUX Alain, ABRAHAM Romain, BAFFREAU Alexandrine, DAUVIN Jean-Claude, LOZACH Sophie, MALENGROS Deny,

POIZOT EmmanuelMARINE HABITAT CLASSIFICATION: A PLURIDISCIPLINARY APPROACH IN A HIGH MACROTIDAL ENVIRONMENT. THE CASE OF THEENGLISH MEDIAN CHANNEL

08h50 - DAUVIN Jean-Claude, BERYOUNI Khadija, LOZACH Sophie, MEAR Yann, MURAT Anne, POIZOT EmmanuelLIVE UNDER TIDAL REGIME: THE ROLE OF THE BRITTLE-STAR OPHIOTHRIX FRAGILIS BEDS FROM THE EASTERN BAY OF SEINE INTHE FINE PARTICLE DEPOSIT-SUSPENSION MECHANISMS

09h10 - BARTHOLOMAE Alexander, HOLLER PeterANALYSIS OF SUBTIDAL HABITATS IN THE GERMAN WADDEN SEA ON THE BASE OF HYDRO-ACOUSTIC REMOTE SENSING DATA

09h30 - BAUCON Andrea, FELLETTI FabrizioA QUANTITATIVE TOOL FOR THE ICHNOLOGICAL ANALYSIS OF TIDAL ENVIRONMENTS: THE ICHNOGIS METHOD

09h50 - VALERIUS Jennifer, MILBRADT Peter, VAN ZOEST Michael, ZEILER ManfredDEVELOPMENT OF A SEABED MODEL FOR ANALYZING SEDIMENT AND MORPHODYNAMIC PROCESSES IN THE GERMAN BIGHT(NORTH SEA)


Chairman: Robert W. DALRYMPLE11h00 - ARCHER Allen

COMPARISON OF HYPERTIDAL SYSTEMS IN EUROPE, SOUTH AND NORTH AMERICA

11h20 - FURGEROT Lucille, MOUAZE Dominique, TESSIER Bernadette, HAQUIN Sylvain, PEREZ Laurent, VIEL FélixINFLUENCE OF THE TIDAL BORE ON SEDIMENT TRANSPORT IN THE MONT-SAINT-MICHEL ESTUARY, NW FRANCE.

11h40 - FAN Daidu, SHANG Shuai, TU Jinbiao, CAI Guofu, WU YijingSEDIMENTATION PROCESSES AND SEDIMENTARY CHARACTERISTICS OF TIDAL BORES IN THE QIANTANG ESTUARY,EAST-CENTRAL CHINA

12h00 - CHAMIZO BORREGUERO M., MELENDEZ N., DE BOER PoppeTIDAL BORE INDUCED SEDIMENTS IN INCISED VALLEYS, UTRILLAS FM, ALBIAN, SW IBERIAN RANGES, SPAIN

12h20 - DE BOER PoppeMILANKOVITCH-SCALE ORBITALLY FORCED TIDAL CYCLICITY

12h40 - 14h30 - Lunch at the restaurant "Café Mancel"

Chairman: Eric CHAUMILLON14h30 - GONG Wenping

ASSESSMENT OF SILTATION AT THE DREDGED CHANNEL IN THE HUANGMAOHAI ESTUARY, PEARL RIVER DELTA, CHINA

14h50 - GLUARD Lucile, LEVOY FranckTHE 18.6 YEAR TIDAL CYCLE INFLUENCE ON THE COUESNON RIVER BEHAVIOUR, MONT-SAINT-MICHEL BAY (FRANCE)

15h10 - CHOI Kyungsik, HONG Chang Min, OH Chung Rok, JUNG Jae HoonMORPHODYNAMICS OF TIDAL CHANNELS IN THE MACROTIDAL YEOCHARI TIDAL FLAT, GYEONGGI BAY, WEST COAST OF KOREA:IMPLICATION FOR THE ARCHITECTURE OF INCLINED HETEROLITHIC STRATIFICATION

15h30 - HERRLING Gerald, WINTER ChristianTHE EFFECT OF HIGH-ENERGY EVENTS ON EBB-TIDAL DELTA SEDIMENTOLOGY AND MORPHOLOGY – A PROCESS-BASED MODELSTUDY

15h50 - FERRET Yann, LE BOT Sophie, LAFITE Robert, BLANPAIN Olivier, GARLAN ThierryINFLUENCE OF TIDE VS WAVE ON SEDIMENT DYNAMICS AND DUNE INTERNAL ARCHITECTURE ON A MACROTIDAL INNERCONTINENTAL SHELF (EASTERN ENGLISH CHANNEL).


Chairman: Poppe DE BOER17h00 - YU Qian

MODELING THE FORMATION OF A SAND BAR WITHIN A LARGE FUNNEL-SHAPED, TIDE-DOMINATED ESTUARY: QIANTANGJIANGESTUARY, CHINA

17h20 - CHAUMILLON Eric, FENIES Hugues, BILLY Julie, BREILH Jean-FrançoisTIDAL AND CLIMATE CONTROLS ON THE MORPHOLOGICAL EVOLUTIONS AND THE INTERNAL ARCHITECTURE OF A TIDAL BAR:THE PLASSAC TIDAL BAR IN THE BAY-HEAD DELTA OF THE GIRONDE ESTUARY.

17h40 - SAITO YoshikiMONSOON-CONTROLLED DELTAIC SEDIMENTATION IN A TIDE-DOMINATED SETTING: EXAMPLES FROM MEGA-DELTAS IN ASIA

18h00 - MASSUANGANHE Elidio, BANDEIRA Salomao, WESTERBERG Lars-OveIMPACTS OF FLOODS AND CYCLONES ON MANGROVE OVER A SECTOR OF THE SAVE RIVER DELTA PLAIN, MOZAMBIQUE.

18h20 - MAKINO Yasuhiko, ARAI Shota, ITO Takashi, NANAYAMA FutoshiEFFECT OF THE 2011 GIANT TSUNAMI ON A SANDY BEACH AT OARAI, EASTERN JAPAN

18h45 - Departure from the conference place for the Conference Dinner (by bus)

THURSDAY, AUGUST, 02


Chairman: Jean-Yves REYNAUD08h30 - CHOI Kyungsik, JUNG Jae Hoon, JO Joo Hee

RAPID INFILLING OF MACROTIDAL ESTUARY DURING EARLY HOLOCENE IN YEOCHARI TIDAL FLAT, GYEONGGI BAY, WEST COASTOF KOREA

08h50 - KITAZAWA ToshiyukiTIDAL RAVINEMENT SURFACE IN A TIDE-DOMINATED ESTUARY: PLEISTOCENE NHA BE ESTUARY, SOUTHERN VIETNAM.

09h10 - EKWENYE Ogechi, NICHOLS Gary, NWAJIDE Sunny, OBI GordianDEPOSITIONAL ARCHITECTURE AND ICHNOLOGY OF THE TIDALLY-INFLUENCED ESTUARINE SYSTEM OF THE EOCENE AMEKIGROUP

09h30 - DALRYMPLE Robert W., JAMES Noel, SEIBEL Meg, BESSON David, PARIZE OlivierWARM-TEMPERATE, MARINE, CARBONATE SEDIMENTATION IN AN EARLY MIOCENE, TIDE-DOMINATED, INCISED VALLEY;PROVENCE, SE FRANCE

09h50 - ILGAR Ayhan, TIMUR Erol, KARAKUS Erhan, KAYA Serap, TURKMEN BanuLATE MIOCENE INCISED VALLEY-FILL IN EASTERN TAURIDES, TURKEY: DEPOSITIONAL EVOLUTION IN RESPONSE TO SEA-LEVELCHANGE AND DEPOSITIONAL PROCESSES


Chairman: Yoshiki SAITO11h00 - YIN Yong

THE LATE PLEISTOCENE–HOLOCENE STRATIGRAPHY AND SEDIMENTARY ENVIRONMENT OF THE TIDAL RADIAL SAND RIDGESYSTEM, JIANGSU OFFSHORE, SOUTH YELLOW SEA

11h20 - MICHAUD Kain, DALRYMPLE Robert W.TRANSGRESSIVE, HEADLAND-ATTACHED TIDAL SAND RIDGES IN THE RODA FORMATION, NORTHERN SPAIN

11h40 - PELLETIER Jonathan, ABOUESSA Ashour, DURINGER Philippe, SCHUSTER Mathieu, RUBINO Jean-LoupTHE GEOLOGICAL RECORD OF TIDAL DYNAMIC: DIVERSITY OF ASSOCIATED DEPOSITS AND MULTI-SCALE CYCLES FROM THEDUR AT TALAH FORMATION (UPPER EOCENE, SIRT BASIN, LIBYA)

12h00 - CHOI Kyungsik, STEEL Ronald, OLARIU CornelTIDAL RHYTHMITES IN THE UPPER CRETACEOUS NESLEN FORMATION, UTAH, USA: THEIR IMPLICATIONS FOR THESEDIMENTOLOGY AND STRATIGRAPHIC ARCHITECTURE OF TIDAL-FLUVIAL CHANNEL

12h30 - 14h00 Lunch at the restaurant "Café Mancel"

Chairman: Allen ARCHER14h30 - WEILL Pierre, MOUAZE Dominique, TESSIER Bernadette

INTERNAL ARCHITECTURE AND EVOLUTION OF BIOCLASTIC BEACH RIDGES IN A MEGATIDAL CHENIER PLAIN: WAVE FLUMEEXPERIMENTS AND FIELD DATA

14h50 - REYNAUD Jean-Yves, RUBINO Jean-Loup, PARIZE Olivier, DALRYMPLE Robert W., VENNIN Emmanuelle, FERRANDINI Michelle,FERRANDINI Jean, ANDRE Jean-Pierre, TESSIER Bernadette, JAMES NoelOFFSHORE TIDAL BIOCLASTIC BODIES IN EPEIRIC SEAS: MIOCENE EXAMPLES FROM SE FRANCE AND CORSICA

15h10 - FLEMMING Burghard W.THE ORDOVICIAN TABLE MOUNTAIN GROUP, SOUTH AFRICA: THE TIDAL DEPOSIT THAT NEVER WAS

15h30 - SUAREZ-GONZALEZ Pablo, QUIJADA I. Emma, BENITO M. Isabel, MAS RamónDO STROMATOLITES NEED TIDES TO TRAP OOIDS? INSIGHTS FROM THE COASTAL-LAKE CARBONATES OF THE LEZA FM (EARLYCRETACEOUS, N SPAIN).

15h50 - ILGAR Ayhan, KARAKUS Erhan, ESIRTGEN TolgaTHE VARIABILITY OF ESTUARINE DEPOSITS IN A MICROTIDAL SETTING OF LATE MIOCENE MEDITERRANEAN (EASTERN TAURIDES,TURKEY): CONTROLLING FACTORS ON DEPOSITION

Last coffee break and poster session

POSTERS

BARRIOS Edixon JoseSEDIMENTOLOGICAL MODEL FOR C-4 RESERVOIR FROM VLA6/9/21 AREA, BASED ON INFORMATION OF CORE INTERPRETATION ANDCOMPARISON WITH THEORETICAL MODELS DEPOSITED UNDER SIMILAR SEDIMENTOLOGICAL CONDITIONS

BAUCON Andrea, FELLETTI Fabrizio“DEEP TIME ON A TIDAL FLAT”: THE ANCESTRAL ICHNOASSOCIATIONS OF THE MODERN GRADO LAGOON (NORTHERN ADRIATIC, ITALY)

CHANG Taesoo, KIM Jincheol, YOO Dong-GeunLATE QUATERNARY STRATIGRAPHIC EVOLUTION OF BAEKSU OPEN-COAST TIDAL FLAT, WEST COAST OF KOREA: REGIONALUNCONFORMITY-BOUNDED TWO TIDAL DEPOSITS

DIEZ-CANSECO Davinia, BENITO M. Isabel, DIAZ-MOLINA Margarita, KALIN OttoTIDAL INFLUENCE IN THE ‘LOWER RED UNIT’ OF THE TREMP FM IN SOUTH-CENTRAL PYRENEES (LATE CRETACEOUS-TERTIARY)

GUGLIOTTA Marcello, FLINT Stephen, HODGSON David, VEIGA GonzaloSEDIMENTOLOGY AND SEQUENCE STRATIGRAPHY OF THE FLUVIAL-TO-TIDAL TRANSITION ZONE IN THE UPPER LAJAS FORMATION(NEUQUEN BASIN, ARGENTINA)

HUSTELI Berit, JENSEN Maria, OLAUSSEN SnorreTIDALLY RELATED HETEROGENITIES IN SANDBODIES SOUGHT PARAMETERIZED FOR REFINED RESERVOIR MODELLING

JAMET Guillaume, DUGUE Olivier, DELCAILLAU Bernard, CLIQUET DominiqueTHE TIDALLY-INFLUENCED RIVER DEPOSITS OF THE PLEISTOCENE SEINE SYSTEM: THE EXAMPLE OF THE TOURVILLE-LA-RIVIERETERRACE (NW FRANCE)

KURCINKA Colleen, ICHASO Aitor, DALRYMPLE Robert W.TIDAL DELTAS IN THE LAJAS AND TILJE FORMATIONS: TIDE-DOMINATED OR TIDE-INFLUENCED?

LE BOT Sophie, BERTEL F, LANGLOIS Estelle, FOREY Estelle, MEIRLAND Antoine, LAFITE RobertLITTORAL SEDIMENTATION WITHIN SPARTINE AND OBIONE COMMUNITIES IN THE SOMME ESTUARY (EASTERN ENGLISH CHANNEL).PRELIMINARY RESULTS

LEMOINE Maxence, DELOFFRE Julien, LAFITE Robert, LESOURD Sandric, LESUEUR Patrick, CUVILLIEZ Antoine, FRITIER Nicolas, MASSEINicolasRHYTHMITES PRESERVATION IN MACROTIDAL ESTUARINE ENVIRONMENTS: FROM UPSTREAM TO DOWNSTREAM ESTUARY

LOZACH Sophie, ABRAHAM Romain, BAFFREAU Alexandrine, DAUVIN Jean-Claude, MALENGROS Deny, POIZOT Emmanuel, TRENTESAUXAlainBENTHIC HABITAT DIVERSITY IN COARSE SEDIMENT UNDER HIGH MACROTIDAL ENVIRONMENT

MAKINO YasuhikoSEDIMENTATION OF THE 2011 GIANT TSUNAMI ON A SANDY BEACH ON THE PACIFIC COAST OF EASTERN JAPAN

PARK Soo ChulLATE QUATERNARY STRATIGRAPHY AND MORPHODYNAMICS OF MACROTIDAL SAND BODIES IN THE WESTERN COAST OF KOREA

ROSSI Valentina, STEEL Ronald, OLARIU Cornel, LEVA LOPEZ JulioCOMPOUND TIDAL DUNES IN THE NEUQUEN JURASSIC RIFT BASIN

SCASSO Roberto, CUITIÑO José Ignacio, DOZO Teresa, BOUZA PabloMEANDERING TIDAL CHANNEL DEPOSITS IN THE FLUVIAL-TIDAL TRANSITION OF A MIOCENE ESTUARY IN PATAGONIA

SON Chang Soo, BARTHOLOMAE Alexander, FLEMMING Burghard W., CHUN Seong Soo, LEE In TaeTHE VARIATION OF THE SEDIMENTARY FACIES ON JADEBUSEN TIDAL BASIN IN GERMANY: SURFACE SEDIMENTS AND SEDIMENTARYSTRUCTURES

TANAKA AkikoCOASTAL MONITORING USING L-BAND SYNTHETIC APERTURE RADAR (SAR) IMAGE DATA IN THE MEKONG AND HUANGHE (YELLOWRIVER) DELTA AREAS

TESSIER Bernadette, BILLEAUD Isabelle, SORREL PhilippeSEDIMENTARY RECORDS OF CLIMATE CHANGES IN MACROTIDAL TIDE-DOMINATED ESTUARIES

VREL Anne, BOUST Dominique, LESUEUR Patrick, COSSONNET Catherine, DELOFFRE Julien, DUBRULLE-BRUNAUD Carole, MASSEINicolas, ROZET Marianne, SOLIER Luc, THOMAS SandrineTIDAL ASYMMETRY: THE USE OF ARTIFICIAL RADIONUCLIDES IN SEDIMENTS (THE SEINE ESTUARY, FRANCE)

WANG Dong, SONG Shengli, DING Hao, WU Jichun, ZHU Qingping, WANG LingHYDROLOGIC CHARACTERISTICS OF THE YELLOW RIVER MOUTH, CHINA

ZHANG Jicai, HUGHES Joseph, WANG Ping, HORWITZ MarkTHE VARIATIONS OF SALINITY AND STRATIFICATION FOR MICRO-TIDAL AND MANGROVE-COVERED FROG CREEK SYSTEMS, FLORIDA

ABSTRACTS

Tidalites 2012, 8th International Conference on tidal environments, Caen, France – Abstract book

FACTORS INFLUENCING SEDIMENT MOBILITY ON THE INTER-TIDAL FLATS OFTHE UPPER GULF OF CALIFORNIA

Luis G. ALVAREZ, Rafael RAMIREZ

CICESE, Carretera Ensenada-Tijuana no. 3918, Zona Playitas, 22860, Ensenada, Mexico,[email protected]

The northwest end of the Gulf of California, north of 31º N, is known as the Upper Gulf ofCalifornia (UGC). It is a semi-enclosed shallow basin, surrounded by arid alluvial plains andpiedmont deposits. This high-energy macro-tidal sea has semi-diurnal tides with range 7-8 mduring springs, and currents 1-3 m/s. Damming and diversion of the Colorado River havereduced freshwater and sediment supply to the UGC by more than 95% for over a century. Onthe west coast, an extensive coastal plain of tidal flats extends from high tide to about 12 belowmean sea level. The intertidal flats are drained by numerous dendritic, linear, and evenmeandering channels. Sediments are mainly reddish-brown mud. Sand is restricted to intertidalsand flats, tidal channels and a narrow belt of steep beaches ((Thompson, 1969; Schreiber, 1969;Meckel, 1975; Baba, et al., 1991).

Currents, tides, sediment properties and suspended sediment were measured on theintertidal flats during five short-term (1-3 days) time series in 2001 and 2008-2011. The aim wasto identify for the first time the processes that dominate sediment transport.

During spring tides, exposed intertidal flats are more that 5 km wide at the northwesternend of the UGC, decreasing to widths of ~1 km at the southern part, where the observationswere made. The main morphological elements at the observation site are low-relief (<0.5m) sandbars 100-300 m long, tidal drainage channels, and wide mud flats sheltered by the sand bars.Field measurements of the erosion threshold of surface sediments yielded 1-1.4 Pa for mediumsands, 0.5-0.6 Pa for very fine sand, and more spread (0.7 – 1.4 Pa) and generally higherthreshold for the sand-mud mixtures. Sediment texture and morphology suggest that the intertidalflats are wave-dominated, rather than tide-dominated. Tidal currents are only ~ 0.1 m/s on thelower inter-tidal flats while near-bed currents induced by 3-5 sec waves, 0.5-0.8 m high, canreach 0.4 m/s. Currents and suspended sediment (SS) concentration data show the developmentof a turbid tidal edge during ebb and flood tide. At the tidal edge, maximum SS concentration ina near-bed turbid layer reaches ~400 mg/l, under the prevailing wind and wave conditions. Undermoderate wind events ( ~8 m/s), maximum near-bed SS concentration can attain 800 mg/l.Suspended sediment concentration 1 m above the bed is lower by a factor of 2 to 10.

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Study site.

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COMPARISON OF HYPERTIDAL SYSTEMS IN EUROPE, SOUTH AND NORTHAMERICA

Allen ARCHER

KANSAS STATE UNIVERSITY, Department of Geology, 66506, Kansas, Us, [email protected]

Hypertidal ranges exceed 6 m and can range upwards to 15 m and potentially higher. Herein a comparison is made among systems that have the highest recognized tidal ranges onEarth. Settings in Europe include Bristol Bay and the Severn River estuary, southwestern UKand Mont-Saint-Michel Bay in Normandy, France. In South America, hypertidal ranges occurwithin tidal estuaries of Patagonia (southeastern portion of the Atlantic coast of Argentina). InNorth America hypertidal systems include: Turnagain Arm within Cook Inlet in south-centralAlaska, USA, Leaf Lake in Ungava Bay, northern Quebec, Canada and the Salmon River estuaryin the Bay of Fundy, Nova Scotia, Canada.

When compared to micro-, meso- or macrotidal coasts, hypertidal systems are extremelyrare. Hypertidal systems, however, do have enormous tidal ranges coupled with a tremendouspotential for high rates of sedimentation and erosion. A complete understanding of the dynamicsof these extreme systems is important for at least two reasons. First, they serve as modernanalogs for ancient systems that were formed with extremely dynamic tidal systems. In addition,from a more pragmatic standpoint, tidal power is a relatively untapped nonpolluting andrenewable source of energy. Currently operational tidal-power stations have been constructedentirely within hypertidal coastal settings. It is highly plausible that future developments will alsobe concentrated in hypertidal coastal settings.

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SEDIMENTOLOGICAL MODEL FOR C-4 RESERVOIR FROM VLA6/9/21 AREA,BASED ON INFORMATION OF CORE INTERPRETATION AND COMPARISON WITH

THEORETICAL MODELS DEPOSITED UNDER SIMILAR SEDIMENTOLOGICALCONDITIONS

Edixon Jose BARRIOS

PDVSA, Calle 77 Edificio 5 de Julio, 4002, Las Laras, Venezuela, [email protected]

Sedimentary environments defined for a specific reservoir, are the result of theinterpretation of data extracted from cores, cut in intervals with economic interest specifically onVLA6/9/21 area C-4 and C- 5 reservoirs from Misoa Formation have been studied and sittedwith the models built in neighboring areas. A well sedimentological model will be the result ofgeological and coherent integration of information provided by cores and channel samples and /or wall, biostratigraphy, well logs, information about deepmeters and image logs and evenengineering reservoir and then checked against all the models, which in turn will serve as inputfor the construction of other models such as geostatistics and simulation.

Throughout history, Geologists in pro of creating a model according to the reality ofreservoir, they have been required to propose models with poor or not information about coresand when they exist, in some cases with poor data or it´s has been recovered in sandy sectionsonly.

In recent studies in the area VLA6/9/21 was achieved taking into account the core data technically to support possible tidal influence for this reservoir in based of the presence ofsedimentary structures, biostratigraphy and with the comparison with others model was proposeda model with deltaic sedimentation and tidal influences for the units C-4 and C5 based on theidentification and recognition of distinctive features such as double-layer structures of clay, conecone structure, pairs of clay, together with other data will be the ideal complement to think that thearea at some point in geological time was under the influence of sedimentary processesassociated with tides. In other way, several studies have mentioned possible presence of anestuary as a sedimentary behavior as responsability of sedimentation. It´s important to highlightthat an estuary extends from the maximum bound of tidal influence zone to maximum bound of coastal processes influence of mouth, In some cases, it´s so difficult to difference where thefluvial action begins and where ends.

An estuary is defined as a coastal body of water semi-closed connected to open sea andinside which there are water mixtures of different salinities, from the sea and the continent;enough reason to avoid defining sedimentary environments of a region without having enoughinformation. If we consider that this area represent only a little part about all basin and in thesame way the answer of well log it´s show us heterogeneities in all of them, It´s neccesary tohighlight that Misoa Formation involve episodes of complex sedimentation, where is so difficult torecognize and identify a sedimentological model without uncertainty.

Complex systems like this are so linked and depend on the transgressive periods because if in a delta occurs a transgression it´s could become an estuary, Similarly, falls in the eustaticlevel in an estuary, will make it a prograding system (under certain parameters such as rateaccommodation, sediment supply, etc) therefore would be having like a delta.

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Escalona, A. and Mann, P. Sequence-stratigraphic, analisys of Eocene clastic foreland basin deposits incentral Lake Maracaibo using high-resolution well correlation and 3D seismic data: AAPG, April 2006, v 90,N°-4.Galloway, W. and Hobday, D. Terrigenous clastic depositional system, Springer-Verlag, Berlin 1996.Galloway, W,.Genetic stratigraphic sequences in basic analysis: I Arquitecture and genesis of floddingsurface bounded depositional units:, AAPG Bulletin, February 1989.Gonzalez de Juana, C., J. Azorena y X. C. Picard (1980) Geología de Venezuela y de sus cuencaspetrolíferas, Foninves, Caracas.Pettijohn, F.; Potter, P.; Siever, R. Sand and Sandstones. 1987, Springer- Verlag, New York, Inc., 2thedition.

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ON THE FORMATION OF RIPPLES AND DUNES

Jesper BARTHOLDY, Verner B. ERNSTSEN

GEOLOGICAL SURVEY OF DENMARK AND GREENLAND, Oester Voldgade 10, 1350, Copenhagen,Denmark, [email protected]

Ripples and dunes are commonly distinguished on the basis of their scaling or not-scalingwith flow depth as well as dimensional criteria such as wavelength. Ripples are regarded asindependent of water depth while dunes are generally considered to scale with depth. The simplefact that compound dunes exist contradicts the depth-scaling argument. If the largest compounddunes scale with water depth, where does that leave the smaller, superimposed ones? And, ifthese scale with water depth, how can the compound dunes be orders of magnitude larger? Toovercome this contradiction, it has sometimes been argued that the smaller superimposed dunesscale with boundary layers related the larger compound bedforms, also this can be disproved bymeans of examples, e.g lower right of Fig. 1 where the large compound features are missing.

Numerous experiments in small laboratory flumes the world over have demonstrated thatripples are not always independent of water depth. In terms of their size, all flow-transversebedforms generated in small demonstration flumes with depths < 0.1 m are by definition ripples inspite of the fact that they clearly scale with water depth, as revealed by contracting water surfacesover their crests. As a consequence, the criteria by which ripples and dunes are supposed to bedistinguished are inherently suspect. Fact is that if flow depth is small enough, any bedform willscale with it, simply because depth limitation forms a natural upper boundary, and serves as anupper limit for bedform growth of any kind. In research flumes, the maximum water depth istypical less than 0.5 m. As a result, dune heights will remain smaller than about 15 cm. It istherefore not surprising that the largest bedforms in flume studies are always found to scale withflow depth. By contrast, dunes observed on the ocean floor at depths of 10s-1000s of metersexhibit a wide range of sizes. These must evidently be controlled by factors other than waterdepth. The only meaningful explanation is that dunes are scaled with the mutual relationshipbetween flow conditions and form response. These matters are examined on the basis of theoryand experiments, and it is demonstrated that bedforms result from self-organizing processesacting across the interface between sand and water forming boundary layers directly dependenton bedform height.

7


Multibeam registration of bedforms in the tidal inlet Knudedyb on the Danish west coast. The colors indicatethe approximate water depth relative to the mean water level. The tidal range in the inlet is 1.7 m. Themean grain-size in the center of the channel varies from a maximum of about 0.650mm at the bedform

crest to a minimum of about 0.200 mm in the troughs.

8


ANALYSIS OF SUBTIDAL HABITATS IN THE GERMAN WADDEN SEA ON THEBASE OF HYDRO-ACOUSTIC REMOTE SENSING DATA

Alexander BARTHOLOMAE, Peter HOLLER

SENCKENBERG, Suedstrand 40, 26382, Wilhelmshaven, Germany, [email protected],[email protected]

Since the Wadden Sea area was awarded a World Nature Heritage the public pressure ofhabit protection grows distinctly. The European Water Framework Directive requires a standardmapping of marine habitats. Therefore quality tools to assess the recent stage and to monitorchanges in the near future are needed. For the intertidal area airborne laserscanning andSynthetic Aperture radar (SAR) are the state of art (Bartholdy & Folving 1986, Brzank et al. 2008).In contrast to the intertidal area, optical approaches are less successful to cover the subtidal partof the Wadden Sea area. High suspension load coupled with less visibility reduce and /or inhibitwide-spread used optical based techniques. To compensate this deficit, alternative techniqueshave to be developed. From the pelagic area the quite well-known hydro-acoustic devices arenow more and more adapted to shallow water operation (Hughes-Clarke et al. 1996).

To work out standard procedures for sub-aquatic monitoring, three hydro-acoustic deviceswere tested to their resolution, their redundancy and their value of benefit detecting habitats in athree year lasting case study in the East Frisian Wadden Sea (Bartholomae et al 2011). In orderto find out which are the system-specific limitations like foot-print sizes and coverage, seven testareas in water depths between 5 m to 15 m were simultaneously surveyed using singlebeamechosounder (SBS) (200 kHz), multibeam echosounder (MBES) (455 kHz) and Sidescan sonar(SSS) (380 kHz). Based on the principle of acoustic respond the return signals were analysedwith acoustic seabed classification tools to determine the different characteristics of seafloorroughness. Up to five major acoustic classes have been specified. These classes cover seasurface sediments consisting of sand, shells debris, gravel, less mud and infrequently some peatat the seven study sites in the East Frisian backbarrier tidal flats. Repetitive surveys were carriedout to investigate system specific variations and natural changes in the complex spatial pattern ofthe subtidal habitats. Based on the given technical specifications of the different acoustic devicesthe influence of footprint sizes was tested by applying different grid sizes in the data analysis. Inorder to generate similar footprint sizes for a water depth of 15m MBES data were calculated on agrid sizes of 33x17 pixel (0.9m x 3.7m ; 3.3 m²), SSS data with 17x9 pixels (0.8m x 2.4m ;1.92m²) which correspond to a SBS footprint of 2.98 m². This already limits the minimum waterdepth of operation for the oblique-angled geometries.

The spatial distribution of the acoustic classes was tested by means of confidence levels ofacoustic similarities within the classification results of each system as well as between thedifferent acoustic devices. The fit of ground truth data to acoustic classes and the importance ofthe sediment specific surface roughness was tested by multidimensional scaling (MDS) andcluster analysis for bulk sediment composition and for the individual grain size distributions.Seasonal up to annual scaled times series were analysed with regard to habitat dynamics inexposed and sheltered areas of the Wadden Sea.

The results of the case study are summarized in a comprehensive report which discussesthe differences in backscatter based classification, local effects of natural and human impact tothe specific sites and the system specific differences such as working-frequencies and footprintgeometry.

In general the backscatter based systems are much more sensitive to changes in surfaceroughness than of the sediment type itself. For the sediments in the Wadden Sea this sensitivitystarts getting more relevant in dependence of the footprint size, the effect of smoothing decreasesin shallower water depth.

Results of habitat distributions and their site dependent differences and the system relatedlimitation will be discussed in a condensed way.

9


Ground truthing results for the classification of multi-beam echosounder data (5 classes) from the locationOtzumer Balje

Bartholdy, J. and Folving, S. 1986. Sediment classification and surface type mapping in the DanishWadden Sea by remote sensing. Netherlands Journal of Sea Research, 20 (4), 337-345.Bartholomä, A., Holler, P., Schrottke, K. and Kubicki, A. (2011) Acoustic habitat mapping in the GermanWadden Sea – Comparison of hydro-acoustic devices. J. Coast. Res.,Spec. Iss. 64, ICS 2011 Proc., 1-5. Brzank, A., Heipke, Ch., Goepfert, J. and Soergel, U., Aspects of generating precise digital terrain modelsin the Wadden Sea from lidar–water classification and structure line extraction. Journal of Photogrammetryand Remote Sensing, 63 (5), 510-528.Hughes-Clarke, J.E., Mayer, L.A. and Wells, D.W., 1996. Shallow water imaging multibeam sonars: A newtool for investigating seafloor processes in the coastal zone and on the continental shelf. MarineGeophysical Research, 18, 607-629.

10


“DEEP TIME ON A TIDAL FLAT”: THE ANCESTRAL ICHNOASSOCIATIONS OF THEMODERN GRADO LAGOON (NORTHERN ADRIATIC, ITALY)

Andrea BAUCON, Fabrizio FELLETTI

DIPARTIMENTO DI SCIENZE DELLA TERRA, Università di Milano, 20133, Milano, Italy,[email protected]

The Northern Adriatic Sea is a shallow, semi-enclosed sea lying on continental crust, beingan ideal model for past epicontinental seas (Fig. 1A). In addition, recent studies suggests that itsbenthic subtidal ecosystem closely resembles Paleozoic-style ecology (McKinney, 2003, 2007;McKinney and Hageman, 2006). Although some objections were raised on the mentionedecological aspects (Zuschin and Stachowitsch, 2009), the Northern Adriatic Sea is unanimouslyconsidered one of the few modern epicontinental seas comparable to some Paleozoic–Mesozoicshelves (McKinney, 2003, 2007; McKinney and Hageman, 2006; Zuschin and Stachowitsch,2009).

The Grado-Marano lagoon is the northernmost transitional system of this peculiargeobiologic scenario. Here, barrier-island systems with vast tidal flats support a complex mosaicof sedimentary environments, which offer varied habitats for tracemaking organisms (Baucon,2008). Intriguingly, the intertidal flats are characterized by ancestral bioturbation styles coexistingwith modern, Thalassinoides-dominated ones:

•Microbial mat ichnoassociation. Intertidal microbial mats are characterized by horizontal,gently winding burrows without branching (Helminthoidichnites; tunnel diameter: 1 mm). Thesetraces accurately follow the interface between the organic-rich and the mineral-rich layer ofmicrobial mats (Fig. 1B). The observed Helminthoidichnites reflect the mining of the microbial matfrom underneath: ‘undermat mining behaviour’ sensu Seilacher (1999). Similar behaviouralstrategies were particularly common within Proterozoic microbial mats, before of the AgronomicRevolution (Seilacher, 1999). Obviously, the Helminthoidichnites from Grado correspond toProterozoic-style behaviour but the tracemakers are modern: insect larvae (undeterminedDiptera). Intertidal insects (Heterocerus flexuosus) are also the authors of Macanopsis, anunbranched burrow with a lower clavate chamber and a convolute, tapered neck (maximumpenetration depth: 5 cm; Fig. 1C).

•Rippled sands ichnoassociation. Rippled sands are dominated by deep (20-30 cm)U-shaped burrows (Arenicolites) produced by sipunculans (Fig. 1D). Vertical burrows withconstructional lining (Skolithos) are common especially on longshore bars; thesuspension-feeding polychaete Megalomma is the tracemaker. With the exception of localizedclusters with dense Thalassinoides, crustacean burrows are very rare. These elements closelyresemble pre-Jurassic ichnoassociations, when decapod crustaceans were not dominatingshallow marine environments.

The mentioned ancestral features are explained by the peculiar intertidal environment of theGrado lagoon. Indeed, the studied microbial mats are characterized by extreme conditions: highcohesiveness, prolonged emersion time and noxious phosphate content. For these reasons, theyrepresent a rich trophic niche available only to few non-marine specialists. On the other hand,rippled sands provide less extreme conditions, i.e. relatively high turbulence and low nutrients.However, decapod crustaceans prefer to settle within the adjacent sheltered, organic-richhabitats.

The described ichnologic features, united to the peculiar physiographic and ecologicalcontext, make Grado an ideal analogue for past peritidal ichnological systems. ParaphrasingMcKinney (2007), the Grado ichnosite allows to study “deep time on a tidal flat”.

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(A) Geographical setting and facies map. (B) Helminthoidichnites (He) and Macanopsis (Ma) are visibleafter peeling off the superficial, organic-rich level of the microbial mats. (C) Microbial mat with Macanopsis.The tracemaker (the coleopteran Heterocerus flexuosus) is arrowed; profile view. (D) Arenicolites (dashed)

with its tracemaker, a sipunculan worm.

Baucon, A. 2008. Neoichnology of a microbial mat in a temperate, siliciclastic environment. In: Avanzini M.,Petti F. Italian Ichnology, Studi Trent. Sci. Nat. Acta Geol., 83: 183-203.Gerdes, G., 2003. Biofilms and macroorganisms, in: Krumbein, W.E., Paterson, D.M., Zavarzin, G.A.(Eds.), Fossil and Recent Biofilms: a Natural History of Life on Earth. Kluwer Academic Publishers,Dordrecht, pp. 197-216.McKinney, F.K., 2003. Preservation Potential and Paleoecological Significance of Epibenthic SuspensionFeeder-Dominated Benthic Communities (Northern Adriatic Sea ). Palaios 18, 47-62.McKinney, F.K., 2007. The Northern Adriatic Ecosystem: Deep Time in a Shallow Sea. Columbia UniversityPress, New York.McKinney, F.K., Hageman, S.J., 2006. Paleozoic to modern marine ecological shift displayed in thenorthern Adriatic Sea. Geology 34, 881-884.Seilacher, A., 1999. Biomat-related lifestyles in the Precambrian. Palaios 14, 86-93.Zuschin, M., Stachowitsch, M., 2009. Epifauna-Dominated Benthic Shelf Assemblages: Lessons From theModern Adriatic Sea. Palaios 24, 211-221.

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A QUANTITATIVE TOOL FOR THE ICHNOLOGICAL ANALYSIS OF TIDALENVIRONMENTS: THE ICHNOGIS METHOD

Andrea BAUCON, Fabrizio FELLETTI

DIPARTIMENTO DI SCIENZE DELLA TERRA, Università di Milano, 20133, Milano, Italy,[email protected]

Since its earliest roots in Renaissance times, trace fossil analysis relied on actualisticexperiences for inspiring and testing theories and models. In fact, each of the major watershedsin the history of ichnology was initiated by advances in neoichnological knowledge: thepaleoichnological knowledge of Leonardo da Vinci was inspired by modern burrowing and boringorganisms (Baucon, 2010), the experiments of Nathorst disproved the botanical interpretation oftrace fossils, the Senckenberg Laboratory marked the development of the modern approach inichnology (Osgood, 1975). With the Internet and GPS among the faster-growing technologies ofthe decade, the previous historical considerations addresses traditional questions with novelapproaches: How are traces distributed on a tidal flat? What are the association patterns (‘links’)between ichnotaxa? What is the relationship between traces and their tidal environment?

With these questions in mind, we present a new method to capture, manage, analyze, anddisplay geographically referenced ichnological data: IchnoGIS. This new method uses spatiallocation as the key index variable for all other information, recorded during different samplingstages (Fig. 1A):

a) quadrat sampling. For each sampling site, a frame (quadrat) of a set size is placed on thesubstrate. Spatial coordinates, facies and ichnological attributes (i.e. abundance of eachichnotaxon) are recorded.

b) trench sampling. Quadrat sampling emphasizes the recognition of distinct structures onthe sediment surface, being unsuitable for burrows with poorly visible openings. Consequently,quadrat sampling is complemented by the study of vertical trenches, realized at regularly spacedsites.

c) environmental and topographical sampling. Several environmental attributes can berecorded to determine the major control factors on trace distribution: PH, Reduction Potential(Eh), nutrients (nitrite, nitrate, phosphate), salinity, depth of the Redox Potential DiscontinuityLayer, emersion time and substrate firmness, measured with the modified Brinell method (Gingrasand Pemberton, 2000).

Data analysis is based on the integration of network theory (Fig. 1B) with geostatisticaltechniques (Fig. 1C). More specifically, geostatistical analysis enables to measure the spatialstructure of burrow distribution and allows to interpolate trace abundance in unsampled positions.Consequently, the IchnoGIS method leads to the definition of ichnological maps in which tracedensity is confronted to geomorphological gradients (Fig. 1C).

Furthermore, network analysis exploits the fact that traces assemble in a complex web-likestructure. Accordingly, an ichnological system can be conveniently described by network graph,which represents ichnotaxa and their connections (Fig. 1B). According to this approach,researchers can analyze not only the degree of association between different ichnotaxa, but alsodescribe how an ichnotaxon is embedded in the whole system. Ichnoassociations can be foundby applying specific pattern-finding algorithms. Finally, the integration of geostatistics and networktheory allows to define the environmental significance of ichnoassociations and find out thefactors controlling an ichnological system.

In order to test the accuracy of the IchnoGIS method, we applied it on a modern tidal flat:the Grado lagoon (Northern Adriatic Sea, Italy). Our results show that the IchnoGIS methodprovides unprecedented research opportunities for ichnologists and sedimentologists, as it allowsto determine accurately spatial distribution, association patterns and environmental significance oftraces from the Grado lagoon. In particular, emersion time, hydrodynamism, substrate firmnessand microbial binding are the major control factors determining the structure and distribution oftrace associations. These structuring factors are used to define a predictive model ofichnoassociation composition, providing an immediate tool for paleoenvironmental reconstitution(Fig. 1D).

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(A) The IchnoGIS method. (B) The IchnoGIS method describes an ichnosite through a network graph(ichnonetwork). The ichnonetwork graph displays which ichnotaxon is associated to which other and

records the intensity of each relation (weight of the connections). Data from the Grado lagoon (Adriatic Sea,Italy). (C) The IchnoGIS method allows to compare environmental data with ichnological maps. In

particular, the figured example considers exposure (or emersion) time. Data from the Grado lagoon(Adriatic Sea, Italy). (D) The Grado ichnological model, as defined by the IchnoGIS method. Cr – Crab

burrows ichnoassociation: dominated by crab burrows, sparse Arenicolites; Th - Thalassinoidesichnoassociation: dominated by Thalassinoides and small Arenicolites; Ar –Arenicolites ichnoassociation:

dominated by large Arenicolites, occasional Skolithos and Thalassinoides; Sk – Skolithos ichnoassociation:dominated by large Skolithos, often lined; Ma – Macanopsis ichnoassociation: dominated by Macanopsis

and Helminthoidichnites; Pa – Parmaichnus ichnoassociation: dominated by Parmaichnus

Baucon, A., 2010. Leonardo Da Vinci, the Founding Father of Ichnology. Palaios 25, 361-367.Gingras, M.K., Pemberton, S.G., 2000. A field method for determining the firmness of colonized sedimentsubstrates. Journal of Sedimentary Research 70, 1341-1344.Osgood, R.G., 1975. The history of invertebrate ichnology, in: Frey, R.W. (Ed.), The Study of Trace Fossils.Springer Verlag, New York, pp. 3-12.

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TIDAL BORE INDUCED SEDIMENTS IN INCISED VALLEYS, UTRILLAS FM, ALBIAN,SW IBERIAN RANGES, SPAIN

M. CHAMIZO BORREGUERO*, N. MELENDEZ*, Poppe DE BOER**

*GRUPO DE ANALISIS DE CUENCAS. DPTO. DE ESTRATIGRAFIA-INSTITUTO DE GEOCIENCIAS(UCM-CSIC), Universidad Complutense, Ciudad Universitaria, 28040, Madrid, Spain,[email protected], [email protected]**SEDIMENTOLOGY GROUP, DEPARTMENT OF EARTH SCIENCES, UTRECHT UNIVERSITY,Budapestlaan 4, 3584 CD, Utrecht, The netherlands, [email protected]

Exceptionally well preserved tidal-bore deposits within Albian siliciclastics in thesouthwestern Iberian Basin, adjacent to the Tethys, are interbedded with sediments formed byephemeral alluvial discharge, tidal reworking and aeolian processes.

The study area is located in the southwestern domain of the Iberian Ranges (EasternSpain) in the Serranía de Cuenca. The Iberian Ranges form a NW-SE striking intraplate fold beltand represent an uplifted (inverted) Mesozoic basin that was formed by crustal thinning duringearlier rift stages. Moreover, the Serranía de Cuenca sub-basin was controlled by minorSSW-NNE extension faults that acted as thresholds during the middle Cretaceous sea-level rise(Meléndez, 1983; Capote et al., 2002). Above Lower Cretaceous synrift continental deposits, thesiliciclastic Albian to Early Cenomanian Utrillas Sandstone Formation is laterally very extensiveand crops out all over the Iberian Ranges.

In five detailed sections recorded near the village of Uña, 14 sedimentary facies weredistinguished and grouped into 5 facies associations: ephemeral alluvial, overbank, tidal flat,aeolian and tidal bore deposits. Ephemeral alluvial discharge and tidal reworking alternated withvarying supremacy, and the continuous presence of ventifacts, feldspars as well as finewindblown sand reflects continued aeolian activity.

Two main units are divided by a laterally continuous, deep and sharp incision attributed to arelative sea-level fall. The Lower Unit, deposited in the (fluvial) alluvial–tidal transition zone,records the evolution from a tidally reworked arid ephemeral alluvial system to tidal flats andaeolian dunes as the result of a progressive decrease of alluvial discharge resulting in anincrease of the tidal and aeolian signature.

The Upper Unit, covering the sharp and deep incision, shows a reactivation of alluvialdischarge, although weaker than in the Lower Unit. The most remarkable characteristics of theUpper Unit are (i) two deep incision surfaces, one at the base of the Upper Unit and a second onehigher in the succession, and (ii) the exceptional and conspicuous presence of high-energyflood-tide-induced deposits, brought in through the deep and likely dry incisions. Two suchdeposits, directly upon the incision surfaces, are interpreted as the product of tidal bores. The twodeep incisions in the Upper Unit, at the base of the two tidal bore deposits, lack ephemeralalluvial deposits suggesting the absence or bypass of alluvial discharge. Thus, erosion andsubsequent fill of these deep incisions are suggestive of two different, successive processes, i.e.(i) erosion, later followed by (ii) deposition, as is characteristic for incised valley fills (Boyd et al.,2006).

The successions ascribed to tidal bore activity are characterised by up to 9 m thick wellsorted sands with carbonate cement and dinoflagellates. Main sedimentary structures arehigh-energy low-angle planar lamination and decimetre-scale gently tangential planarcross-bedding with occasional weak internal erosion surfaces. The palaeocurrent pattern ispersistently inland.

Tidal bore deposits in the Uña outcrop consist of marine sediments carried landinward byhigh-energy flood tides, where alluvial discharge is low or absent, as is the case nowadays fortidal bores (Lynch, 1982; Bartsch-Winkler and Lynch, 1988; Kjerfve and Ferreira, 1993; Chanson,2011). Examples from the fossil sedimentary record are rare. Martinius and Gowland (2011)reported on tidal bore deposits in the Late Jurassic Lourinhã Fm (Western Portugal).

In the case presented here, the sub-basin formed a funnel-shaped estuary connected tothe Tethys. In this way, the tide in the open marine domain may have been amplified by basinresonance, while the funnel-shaped estuary led to a further amplification of the flood tide resulting

15


in landward-directed sediment transport and the formation of the up to 9 m thick successions oflow-angle lamination and gently tangential planar cross-bedding.

Detailed sketch of second incision and tidal bore deposits in Uña outcrop (Iberian Basin, Spain).

Bartsch-Winkler, S. and Lynch, D.K. (1988) Catalogue of worldwide tidal bore occurrences andcharacteristics. U.S. Geol. Surv. Circ., 1022, 17.Capote, R., Muñoz, J.A., Simón, J.L., Liesa, L.C. and Arlegui, L.E. (2002) Alpine Tectonics I: The alpinesystem north of the Betic Cordillera. In: The Geology of Spain (Ed: W. Gibbson, T. Moreno). The GeologicalSociety of London. 367-400.Chanson, H. (2011) Current knowledge in tidal bores and their environmental, ecological and culturalimpacts. Environ. Fluid Mech., 11, 77–98.Kjerfve, B. and Ferreira, H.O. (1993) Tidal bores: first ever measurements. Cienc. Cult., 45, 135–138.Lynch, D.K. (1982) Tidal bores. Sci. Am., 247, 134–143.Martinius, A.W. and Gowland, S. (2011) Tide-influenced fluvial bedforms and tidal bore deposits (LateJurassic Lourinhã Formation, Lusitanian Basin, Western Portugal) Sedimentology, 58, 285-324.Meléndez, M.N. (1983) El Cretácico de la Región de Cañete - Rincón de Ademuz (Provincias de Cuenca yValencia) [Tesis Doctoral]. Seminarios de Estratigrafía, Serie Monografías 9. UCM.

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LATE QUATERNARY STRATIGRAPHIC EVOLUTION OF BAEKSU OPEN-COASTTIDAL FLAT, WEST COAST OF KOREA: REGIONAL UNCONFORMITY-BOUNDED

TWO TIDAL DEPOSITS

Taesoo CHANG, Jincheol KIM, Dong-Geun YOO

KOREA INSTITUTE OF GEOSCIENCE & MINERAL RESOURCES, #124, Gwahang-No, Yuseong-Gu,305-350, Daejeon, Korea, [email protected]

Along the eastern margin of the Yellow Sea, numerous macrotidal flats are extensivelydeveloped. In the last two decades, lithostratigraphic studies of these tidal deposits have beenbased on sedimentological anlayses of vibrocores up to ~6 m long, and hence stratigraphicallythe tidal deposits were restricted mostly to the Holocene in age due mainly to lack of deep cores.Another reason for that was likely a general dearth of dateable materials and credibility of agedates prior to the Holocene. One of the important findings from the Korean tidalite researches inthe past was the presence of the semi-consolidated, yellow oxidized layers overlain by Holocenetidal deposits with a stark erosion boundary defining them. Under the situation without any reliableage constraints for that layers, the pre-Holocene strata have been controversial.

In a recent year, however, advanced dating technologies, i.e., OSL and 14C AMS, haveenabled to ensure the age constraints of older tidal deposits dating back to late Pleistocene, andto understand the stratigraphic packages in response to local changes in sea level. Previousworks showed that some tidal deposits at the Korean west sea coasts can be grouped into atleast two unconformity-bounded sequences, which formed in response to late Quaternarysea-level fluctuations (Lim and Park, 2003; Choi and Dalrymple, 2004; Choi and Kim, 2006).However, some age dates determined by AMS, particularly ages around 40,000~50,000 yr BP,are still questionable, the ages leading to discrepancy between the curve reconstructed and theelevation of the deposits. In order to elucidate the chronostratigraphic problems, an OSL datingmethod was applied to the pre-Holocene tidal deposits recovered from the Baeksu tidal flat,Korea. In addition, the relationship between the seismic reflection boundary and the lithologicsurface based on the analysis of seismic profiles and deep- drilled cores will be addressed.

Sediment cores from an open-coast, Baeksu macrotidal flat, Korea, contain about 45 mthick two tidal deposits stratigraphically separated by a yellow, semi-consolidated mud layer and agravel layer. Two tidal units, a Holocene unit and an underlying late Pleistocene unit, haverecurred, as previously reported in the other tidal basin. In the course of core examination, theBaeksu open-coast tidal deposits can be grouped into distinct 6 facies associations, shorefacesands, sand flat, gravelly channel lags, paleosoil horizons, mudflat/salt marshes, and fluvialgravel lags with muds in descending order. The Baeksu tidal flats comprise at least twosequences which formed in response to fluctuations in local sea-level during the late Quaternary.The oxidized layer characterized by semi-consolidated, yellowish sediments separates them,producing a regional unconformity. Such an unconformity-bounding surfaces correlate well with aprominent mid-reflector, observed on seismic profiles. Consequently, the layer associated withthe striking reflector may signify the emergence of the Yellow Sea shelf during the pre-Holocenelowstand. Each sequence consists of lower fluvial deposits and overlying tidal deposits. However,intertidal sands are commonly missing in lower sequence. The presence of two tidal depositswarrants that two cycles of major sea-level fluctuations are recorded, the similarity betweenHolocene and late Pleistocene tidal deposits indicating macrotidal regime recurred in the region.The extensive shallow shelf and relatively stable tectonic setting of the Yellow Sea appears topromote the repetition of tidal sedimentation in the Baeksu open-coast tidal flat.

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Columnar sections of drillcores and their stratigraphic evolution. Unit I and II are separated by a sharperosional surface, interpreted here as a sequence boundary which defines between the upper Holocene

and the lower pre-Holocene deposits.

Choi, K.S., Dalrymple, R.W. (2004) Recurring tide-dominated sedimentation in Kyonggi Bay (west coast ofKorea): similarity of tidal deposits in late Pleistocene and Holocene sequences. Marine Geology, 212,81-96.Choi, K.S., Kim, S.-P. (2006) Late Quaternary evolution of macrotidal Kimpo tidal flat, Kyonggi Bay, westcoast of Korea. Marine Geology, 232, 17-34.Lim, D.I., Park, Y.A. (2003) Late Quaternary stratigraphy and evolution of a Korean tidal flat, Haenam Bay,southeastern Yellow Sea, Korea. Marine Geology, 193, 177-194.

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BAEKSU OPEN-COAST TIDAL FLAT OF THE KOREAN WEST SEA COASTREVISITED: A DEPOSITIONAL MODEL AND ITS PRESERVATION POTENTIAL

Taesoo CHANG

KOREA INSTITUTE OF GEOSCIENCE & MINERAL RESOURCES, #124, Gwahang-No, Yuseong-Gu,305-350, Daejeon, Korea, [email protected]

In a recent year, open-coast tidal flats and its ancient analogues have been increasinglyreceived attention, as they are a hybrid depositional system controlled by the interaction of wavesand tides. In a consequence, some attempts were made to distinguish between a classical tidalflat and wave-dominated tidal flat, and between tidal shoreface and open-coast tidal flat too (Yanget al., 2005, 2008; Basilici et al., 2011; Fan, 2012). Baeksu open-coast tidal flats were previouslyreported as such a typical hybrid coastal system, wave-dominated in winter and tide-dominated insummer due to the seasonal wind distribution. However, the arguments for this open-coast tidalflat model were raised and alternative interpretations suggested as two facies models, anintertidal shoreface for outer part and an estuarine tidal flat model for inner part (Chang andFlemming, 2006). In this regard, we revisited on the open-coast tidal flats in order to fulfill thearguments and to discuss a depositional model for hybrid tidal flats with respect to preservationpotential. For this purpose, over 200 surface sediments were taken from intertidal to subtidalregions using a grab-sampler. Vibro-coring was carried out along the two transects placed acrossthe reclaimed area.

The Baeksu tidal flats are 6~10 km wide and ~10 km long and it opens directly to the YellowSea without any barriers and the coast-oblique subtidal sand bars boarder the seaward margin ofthe tidal flats. Near the high-tide line, the artificial dikes were built and the upper flats have beenreclaimed over the century. Beyond the reclaimed area where the villages are located, thedegraded coastal dune fields occur. The only topographic features on the flats are the low-relief,shore-parallel swash bars and tidal channels are restricted to upper mud flats and salt marshes.The tide is semidiurnal with a mean tidal range of 3.9 m, corresponding to the lower macrotidalregime. The wind regime is predominantly influenced by the monsoon, leading to strongseasonality. Significant wave heights vary between <1 m during summer and 2~3 m duringwinter. Suspended matter concentrations measured on the flats were very high, in summerexceeding ~1 g/l.

The grain-size distribution patterns clearly show the transition of facies belts betweenshoreward coarsening along the outer section and shoreward fining along the inner section. Themorphology of the tidal flats is concave-up in the outer section, grading into inner convex-upabove the mean sea level. The tidal-flat sedimentation is strongly influenced by the seasonalvariation, the area switching between muddy tidal flats in summer and storm-dominated, sandyflats in winter. Particular feature is the fluid muds up to ~1 m thick in summer, these beingexpanded onto the upper middle flats. In winter, these are completely eliminated and only a feware selectively preserved in subtidal zones.

On the basis of core analysis, the open-coast tidal deposits generally show the coarsening-to fining-upward intertidal-flat succession. The transgressive coarsening-upward succession inresponse to Holocene sea-level rise is usually underlain by lowermost salt marsh and mudflatdeposits. The progradational intertidal sands are overlain with a sharp contact by a thin mudflatdeposit. The storm-generated beds, HCS and plan laminations, tend to decrease in abundance ina landward direction, whereas intertidal heterolithic deposits are volumetrically dominant in thelandward portion. The relative abundance of storm deposits survived in the core record reflectscontinued progradation due probably to a high sediment supply from the offshore.

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Bathymetry of the study area with location of vibra-core and grab-sampling stations (dots) in the Baeksuopen-coast tidal flats, West Coast of Korea. Water depths are in metres relative to Chart Datum

Basilici, G., De Luca, P.H.V., Oliveirmares, E.P. (2011) A depositional model for a wave-dominatedopen-coast tidal flat, based on analyses of the Cambrian-Ordovician Lagarto and Palmares formations,north-eastern Brazil. Sedimentology, DOI: 10.1111/j.1365-3091.2011.01318.x.Chang, T.S., Flemming, B.W. (2006) Sedimentation on a wave-dominated, open-coast tidal flat,southwestern Korea: summer tidal flat-winter shoreface-discussion. Sedimentology, 53, 687-691.Fan, D. (2012) Open-coast tidal flats. In: Principles of Tidal Sedimentology (eds., R.A. Davis, R.W.Dalrymple), Springer, 187-229. Yang, B.C., Dalrymple, R.W., Chun, S.S. (2005) Sedimentation on a wave-dominated, open-coast tidal flat,southwestern Korea: summer tidal flat-winter shoreface. Sedimentology, 52, 235-252.Yang, B.C., Dalrymple, R.W., Chun, S.S., Johnson, M.E., Lee, H. (2008) Tidally modulated stormsedimentation on open-coast tidal flats, southwestern coast of Korea: distinguishing tidal-flat fromshoreface storm deposits. In: Recent Advances in Models of Siliciclastic Shallow-Marine Stratigraphy (eds.,G.J. Hampson, R.J., Steel, P.M., Burgess, R.W. Dalrymple), SEPM Spec. Publ., 90, 161-176.

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TIDAL AND CLIMATE CONTROLS ON THE MORPHOLOGICAL EVOLUTIONS ANDTHE INTERNAL ARCHITECTURE OF A TIDAL BAR: THE PLASSAC TIDAL BAR IN

THE BAY-HEAD DELTA OF THE GIRONDE ESTUARY

Eric CHAUMILLON*, Hugues FENIES**, Julie BILLY***, Jean-François BREILH*

*UMR CNRS 7266 LIENSS, 2 rue Olympe de Gouges, 17000, La Rochelle, France,[email protected], [email protected]**CV ASSOCIES ENGINEERING, 7 Chemin de la Marouette, 64100, Bordeaux, France,[email protected]***CEFREM, UMR 5110, 52 Avenue Paul Alduy, 66860, Perpignan, France, [email protected]

Estuarine tidal bars occur in the mouth and in the bay-head deltas of tide-dominatedestuaries or mixed tide-and-wave dominated estuaries. Tidal bars deposited in estuary mouthsare composed of relatively clean sands whereas tidal bars deposited in bay-head deltas cancontain large quantities of mud. Estuarine tidal bars have an elongated or a lobate morphology,but relatively few studies have been conducted on the lobate category. This study is focused on alobate tidal bar, the Plassac tidal bar, located in the bay-head delta of the Gironde Estuary.

This work is based on: (1) successive bathymetric data (1905-2010) which allow to observethe geomorphological evolution of the bar (century scale), (2) detailed imaging of the bedformsthat cover the surface of the bar (over a few days in 2010, Figure 1) which allow to analyze thesediment dynamic. Those well-constrained evolutions and governing processes, combined withvery high resolution seismic and core data are then used to understand the internal architectureof the tidal bar and the fluvial sediment influx within the bay-head delta at a time scale of acentury.

The sediment transport pattern, inferred from the lee face orientations of subaqueous dunesobserved on very high resolution bathymetric data acquired in 2010 (Figure 1), together withresults from previous studies, allows explaining the five main mechanisms for the tidal barevolution identified from 29 bathymetric maps since 1905: flood ramp infill, partial ebb shieldbreaching, lateral accretion of the ebb spits and ebb shield lengthening, generated by the mergingof mini-flood lobes on the outer sides of the ebb spits. Lateral accretion seems to be akey-process of sediment accretion for lobate tidal sand bars. Most of the evolutions are explainedby tidal processes, but fluvial influence is evidenced by correlating the presence of mini floodlobes (migrating seaward from the upper reaches of the bay-head delta) and the lengthening ofthe tidal bar with periods of high fluvial discharge. A 25 years periodicity in both the fluvialdischarge and the tidal bar width, length and volume variations is evidenced and suggest theclimate control on the tidal bar evolution.

Seismic and core data show that the bar was deposited onto a basal bounding surfacewhich consist of a discontinuous sub horizontal reflector correlated with sand and clayalternations and which may represent the main flooding surface within the Gironde Estuary.Within the sandbar, the master bedding corresponds to strong amplitude reflectors (clinoforms)correlated with continuous inclined mud-rich strata. Correlation with bathymetric data shows thatclinoform orientations are not indicative of tide-induced sand transport direction but record theprogressive lateral accretion of the sandbar generated by fluvial sand influx. Thus it appears thatthe internal architecture of the bar is dominated by lateral accretion of sand packages, isolatedfrom one another by extensive inclined mud layers. A major strong amplitude inclined reflector,observed in the eastern ebb spit of the sandbar, is correlated with a 20 cm thick bed made ofangular mud pebbles and was deposited between 1991 and 1993. Considering the period of timebetween 1958 and 2008, the years 1991 to 1993 were characterized by the largest number ofautumn river floods and preceded by the years 1989 to 1991, characterized by the largest numberof days of low river stage. A 3-step depositional process is proposed to explain the heterogeneitypresent within the internal architecture of the tidal bar: (1) during periods of low river stage, theturbidity maximum of the Gironde Estuary is located upstream, in the bay head delta, leading tomud deposition on the sandbars; (2) subsequent periods of floods (especially autumn floodsoccurring immediately after the dry summer season), lead to erosion of the mud drape lying onthe sandbar and to deposition of a mud clasts layer rapidly buried by massive sand transport.

From this study it appears that sandbars emplaced in bay head deltas of estuaries areheterolithic bodies dominated by tides and influenced by fluvial processes. The fluvial influenceimplies that they have a good potential to record high frequency climate changes. During periodsof low rainfall and low river stage, sand supply to the tidal bar is reduced and mud depositionoccurs on the tidal bar, whereas during high rainfall and associated floods, seaward sandtransport increases and leads to tidal bar lengthening, lateral accretion processes and rapidburying of antecedent morphological features and strata.

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High resolution digital elevation model (1.3 m grid) of the Plassac Tidal Bar Plassac Tidal Bar in 2010(From Billy J., Chaumillon E., Féniès H. and Poirier C., Geomorphology, in press).

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TIDAL RHYTHMITES IN THE UPPER CRETACEOUS NESLEN FORMATION, UTAH,USA: THEIR IMPLICATIONS FOR THE SEDIMENTOLOGY AND STRATIGRAPHIC

ARCHITECTURE OF TIDAL-FLUVIAL CHANNEL

Kyungsik CHOI*, Ronald STEEL**, Cornel OLARIU**

*FACULTY OF EARTH SYSTEMS AND ENVIRONMENTAL SCIENCES, CHONNAM NATIONALUNIVERSITY, 300 Yongbong-Dong, Buk-Gu, 500-757, Gwangju, Korea, [email protected]**JACKSON SCHOOL OF GEOSCIENCE, UNIVERSITY OF TEXAS AT AUSTIN, 1 University StationC9000, 78712, Austin, Usa

Upper Cretaceous Neslen Formation in the Floy Canyon, Utah is dominated by multiplestackings of tidal-fluvial channel deposits that consist of inclined heterolithic stratification (IHS)(Figure top). Each channelized unit is 3 – 10 m thick and has an upwardly fining succession witha sharp and erosional base and a gradational top of coaly mud. IHS has variable dips rangingfrom 2 and 5 degree and consists of rippled fine to medium sandstone and interlaminatedsiltstone to mudstone. On the basis of facies association and stratigraphic occurrence, four typesof tidal rhythmites (TR) are identified within the IHS (Figure down). TR is composed of mostlysiltstone and less commonly very fine sandstone, exhibiting neap-spring tidal cycles and diurnalinequalities. TR is either planar laminated or rippled. Ripples are commonly unidirectional andmigrating updip of IHS. Type 1 TR is composed of rhythmically laminated very fine to siltstonethat alternates with non-cyclic rippled sandstone, occurring near the base of channel. Rippledsandstone has a highly variable thickness and geometry with an erosional base. Type 2 TRconsists of alternating rippled sandstone and laminated mudstone, wherein the former representsspring tides and the latter neap tides. Type 2 TR is common in the lower to upper part of IHS unit.Type 3 TR is defined by rhythmically climbing ripple lamination, exhibiting rhythmic changes incross-laminae thicknesses. Type 3 TR is mainly present at the top of IHS unit. Type 4 TR is madeup of laminated siltstone that is either planar or inclined, occurring in the middle to upper part ofIHS. The prevalence of updip migrating ripples on the IHS suggests that rhythmic tidal depositionoccurred in a highly sinuous and actively migrating channel, where mutually evasive tidal currentis well established. Type 1 and Type 2 TR represent subtidal point bar deposition while Type 3and Type 4 TR reflect intertidal point bar deposition.

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Top: Outcrop photograph (A) and linedrawings (B) showing multiple stacking of IHS (inclined heterolithicstratification) units of 2-5 m thick, which is developed in the Upper Cretaceous (Campanian) Neslen

Formation, Horse Canyon area, Utah, USA. Down: Tidal rhythmites (TR) from Neslen Formation. (A) Type1 TR showing gradual change of laminae thicknesses reflecting neap-spring tidal cycle, which is found in

the interbbeded rippled sandstone and rhythmically laminated sandstone. (B) Type 2 TR consists of rippledsandstone beds that exhibit well-defined cyclicity in ripple heights that varies sinusoidally. (C) Rhythmicallyclimbing rippled sandstone illustrating a gradual change in ripple height and wavelength (Type 3 TR). (D)Thinly and faintly laminated sandstone with rhythmic lamination thickness variation (Type 4 TR). White

arrows indicate neap-stage laminae.

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RAPID INFILLING OF MACROTIDAL ESTUARY DURING EARLY HOLOCENE INYEOCHARI TIDAL FLAT, GYEONGGI BAY, WEST COAST OF KOREA

Kyungsik CHOI, Jae Hoon JUNG, Joo Hee JO

FACULTY OF EARTH SYSTEMS AND ENVIRONMENTAL SCIENCES, CHONNAM NATIONALUNIVERSITY, 300 Yongbong-Dong, Buk-Gu, 500-757, Gwangju, Korea, [email protected]

Recent drilling campaign unveiled up to 12 m thick tidal rhythmites (TR) in the lower part ofHolocene successions at Yeochari tidal flat, west coast of Korea (Figure top). Various tidalrhythms are encoded in the TR, which include diurnal inequality, synodic neap-spring cycle,fortnightly inequality, and semi-annual cycle (Figure down). Reduced number of laminae in aneap-spring tidal cycle, accentuated anomalistic cycle, fine-grained nature and close associationwith organic-rich muds are all suggestive of upper intertidal origin of the TR. Abnormally thickneap-spring tidal cycles are interpreted to be associated with monsoon discharge period.Recurrence of TR bounded by organic-rich muds indicates that base-level has been fluctuatedduring the deposition of the TR. Sedimentation rate inferred from the TR ranges from 1.7cm/month to 10 cm/month with the maximum annual rate reaching up to 0.3 m. Stratigraphicanalysis with AMS dating indicates that TR-deposition occurred in the topographic lows betweenmain channels during early Holocene (10~8 ka) when sea-level rose at the maximum rate of 2 cmper year. Given the stable tectonic condition of study area, the generation of accommodationspace due to the rapid base-level rise combined with antecedent topography that effectivelyfacilitated protection from storms seems to have played a key role in the creation andpreservation of unusually thick and delicate tidal records during Holocene transgression.

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Graphic summary of columnar section of BH 16. Tidal rhythmites demonstrate various tidal cyclicitiesincluding diurnal inequality, synodic neap-spring cycle, anomalistic neap-spring cycle, and presumably

semi-annual cycle. White arrows indicate neap-tides laminae. Note well-developed rhythmites are mainlypresent in the early Holocene unit (8 ka~9 ka), which was formed during rapid transgression. Depths are

meters below present mean sea level.

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MORPHODYNAMICS OF TIDAL CHANNELS IN THE MACROTIDAL YEOCHARITIDAL FLAT, GYEONGGI BAY, WEST COAST OF KOREA: IMPLICATION FOR THE

ARCHITECTURE OF INCLINED HETEROLITHIC STRATIFICATION

Kyungsik CHOI, Chang Min HONG, Chung Rok OH, Jae Hoon JUNG

FACULTY OF EARTH SYSTEMS AND ENVIRONMENTAL SCIENCES, CHONNAM NATIONALUNIVERSITY, 300 Yongbong-Dong, Buk-Gu, 500-757, Gwangju, Korea, [email protected]

Morphodynamics of intertidal channels were monitored using a total station and RTK GPSin the Yeochari tidal flat, Gyeonggi Bay, Korea. Along the transect YC-1, four channels (CH-1,CH-2, CH-3, and CH-4 from seaward to landward) are present in the lower intertidal flat (Figure1). They are 240-570 m wide and 1.2-2.4 m deep at bankful stage. Three-year-long observationsreveal that channels migrate at a noticeable rate with strong seasonality. In particular, CH-4migrated about 200 m in 30 months. During summertime in 2010 and 2011, it migrated as muchas 40 m in a month, respectively, which leads to rapid accumulation up to 40 cm in the point barposition of channel. In contrast, migration rate decreased down to 5 m per month between fall tospring. Difference in channel migration between summer and the rest of year can be explained bythe occurrence of enhanced ebb currents due to increased runoff discharge during summertime.Point-bar geometry alternates between a concave-up profile in summertime and convex-up profilein the rest of season (Figure 3). Varying degree of rill erosion in the upper point bar results in theseasonal morphologic change. Pronounced rill erosion and high suspended sedimentconcentration in summertime led to rapid accumulation of sediment at channel base, creating aconcave-up point-bar geometry. Continued sedimentation with little rill erosion resulted in aconvex-up point-bar geometry during the rest of season. Present study suggests that the externalarchitecture of inclined heterolithic stratification of intertidal origin is controlled by seasonality inprecipitation.

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Top: Diagram of transect YC-1 showing morphologic features of Yeochari tidal flat. Upper tidal flat has aconcave-up profile. Small channels are present in the concave to convex-up middle tidal flat. Lower tidal flat

is characterized by channels and interchannel areas covered by migrating dunes. Down: Temporalmorphologic variation of channel profiles at CH-4, displaying a distinct seasonality. Point bar attains a

concave-up profile during summertime, whereas it has a convex-up profile during the rest of season. Suchseasonal morphologic change resulted from monsoon-driven runoff discharge.

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WARM-TEMPERATE, MARINE, CARBONATE SEDIMENTATION IN AN EARLYMIOCENE, TIDE-DOMINATED, INCISED VALLEY; PROVENCE, SE FRANCE

Robert W. DALRYMPLE*, Noel JAMES*, Meg SEIBEL*, David BESSON**, Olivier PARIZE***

*DEPT. GEOL. SCI. & GEOL. ENG., Queen'S University, K7L 3N6, Kingston, Ontario, Canada,[email protected], [email protected], [email protected]**SHPEC/DHMD, 5 Avenue Buffon, 4064, Orleans Cédex 2, France, [email protected]***AREVA NC, 1 Place Jean Millier, 92084, Paris la Défense, France, [email protected]

The Miocene in southern France was generally a time of tidal sedimentation. Some of themost spectacular tidal deposits occur in a series of incised valleys that were cut into oldersediments during a succession of sea-level lowstands, and back-filled during sea-level rises bytidal deposits with variable amounts of bioclastic carbonate material. We have examined one ofthese valleys in detail, using a combination physical and carbonate sedimentological approaches,to obtain a more holististic paleoenvironmental reconstruction.

The Saumane-Venasque paleovalley is oriented north-south and cuts across the westerlyend of the Vaucluse Mountains that were rising at the time of valley incision and filling. The valleyis narrow (2-5 km wide) and has several tributaries entering from the east and west. The portionof the valley between Saumane and Venasque is filled with well-cemented limestones, but themore northerly part of the valley is empty, presumably because it was filled with less permeable,finer-grained material that was not as tightly cemented. Paleogeographic reconstructions indicatethat the estuary contained one, gently sinuous, main channel that was up to 25 m deep andflanked by shoals that were cut by smaller channels tied to the tributary valleys. The generalmorphology of the system was broadly similar to that the modern-day Scheldt estuaries in TheNetherlands. However, the preserved valley-filling deposits may represent a flood-tidal delta (thesystem was overwhelmingly flood dominated as indicated by the pervasive presence ofnorthward-direct cross bedding) that passed landward into a muddy “lagoon” that existed in theexhumed (empty) valley to the north.

The water in this “estuary” was warm-temperate, with normal marine to mildly brackishsalinities. The absence of significant river input during valley filling led to the deposition ofextensive calcarenites that are pervasively cross-bedded. All of the limestones are variably rich inquartz, glauconite, and minor phosphate. The principle biofragments are echinoids, bryozoans,coralline algae, barnacles, and benthic foraminifers. Particles are largely parautochthonous,produced in seagrass meadows on the flanking shoals, on rocky substrates along the valley wallsthat were colonized by macroalgae (kelp), and within the subaqueous dune fields thatcharacterized the channels and their flanks. Some of the grains could have been brought into theestuary from areas farther seaward by the flood-dominant currents.

The valley fill is compound, and is partitioned into two sequences and three subsequences(Fig. 1; Besson, 2005; Seibel, 2009). Many packages have a similar upward progression ofdeposits, the complete succession consisting of six stages: 1) a basal erosional surface that islocally bored and glauconitized, which represents the sequence boundary; 2) a discontinuous unitof lagoonal lime mudstone or wackestone; 3) an overlying thin (< 1 m) conglomerate that is thetidal ravinement surface; 4) a decameter-thick TST series of pervasively cross-beddedcalcarenites that formed within the main estuary channel; 5) a several meter–thick maximumflooding interval (MFI) of argillaceous, bioturbated muddy quartzose limestones that accumulatedin an open-marine setting, in water depths of ~ 50 m after the interfluves were inundated; and 6) alocal thin HST of fine-grained calcarenite. Tidal currents during stages 2 and 3 were accentuatedby the constricted topography, but the tidal currents did not decrease immediately after flooding ofthe interfluves, but continued to be strong as water depths increased, forming formset dunes upto 7 m in height on top of the valley fill (sensu strito). These strong tidal currents in deep waterare presumably due to far-field influences associated with the transgressive expansion of theseaway in the Rhodanian foreland basin farther north.

There is a temporal change in the composition of the overall succession with quartz,barnacles, encrusting corallines, and epifaunal echinoids decreasing in abundance upward,whereas bryozoans, articulated corallines, and infaunal echinoids increase in numbers upwardthrough the sequence set. This trend is interpreted to be the result of changing oceanographicconditions as the valley was filled, bathymetric relief was reduced, rocky substrates were replacedas carbonate factories by seagrass meadows and subaqueous dunes, and the setting became

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progressively more open marine. These cool-water limestones are characteristic of a suite ofsimilar calcareous sand bodies, located elsewhere in southern France and beyond, thatdeveloped in environments with little siliciclastic or freshwater input during times of high amplitudesea-level change, wherein complex inboard antecedent topography was flooded by a risingocean.

((Upper) Simplified vertical succession of deposits within the Saumane-Venasque incised-valley fill. (Lower) Simplified cross section of the Saumane-Venasque incised-valley fill. (Modified after Besson,

2005).

Besson, D., 2005, Architecture du bassin Rhodano-Provençal Miocéne (Alpes, S.E. 1220 France): relationsentre déformation, physiographie et sédimentation dans un 1221 basin molassique d’avant-pays. EcoleNationale Supérieure des Mines de Paris, 1222 Paris, 250 pp.Seibel, M.J., 2009, Deposition and diagenesis of the Miocene Saumane-Veasque limestones, southeasternFrance. Unpubl. M.Sc. thesis, Queen's University, Kingston, ON, 144 p.

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LIVE UNDER TIDAL REGIME: THE ROLE OF THE BRITTLE-STAR OPHIOTHRIXFRAGILIS BEDS FROM THE EASTERN BAY OF SEINE IN THE FINE PARTICLE

DEPOSIT-SUSPENSION MECHANISMS

Jean-Claude DAUVIN*, Khadija BERYOUNI**, Sophie LOZACH*, Yann MEAR**, Anne MURAT**,Emmanuel POIZOT**

*UMR CNRS 6143 M2C, UNIVERSITE DE CAEN, 24 rue des Tilleuls, 14000, Caen, France,[email protected]**GEOCEANO, Cnam/intechmer bp 324, 50110, Tourlaville, France

In the English Channel, the brittle-star Ophiothrix fragilis is a common epifauna speciesmainly found in strong tidal current characterized by pebbles benthic habitats (Holme, 1984). Inthe Bay of Seine, O. fragilis is however living on gravel and coarse sandy sediments and morelocally, it occurs in areas with unexpected amount of fine particles for such high hydrodynamicareas (Mear et al., 2006; Lozach et al., 2011). This species forms dense aggregation supportinghigh density populations (1,500 to 7,000 ind.m-2) and both ophiuroid aggregation morphology andbehaviour of juveniles play an important role in formation of relatively large patches in term ofsurface area on the seafloor. Moreover, living in dense aggregations may reduce displacement bystrong currents (Warner and Woodley, 1975). Adults, although mobile, are not highly active, butO. fragilis can be a crawling epibenthic species; individuals will crawl back and forth across watercurrents until a conspecific was found (Broom, 1975). Some migration of adults from nearbypopulations may be possible. Where dense Ophiothrix aggregations are found on bedrocksurfaces they may monopolize the substratum, virtually to the exclusion of other epifauna. Incontrasts, beds on soft bottom may contain a rich associated fauna, with a dominance of largesuspension-feeders. In addition, O. fragilis plays a major role in pelago-benthic transfer ofparticles from the water column to the benthic habitats due to its suspension feeding activity(Davoult and Gounin, 1995).

At the scale of the Bay of Seine patches Gentil and Cabioch (1997) suggest that O. fragilisshow spatial changes along the years due the variability of the recruitment; but, in the DoverStrait, some had remained stable in the long term (Davoult and Gounin, 1995). By contrasts, inthe Plymouth area, dense Ophiothrix beds showed large long-term fluctuations from the end ofthe 19th century, to the 1970’s (Holme, 1984). Later, for the Bay of Seine, Lozach et al. (2011)have showed that the patches of abundances presented several spatial scales of organisation,from small scales (differences between grab replicates), local scales (differences between sites)and regional scales (differences between areas in the Bay of Seine).

The accumulation of benthic data during the last 25 years in the eastern part of the Bay ofSeine from several scientific programmes permits to revisit the spatio-temporal structure patternsof the Ophiothrix fragilis population in this area. The objective of this communication is to analysethe temporal changes of the O. fragilis aggregation from 1986 to 2010 in a tidal area affected bythe Seine estuary and submitted to potential sediment supply from the dumping site of Le Havreharbour dredging operations. During all surveys, there was a similar pattern, i.e. persistence ofstations with high abundances of Ophiothrix and stations with the absence of Ophiothrix showingthat there was a high heterogeneity of the spatial population pattern. Finally, it is possible topropose a conceptual model for the evolution of the Ophiothrix fragilis beds offshore Antiferharbour in an area under the influence of natural and anthropogenic constraints (Figure 1). Inaddition to the fine particles input from the Seine estuary and the Octeville deposit area of LeHavre habour, when a dense population of brittle-star is established on this gravely substrate, thesilting increases due to biological influences.

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Schematic model of evolution of the seabed in the Bay of Seine under the four actions of Seine Riverdischarges, tidal currents, swell and high Ophiothrix fragilis populations

Broom, D.M., 1975. Aggregation behaviour of the brittle-star Ophiothrix fragilis. Journal of the MarineBiological Association of the United Kingdom 55, 191-197.Davoult, D., Gounin, F., 1995. Suspension feeding activity of a dense Ophiothrix fragilis (Abildgaard)population at the water-sediment interface: Time coupling of food availability and feeding behaviour of thespecies. Estuarine Coastal and Shelf Science 41, 567-577.Gentil, F., Cabioch, L., 1997. Les biocénoses subtidales macrobenthiques de la Manche, conditionsécologiques et structure générale. In: Dauvin J.C., (édit.) 1997. Les biocénoses marines et littoralesfrançaises des côtes Atlantique, Manche et Mer du Nord, synthèse, menaces et perspectives. MNHN,Paris, 68-78.Holme, N.A., 1984. Fluctuations of Ophiothrix fragilis in the Western English Channel. Journal of the MarineBiological Association of the United Kingdom 64, 351-378.Lozach, S., Dauvin, J.C., Méar, Y., Murat, A., Dominique Davoult, D., Migné, A., 2011. Sampling Epifauna,a Necessity for a Better Assessment of Benthic Ecosystem Functioning: An Example of the EpibenthicAggregated Species Ophiothrix fragilis from the Bay of Seine. Marine Pollution Bulletin 62, 2753-2760.Méar, Y., Poizot, E., Murat, A., Lesueur, P., Thomas, M., 2006. Fine-grained sediment spatial distributionon the basis of a geostatistical analysis: Example of the eastern Bay of the Seine (France). ContinentalShelf Research 26, 2335-2351.Warner, G.F., Woodley, J., 1975. Suspension-feeding in the brittle star Ophiothrix fragilis. Journal of theMarine Biological Association of the United Kingdom 55, 199-210.

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MILANKOVITCH-SCALE ORBITALLY FORCED TIDAL CYCLICITY

Poppe DE BOER

DEPT OF EARTH SCIENCES, P.o. box 80.021, 33508TA, Utrecht, The netherlands, [email protected]

Milankovitch-scale variations in insolation affect climate and oceanography, and contributeto the generation of cyclic sedimentary successions, especially at critical latitudes. Commonoceanographic principles show that also the ocean tide responds to variations in the orbitalparameters (de Boer and Trabucho-Alexandre, 2012). Variations of the ocean tide, due tochanging eccentricity (at present 0•0165; theoretical maximum 0•0728) and precession affect avariety of oceanographic and related sedimentary processes. Having the same frequency, theireffects may be mixed up with, blurred by, or add to the insolation effects. Gravitation-dependentvariations of the tide are related to the third power of the distance to the Sun. Insolation only hasa quadratic relation. Thus the tidal effects should be felt especially in periods of high eccentricity.

Variations of the ocean tide due to the, much shorter, 18•6 year lunar nodal cycle, whichhas no insolation counterpart by which they may be obscured, produce relatively small, order of5%, variations of tidal amplitude and tidal currents. This leads to significant effects in sedimentaryenvironments that are sensitive to variations in the strength of the tide. For example, progradationand retreat of tropical coastlines (Gratiot et al., 2008), ebb-tidal delta behaviour and erosion andsedimentation on adjacent barrier islands (Oost et al., 1993), the morphodynamics of estuaries(Wang and Townend, 2012), mean-sea-level changes (Peterson, 1988), and Arctic climate andfishery stocks (Yndestad et al., 2008) have been related to the effects of the Lunar Nodal Cycle.

Orbital variations of the tide on Milankovitch time scales are stronger than those due to the18•6 year lunar nodal cycle. They also should affect sedimentary systems. In the Quaternary andother ice-house periods, rapid sea-level changes may blur such effects. In greenhouse periodswhen sea-level changes are slower by 2 to 3 orders of magnitude, the preservation potential ofsedimentary signals of orbitally forced variations of the ocean tide likely is greater. In suchperiods, variations of the ocean tide may affect the behaviour of barrier coastlines, delta lobeswitching, carbonate platform evolution and processes in the open ocean related to circulationintensity. Especially in cases in which the period of autocyclic changes approaches that ofprecession or eccentricity, orbital variations of the tide may tune cyclic changes in tide-influencedsedimentation patterns.

In analogy with the lunar nodal cycle, semi-precession cycles are to be expected not only atlow latitudes, as is the case with insolation, but also at high latitudes.

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de Boer, P.L. and Trabucho-Alexandre, J. (2012) Orbitally forced sedimentary rhythms in the stratigraphicrecord: is there room for tidal forcing? Sedimentology, 59, 379-392.Gratiot, N., Anthony, E.J., Gardel, A., Gaucherel, C., Proisy, C. and Wells, J.T. (2008) Significantcontribution of the 18.6 year tidal cycle to regional coastal changes. Nature Geoscience,doi:10.1038/ngeo127, 1-4.Oost, A.P., Dehaas, H., IJnsen, F., Vandenboogert, J.M. and de Boer, P.L. (1993) The 18.6 Yr Nodal Cycleand Its Impact on Tidal Sedimentation. Sedimentary Geology, 87, 1-11.Peterson, R.G. (1988) Comparisons of sea level and bottom pressure measurements at Drake Passage.Journal of Geophysical Research, 93, 12439-12448.Wang, Z.B. and Townend, I.H. (2012) Influence of the nodal tide on the morphological response ofestuaries. Marine Geology, 291–294, 73-82.Yndestad, H., Turrel, W.R. and Ozhigin, V. (2008) Lunar nodal tide effects on variability of sea level,temperature and salinity in the Faroe-Shetland Channel and the Barents Sea. Deep-Sea Research I, 55,1201-1217.

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TIDAL INFLUENCE IN THE ‘LOWER RED UNIT’ OF THE TREMP FM INSOUTH-CENTRAL PYRENEES (LATE CRETACEOUS-TERTIARY)

Davinia DIEZ-CANSECO*, M. Isabel BENITO*, Margarita DIAZ-MOLINA*, Otto KALIN**

*STRATIGRAPHY DPT.-COMPLUTENSE UNIV. OF MADRID-IGEO (CSIC-UCM), José Antonio Novais 2,28040, Madrid, Spain, [email protected]**PALEONTOLOGY DPT.-COMPLUTENSE UNIV. OF MADRID-IGEO (UCM-CSIC), José Antonio Novais,2, 28040, Madrid, Spain

Interpreting transitional depositional environment is a difficult task when the ocurrence ofsedimentary features associated with continental environments, such as reddish-colouredmudstone with abundant paleosols are profuse, and there is scarcity or lack of sedimentaryfeatures and/or fossil content indicative of marine influence. This study presents an example of atransitional environment recorded in the Late Cretaceous red deposits of the Tremp Fm in thesouth-central Pyrenees, which traditionally have been considered as continental, but displayevidence of tidal influence.

The studied area is located in the south-central Pyrenees, at the eastern part of thenorthern flank of the east–west-trending Tremp syncline, near Suterranya. This syncline exposesLate Cretaceous-Tertiary deposits reflecting deepening to the west, with a transition fromcontinental to shelf and turbidite facies. In this area, Late Cretaceous-Tertiary succession isrepresented by the Arén Fm, composed mainly of sandstone, which is overlain by the Tremp Fmcomposed of predominantly mudstone and subordinate sandstone (Fig. 1 a). These formationscontain various worldwide known dinosaur fossil sites (Fig. 1 b), which are among the youngest inthe world (López-Martínez et al., 2001). The Cretaceous–Tertiary boundary is enclosed within thelower part of Tremp Fm, although its precise location has not been well established yet.

The stratigraphic succession at Suterranya includes the top of the Aren Fm and the lowerportion of the Tremp Fm. The Aren Fm consists of shallow-marine sandstones interpreted asbeach ridge deposits (Diaz-Molina et al., 2007). This is followed by the Tremp Fm, commonlyknown as the “Garumnian facies”. In the sections studied, the Tremp Fm consists of greyishmudstones with abundant pedogenic features (‘Grey Unit’), interpreted as lagoonal or estuarinefacies.These are followed by reddish to yellowish silty mudstones interbedded with channelizedsandstone and conglomerate (‘Lower Red Unit’), that have been interpreted as fluvial and floodplain deposits (Rossell et al., 2001; Riera et al., 2009). These deposits are overlain by lacustrinelimestones, which have been attributed to the Danian (López-Martínez et al., 2006).

Interestingly, several indications of a marine influence have been detected in both the‘Lower Red Unit’ and the lacustrine carbonate facies. For example, despite the abundantpedogenetic features, such as carbonate nodules precipitaction, reddish to yellowish mottling andrhizolites (Fig. 2 a), the reddish-yellowish silty mudstones are intensely burrowed (Fig. 2 a and b)and contain abundant planktonic foraminifers and calcareous nannoplankton, which do not showany sign of having been reworked from older formations (Fig. 2 c, d, e and f). Moreover, thelacustrine limestones overlying reddish-yellowish siliciclastic deposits contain abundant benthonicforaminifers.

Sandstone bodies in the ‘Lower Red Unit’ are made up of coarse- to fine-grained hybridarenites, with interbedded silty mudstones and conglomerates. Their geometry is tabular orconvex upwards and they are interpreted as point bar bodies. Individual point bar bodies mayreach 2 m in thickness and typically display Inclined Hetherolitic stratification (IHS, Fig. 3), incases intensely burrowed and pedogenetically altered, mainly at the top. Point bar bodies of thesame meander loop are separated by discordances or meander loop reactivation surfaces. Theconvex-upward-shaped bodies represent longitudinal sections trough point bars. IHS deposits areinterpreted as products of point bar lateral accretion, formed in meandering channels with tidalinfluence (sensu Thomas et al., 1987).

Both, marine fauna found in the silty mudstones and the presence of HIS in sandstonebodies strongly suggest that the ‘Lower red Unit’ of the Tremp Fm consists of mudflat depositsincised by meandering channels with tidal influence. Moreover, the presence of abundantforaminifers in the overlaying lacustrine limestones corroborates the interpretation of a marineinfluence in the ‘Lower Red Unit’ of the Tremp Fm. This is in line with the tidal flat environmentalsetting for dinosaur nesting proposed by Sanz et al. (1995) and López-Martínez et al. (2000).

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1/ (a) Mudstone with interbedded sandstone of Tremp Fm. (b) Dinosaur bone remain in the Tremp Fm. 2/Reddish-yellowish silty mudstone facies (‘Lower Red Unit’, Tremp Fm). (a) Burrows and reddish to

yellowish mottling. (b) Detail of a single burrow. (c and d) Planktonic foraminifers. (e and f) Calcareousnannoplankton. 3/ Two superimposed point bars bodies (‘Lower Red Unit’, Tremp Fm). Note IHS in the

lower body.

Díaz Molina, M., Kälin, O., Benito, M.I., López-Martínez, N., Vicens, E., 2007. Depositional setting and earlydiagenesis of the dinosaur eggshell-bearing Arén Fm at Bastús, Late Campanian, south-central Pyrenees.Sedimentary geology 199, 205–221.Lopez-Martinez, N., Moratalla, J.J., Sanz, J.L., 2000. Dinosaur nesting on tidal flats. Palaeogeography,Palaeoclimatology, Palaeoecology 160, 153–163.Lopez-Martinez, N., Canudo, J.I., Ardèvol, L., Pereda Suberbiola, X., Orue-Etxebarría, X., Cuenca-Bescós,G., Ruiz Omeñaca, J.I., Murelaga, X., Feist, M., 2001. New dinosaur sites correlated with UpperMaastrichtian pelagic deposits in the Spanish Pyrenees: implications for the dinosaur extinction pattern inEurope. Cretaceous Research 22, 41–61.López-Martínez, N., Arribas, M.E., Robador, A., Vicens, E., Ardèvol, Ll. Los carbonatos danienses (Unidad3) de la Fm Tremp (Pirineos Sur-centrales): Paleogeografía y relación con el límite Cretácico-Terciario.Revista de la Sociedad Geológica de España 19 (3-4).Rosell, J., Linares, R. & Llompart, C., 2001. El “Garumniense prepirenaico”. Rev. Soc. Geol. Esp. 14 (1-2).Sanz, J.L., Moratalla, J.J., Díaz-Molina, M., Lopez-Martinez, N., Kälin, O., Vianey-Liaud,M., 1995. Dinosaurnests at the sea shore. Nature 376, 731–732.Thomas, R.G., Smith, D.G., Wood, J.M., Visser, J., Calverlyrange, E.A., Koster, E.H., 1987, Inclinedheterolithic stratification; terminology, description, interpretation and significance: Sedimentary Geology v.53, p. 123–179.Riera, V., Oms, O., Gaete, R., Galobart, À., 2009. The end-Cretaceous dinosaur succession in Europe: theTremp basin record (Spain). Palaeogeography, Palaeoclimatology, Palaeoecology 283, 160–171.

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DEPOSITIONAL ARCHITECTURE AND ICHNOLOGY OF THE TIDALLY-INFLUENCEDESTUARINE SYSTEM OF THE EOCENE AMEKI GROUP

Ogechi EKWENYE*, Gary NICHOLS*, Sunny NWAJIDE**, Gordian OBI***

*DEPARTMENT OF EARTH SCIENCES, Royal, TW20 0EX, London, United kingdom,[email protected], [email protected]**SITP, Shell Development Company Limited, 320242, Nigeria, [email protected]***DEPARTMENT OF GEOLOGY, Anambra State University, 430261, Anambra, Nigeria,[email protected]

The Eocene siliciclastic sedimentary facies of the Ameki Group in the south-eastern Nigeriarecords sedimentary response to an initial regression, followed by marine incursion(transgression) into the pro-Niger Delta basin. Detailed studies of several well-exposed sectionsof the Eocene Ameki Group (Figure 1) within an outcrop area of over 1,800 km2 show thatdeposition took place in a setting that varied from coastal to shallow marine. Detailedsedimentological and ichnological studies indicate that the overall setting was of a tidallyinfluenced estuarine system. This interpretation is similar to the description of tide-dominatedestuary (Dalrymple, 1992; Kitazawa, 2007), where a complete preservation of transgressivevalley-fill sediments consist of fining upward sequence from fluvial sands and/or gravel tointerbedded sands and muds deposited in the tidal fluvial transition of inner estuary. This isfollowed by upward coarsening fine grained sand flats sediments and cross bedded sandstone ofelongate tidal sand bars.

Six facies associations (FA1 to FA6) are documented in the study area with well preservedsediments interpreted as fluvial channel, tidally influenced fluvial channel, tidal channel, tidal flats,tidal sand bar and tidal/shallow marine embayment deposits. Facies distribution in the AmekiGroup is similar to that of the Cobequid Bay-Salmon River macrotidal estuary, Bay of Fundy(Dalrymple, et. al. 1990), where the tidal channels and tidal sand bars are bordered by tidal flats.Architectural element analysis is applied to determine the basic building blocks of the estuarinesuccession and to show the spatial arrangement and continuity of sandstone bodies. Thearchitectural elements are grouped into channels, non-channels and heterolithic elements.

Two major temporal controls were responsible for the formation of the non-cyclic and cyclicrhythmites and other tidally-influenced depositional structures observed in the study area. Tidaldepositional cycles include semi-diurnal tidal rhythmites are recognised in tidal bundles andmillimetre-centimetre scale heteroliths whereas decimetre-metre scale cyclic successions indicateseasonal depositional cycles. Similar interpretation is observed in the works of Hovikoski et al.,2008, where they discussed the tidal and seasonal controls of the Upper Miocene sediments ofthe Acre sub-basin, Brazil. The tidal deposits are associated with ichnofacies assemblages ofSkolithos, Cruziana, mixed Skolithos-Cruziana, Glossifungites and Teredolites ichnofacies thatshow variation in intensity and diversity across the facies. The depositional architecture of theEocene Ameki Group has been most probably controlled by relative sea-level changes, sedimentsupply, basin accommodation and regional tectonics consequent upon the location of the NigerDelta at the edge of a trailing continental plate.

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Geologic map of the study area showing the outcrop locations in the Ameki Group

Dalrymple, R.W. 1992, Tidal depositional systems in Walker, R. G. and James, N. P., eds., Facies Models:response to sea level change: Geological Association of Canada, p.195-218.Dalrymple, R.W., Knight, R. J., Zaitlin, B. A. and Middleton, G.V., 1990, Dynamics and facies model of amacrotidal sandbar complex, Cobequid Bay-Salmon River estuary (Bay of Fundy): Sedimentology, v. 37. p.577-612.Hovikoski, J., M. Rasanen, and Gingras, M, Ranzi, A, and Melo, J., 2008, Tidal and seasonal controls in theformation of Late Miocene inclined heterolithic stratification deposits, western Amazonian foreland basin:Sedimentology, v. 55, p. 499-530.Kitazawa, T., 2007, Pleistocene macrotidal tide-dominated estuary–delta succession, along the Dong NaiRiver, southern Vietnam: Sedimentary Geology, v. 194, no. 1–2, p. 115-140.

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SEDIMENTATION PROCESSES AND SEDIMENTARY CHARACTERISTICS OF TIDALBORES IN THE QIANTANG ESTUARY, EAST-CENTRAL CHINA

Daidu FAN, Shuai SHANG, Jinbiao TU, Guofu CAI, Yijing WU

STATE KEY LAB OF MARINE GEOLOGY, 605# Ocean Building, 1239 Siping Road, 200092, Shanghai,China, [email protected]

A tidal bore is a unique Earth surface process, characterized by its highly destructiveenergy, predictable periodicities and magnitudes, and the production of characteristicsedimentary features. Tidal bores and associated rapid flood flows are highly turbulent flows ofthe upper-flow regime with a velocity over several meters per second. Reynolds (Re) and Froude(Fr) numbers, respectively, are larger than 104 and 1.0, making them significantly different fromregular tidal flows but analogous to turbidity currents. Until now, understanding of tidal-boredepositional processes and products has been limited because of the difficulty and hazardsinvolved with gauging tidal bores directly. The Qiantang bore is known as the largest breakingbore in the world. Field surveys were carried out in May 2010, along the north bank of theQiantang Estuary to observe the occurrence of peak bores, including regular observations ofcurrent, water level and turbidity at the main channel. Several short cores were sampled on theintertidal flats to study the characteristic sedimentary features of tidal bores.

Hydrodynamic and sedimentological studies show that the processes of sedimentresuspension, transport and deposition are controlled primarily by the tidal bores, and thesubsequent abruptly accelerated and decelerated flood flows, which only account for one tenth ofeach semidiurnal tidal cycle in the estuary. The asymmetry between the flooding and ebbingphases of tides in the Qiantang Estuary is extraordinary. For example, an ebb duration of morethan 10 hours is approximately four times the flood duration of more than 2 hours observed duringthe spring tides at Daquekou. The maximum near-bottom (1 m above the bed) velocities for thisperiod were 0.7 and 2.1 m/s for the ebb and flood flows, respectively, with the latter being threetimes the former. The maximum turbidity variation usually occurs at the same moment as thepassage of the bore-head, and a few minutes ahead of the maximum flooding regime. Thehydraulic observations at Daquekou showed that the suspended concentration jumped sharplyfrom a minimum value in the range of 0–50 NTU to 1300–1800 NTU within one or two minutesbefore and after the bore. During the following stage, vast amounts of suspended sedimentsshould be deposited rapidly because of a sharp deceleration of flood flows. This lasted only 30minutes with a drastic drop of turbidity from ~1800 NTU to ~450 NTU according to our single fieldobservation. After these first two stages, absolute values of flow speeds and their variationmagnitudes were relatively small. A maximum speed of 0.7 m/s occurred at the rapid ebbingstage, but its general competence to resuspend sediments was presumably low and thesuspended sediment concentration was not observed to increase significantly either. Thesuspended sediment concentration fluctuated between 300 NTU and 500 NTU for a long timefollowing the slow flooding stage, and declined toward zero from the late slow ebbing stage to theslack stage. In short, sedimentation in the bore-affected section of the river is mainly controlled bythe tidal bore and closely related processes, including the abrupt rise in water level, and the rapidincrease and decrease in flow velocities during and immediately after the passing of the tidalbore.

Rapid sedimentation occurs at the sharply decelerated flooding stage, producing poorlysorted deposits characterized by massive bedding, graded bedding and basal scour structures.Soft-sediment deformation structures are also developed, including convoluted bedding anddewatering structures. These occur because of the liquefaction of newly deposited beds thatcontain abundant pore water, triggered by the passage of the bore above. The C-M graphicinterpretation demonstrates that the sediments are mainly transported as suspended loads withonly a slight amount of bed load under fierce vortex turbulence in the bore-affected river section.The differences between tidal-bore and regular tidal deposits are evident not only in sedimentarystructures, with the former having characteristic thick massive beddings and the latter commonlydeveloping with tidal beddings (lenticular, wavy and flaser beddings), mud couplets, andspring-neap tidal cycles, but also in the grain size composition. Scattering plots of any twograin-size parameters have the potential to differentiate the three kinds of tidal deposition: TBD(tidal bore deposit), TSD (tidal sandy deposits) and TMD (tidal muddy deposit), with some generaltrends in terms of mean grain size with TBD>TSD>TMD, sorting of TMD>TBD>TSD (larger valueindicating poorer sorting), and both skewness and kurtosis with TSD>TBD>TMD.

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Acknowledgement: This work was jointly supported by National Natural Science Foundationof China (40876021, 41076016), State Key Lab of Marine Geology (MG200907), SOA Key Lab ofMarine Sedimentology & Environmental Geology (MASEG200802), the Special Research Fundfor the Doctoral Program of Higher Education (20090072110004) and the Fundamental ResearchFunds for the Central University.

Photographs of short cores with sampling locations and characteristic sedimentary structures indicated(JS1–JS5, DQK1, DQK2). Green and pink circles or squares denote the sampling locations on muddy andsandy layers, respectively, with sample numbers marked nearby; horizontal pink arrows denote tidal-bore

depositional layers; green and blue arrows point to scour structures and water-escape structures,respectively; S and N represent the spring and the neap tides, respectively (in Fan et al., 2012).

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INFLUENCE OF TIDE VS WAVE ON SEDIMENT DYNAMICS AND DUNE INTERNALARCHITECTURE ON A MACROTIDAL INNER CONTINENTAL SHELF (EASTERN

ENGLISH CHANNEL)

Yann FERRET*, Sophie LE BOT**, Robert LAFITE**, Olivier BLANPAIN**, Thierry GARLAN***

*MARUM - CENTER FOR MARINE ENVIRONMENTAL SCIENCES, Leobener Strasse 2, 28359, Bremen,Germany, [email protected]**UMR CNRS 6143 M2C, UNIVERSITE DE ROUEN , Place Emile Blondel, 76821, Mont Saint Aignan,France***SHOM, 13 rue du Chatellier, 29200, Brest, France

Seabed of continental shelf environments is regularly covered with a multitude of bedformsformed in response to interactions between fluid dynamics and sediment. These mobilesedimentary features have been widely studied in order to prevent damages on human activitiesand anthropogenic structures. In coastal areas, submarine dune dynamics is mainly controlled bytidal currents and wind and wave forcings (e.g. Le Bot et al., 2004; Idier et al., 2011). However, itis generally not obvious to distinguish which forcing is predominant in dune dynamics.

In a previous study mainly based on seismic measurement analyses, Ferret et al. (2010)highlighted that both long-term tidal oscillations and inter-annual to decennial variability of stormactivity could be responsible for the dynamics and internal architecture of dunes (height: 2-10.5m,wavelength: 250-1800m) in the Eastern English Channel. If storms are considered as majorevents, authors assume that they can be strong enough to reverse dune migration direction, andform second-order erosive reflectors (Figure 1). The present study aims to verify this assumptionby quantifying the wave influence on the dynamics of heterogeneous sediment (mixture of sandand gravel). The final objective is to get wave thresholds above which an inversion of the directionof sediment transport is calculated.

For this purpose, two oceanographic surveys, conducted in 2007 and 2008, allow to realizecurrent measurements (ADP and ADV) and sediment samples, in order to calculate sedimentfluxes and to quantify sediment dynamics. In this study, only bedload sediment transport isconsidered since it is generally accepted as the dominant transport mode responsible for dunedynamics. Calculations have been realized for tide- and wave-combined conditions by using anon-uniform sediment transport formulae developed by Wu et al. (2000), and considered to be themost suitable for the heterogeneous sediments in the Channel (Blanpain, 2009).

Calculated sediment fluxes are almost only concerned with fine and medium sands. Frommeasurements, we see that storm waves (HS>2m) can: (1) initiate bedload sediment transportwhere it is inexistent under fair tidal conditions (neap tides), or (2) strongly increase the quantitiesof sands transported by tidal currents (medium sands in particular). Sediment fluxes are up to tentimes higher compared to mild conditions. Moreover, we also noted that waves can reverse thedirection of the residual sediment transport induced by tide, and subsequently be responsible forthe formation of second-order reflectors.

Strong storm events have not been experienced during this time. Indeed, significant waveheights are not very high, and wavy conditions took place only for several hours. In order toquantify the impact of waves on sediment transport, sediment fluxes have been calculated over aspring tide semi-diurnal cycle by simulating different wave conditions: Hs from 0m (tidal forcingonly) to 6m (decennial wave height). Thus, it has been possible to identify a wave heightthreshold above which direction of sedimentary fluxes is reversed: it varies from 1.7 to 2.8 m,according to the studied sector. These values are lower than local annual wave height (4.2 m),indicating that several second-order reflectors are formed per year. Compared to the formationoccurrence estimated from seismic records for second-order reflectors (4 to 18 years ; Ferret etal., 2010), it is obvious that only few of them are preserved due to strong eroded volumes.

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Example of typical dune internal architecture observed off the Normandy coast (Eastern English Channel):(A) 3•5 kHz seismic profile and (B) its interpretation. 1 and 2 indicate first- and second-order reflectors.

Blanpain, O. 2009. Dynamique sédimentaire multi-classe : de l'étude des processus à la modélisation enManche. PhD thesis, Université de Rouen. 315 pp.Ferret, Y., Le Bot, S., Tessier, B., Garlan, T. and Lafite, R. 2010. Migration and internal architecture ofmarine dunes in the Eastern English Channel over 14 and 56 year intervals: the influence of tides anddecennial storms. Earth Surface Processes and Landforms 35: 1480-1493..Idier, D., Astruc, D. & Garlan,T. 2011. Spatio-temporal variability of currents over a mobile dune field in theDover Strait. Continental Shelf Research 31 (19–20): 1955-1966.Le Bot, S. and Trentesaux, A. 2004. Types of internal structure and external morphology of submarinedunes under the influence of tide- and wind-driven processes (Dover Strait, northern France). MarineGeology, 211(1-2): 143-168.Wu, W., Wang, S.S.Y. and Jia, Y. 2000. Non-uniform sediment transport in alluvial rivers. Journal ofHydraulic Research, 38: 427-434.

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THE ORDOVICIAN TABLE MOUNTAIN GROUP, SOUTH AFRICA: THE TIDALDEPOSIT THAT NEVER WAS

Burghard W. FLEMMING

SENCKENBERG, Suedstrand 40, 26382, Wilhelmshaven, Germany, [email protected]

In the Ordovician Cape Basin, South Africa, the Table Mountain Group commences at itsbase with a ca. 800-m-thick conglomeratic coarse-grained sandstone (Piekenierskloof Formation),followed by 440 m of interbedded quartzarenites and silt-/mudstones locally containing marinetrace fossils (Graafwater Formation), and 1,800 m of medium- to coarse-grained, supermaturequartzarenites (Peninsula Formation), which frequently display floating pebbles and which areoccasionally interrupted by several decimetre-thick pebble beds. Within a few thin sequences thequartzarenites display marine trace fossils (Rust, 1973). The latter is capped by a 120-m-thicksequence comprising sandstones, conglomerates and a diamictite (Pakhuis Formation). Thesuccession as a whole has been interpreted as representing, from north to south, a progradingalluvial fan, braid plain/fan delta to shallow-marine deposit in a mesotidal setting (Fig. 1a; Visser,1974; Tankard et al., 1982), the latter being supposedly well exposed in the up to 800-m-thicksedimentary succession preserved in the Cape Peninsula which is located along the westernmargin of the Cape Basin (Tankard and Hobday, 1977; Hobday and Tankard, 1978; Tankard etal., 1982).

A closer look at the criteria, however, reveals that, as far as the exposures on the CapePeninsula are concerned, the above interpretation is mostly based on circumstantial evidence,none of the sedimentary structures described in the literature being exclusively or uniquelydiagnostic of tidal environments, although it is undisputed that sporadic trace fossils documentedfrom a few discrete horizons were produced by marine organisms. With the exception of thesehorizons, the majority of sedimentary structures and other features overwhelmingly favour analluvial braid-plain/fan-delta setting which experienced a number of marine incursions. Among thestructures and features are sand-filled mud cracks more typically associated with desiccation afterepisodic flooding rather than regular tidal emergence (Turner, 1986); the ubiquitous occurrence offloating pebbles in cross-bedded sets; the intercalation of several decimetre-thick pebble beds;stacked linguoid bars typical of distal braid-plain environments; the frequency and scale ofdeformation structures, including overturned large-scale cross-beds (up to 10 m high!); theabsence or very rare occurrence of true herringbone structures; the total absence of neap-springtidal bundle sequences even in large cross-bedded sets; and last but not least, the largethickness of the sedimentary succession which is quite atypical of tidal deposits. On account ofthese inconsistencies, the tidal origin of the lower Table Mountain Group deposits was alreadyquestioned by Fuller (1984), Turner (1986), Flemming (1988), and Hiller (1992).

In order to reconcile the entire suite of observed sedimentary structures and other featureswith an appropriate depositional environment, it is proposed that the Table Mountain Groupsediments were deposited to the south of an escarpment on a very broad (several 100 km wide),gradually sloping coastal plain with the shoreline situated south of the Cape Peninsula, but withsome deeper channels within the reach of the high tide (Fig. 1b). Initially, the coastal plain wasencroached by alluvial fans fed by material derived from Precambrian rocks exposed in the nottoo distant hinterland to the north, as revealed by the mineralogical composition. The proximal,conglomeratic deposits of these fans define the Piekenierskloof Formation. The distal parts endedin shallow, playa-type water bodies which seasonally dried up to produce the mud-crackedsuccessions of the Graafwater Formation which were capped by thin sand sheets duringsubsequent flood seasons (Turner, 1986). This basal sequence, which was occasionallyinundated by the sea, was then (quite suddenly) overridden by huge supplies of glacial outwashsands derived from the margin of the polar ice sheet which, in Ordovician times, was locatedseveral thousand kilometres to the north.

The large transport distance explains the supermature nature of the sands, while the largewater masses released from the glaciers in summer are compatible with the overall high-energydepositional character. Large downstream migrating bedforms in up to several 10s of metresdeep channels incised into the middle to distal fan-delta deposits produced the up to severalmetres thick cross-bedded sets. The distal braid-plain probably merged with the coastal ocean tothe south. Subsidence and temporary interruptions in sediment supply were associated withoccasional marine transgressions across the lower fan-delta, the invading marine organismsleaving their traces in discrete marine-influenced sedimentary successions. During Silurian timesthe southward shifting ice sheet eventually emplaced the diamictite at the top of the succession.

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a) Schematic illustration of the depositional environments proposed by Tankard et al. (1982) for the lowerTable Mountain Group sedimentary succession. b) Alternative braid-plain/fan-delta interpretation proposed

here. The Cape Peninsula would be located in a middle to distal position on the fan.

Flemming, B.W., 1988. Evidence for a fluvial rather than tidal origin of the lower Table Mountain Groupsedimentary succession (Ordovician Cape basin, South Africa). Terra Cognita, 8, p. 30.Fuller, A.O., 1984. A contribution to the conceptual modelling of pre-Devonian fluvial systems. Trans. Geol.Soc. SA. Afr. 88, 189–194.Hiller, N., 1992. The Ordovician System of South Africa: a review. In: Webbey, B.D., Laurie, J.R. (eds),Global perspectives on Ordovician geology. Balkema, Rotterdam, pp. 473–485.Hobday, D.K., Tankard, A.J., 1978. Transgressive-barrier and shallow-shelf interpretation of the lowerPaleozoic Peninsula Formation, South Africa. Geol. Soc. Am. Bull. 89, 1733–1744.Tankard, A.J., Hobday, D.K., 1977. Tide-dominated back-barrier sedimentation, early Ordovician CapeBasin, Cape Peninsula, South Africa. Sediment. Geol. 18, 135–159.Tankard, A.J., Jackson, M.P.A., Eriksson, K.A., Hobday, D.K., Hunter, D.R., Minter, W.E.L., 1982. Crustalevolution of Southern Africa – 3.8 billion years of Earth history. Springer-Verlag, New York, 523 pp.Turner, B.R., 1986. Environmental significance of desiccation cracks in the Early Ordovician GraafwaterFormation, Cape Peninsula, South Africa. Geocongress ’86, Geol. Soc. S. Afr., Extended Abstracts, pp.433–435.Rust, I.C., 1973. The evolution of the Paleozoic Cape Basin, southern margin of Africa. In: Nairn, A.E.M.,Stehli, F.G. (eds), The ocean basins and margins, I. The South Atlantic. Plenum Press, New York, pp.247–276.Visser J.N.J., 1974. The Table Mountain Group: a study in the deposition of quartz arenites on a stableshelf. Trans. Geol. Soc. S. Afr. 77, 229–237.

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OBSERVATIONAL EVIDENCE FOR THE INWARD TRANSPORT OF SUSPENDEDMATTER BY ESTUARINE CIRCULATION IN THE WADDEN SEA

Goetz FLOESER*, Hans BURCHARD**, Rolf RIETHMUELLER*

*HELMHOLTZ ZENTRUM, Max-Planck-strasse 1, 21502, Geesthacht, Germany, [email protected],[email protected]**BALTIC SEA RESEARCH INSTITUTE, Seestrasse 15, 18119, Warnemuende, Germany,[email protected]

Observational evidence is presented that corroborates several predictions of the theory ofestuarine circulation in the Wadden Sea. Current velocity data from moored ADCPs and shipcruises, turbulence measurements and SPM transport measurements from several locations inthe Wadden Sea were analyzed. As a general result, the vertical current profiles and turbulenceindicators show features concurring with the predictions of the theory. One more consequence isthat these current features must lead to a residual outflow of Wadden Sea waters in the upperpart and a residual inflow of water in the lower part of the water column, thus giving a genericexplanation for the obvious net import of suspended sediments from the German Bight into theWadden Sea.

The predictions of Burchard’s theory (Burchard, 2008) concerning estuarine circulationconcern a) current velocity profiles, b) turbulence indicators like mass diffusion and turbulentkinetic energy dissipation, c) the salinity difference between surface and bottom waters and d) theentire suspended matter transport in the water column. For all items, confirmations could befound in several locations of the Wadden Sea.

For the case of current velocity, measurements from moored (from 2002 through 2009) andship-bound ADCPs were analyzed along with conductivity and temperature measurements fromwhich the density gradient was derived. The current velocity profiles were averaged and fitted to alogarithmic function. The curvatures of ebb and flood current were used and compared to thepredictions.

Becherer et al. (2011) analyzed turbulence measurements from a campaign in the ListerDeep in April 2008 and found a confirmation of the theory’s predictions: destratification duringflood and increased stratification during ebb.

In May 2011, a ship campaign was done in the backbarrier Wadden Sea area of SpiekeroogIsland with concentrated measurements of current velocity, suspended matter and turbulencemeasurements.

With these results from several regions of the Dutch and German Wadden Sea, weconsider our hypothesis of the presence of estuarine circulation in the Wadden Sea as confirmed.Future investigations will concentrate on the effect of this kind of circulation on vertically resolvedsuspended matter transport.

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Map of the locations where data were collected in the German and Dutch Wadden Sea

Becherer, J., Burchard, H., Flöser, G., Mohrholz, V., and Umlauf, L. (2011). Evidence of tidal straining inwell-mixed channel flow from microstructure observations. Geophysical Research Letters 38, L17611Burchard, H., Flöser, G., Staneva, J.V., Badewien, T.H., Riethmüller, R. (2008). Impact of density gradientson net sediment transport into the Wadden Sea. J. Phys. Oceanogr., 38, 566-587.Flöser, G., Burchard, H., Riethmüller, R. (2011). Observational evidence for estuarine circulation in theGerman Wadden Sea. Cont. Shelf Res. 31, 1633-1639.

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EVOLUTION AND STRATIGRAPHY OF A HOLOCENE MICRO-TIDAL BARRIERSYSTEM IN THE NORTHERN WADDEN SEA

Mikkel FRUERGAARD, Thorbjørn Joest ANDERSEN, Lars Henrik NIELSEN, Peter N.JOHANNESSEN, Morten PEJRUP


IntroductionBarrier islands only occupies about 15% of the world’s coastlines but along the Atlantic and

Gulf coasts of the United States and the NW European Wadden Sea coast they are a verycommon feature. Barrier islands are considered very important areas both economically andrecreational and they are often densely populated. Many modern barrier islands may however bethreatened by the rising global eustatic sea level and there is an increasing concern for the futuredevelopment of barrier islands (FitzGerald et al., 2008). Several studies have investigated theevolution of barrier islands (e.g. Heron et al., 1984; Moslow and Heron, 1981) in relation to theHolocene sea level rise. Common for many of these studies are that 14C dating was applied toestablish the time frame of barrier island sedimentation. This is often problematic due to the lowcontent of applicable organic material in many barrier island deposits. This study uses opticallystimulated luminescence (OSL) dating, which enables direct age-determination of sandy depositsand together with sedimentological facies interpretations aims to set up a model accounting forthe development of the barrier island in relation to the Holocene sea level rise.

Research areaThe Skallingen-Langli complex is located in the Northern part of the Danish Wadden Sea

(Fig. 1). The complex consists of the NW-SE situated barrier-peninsula of Skallingen (c. 22 km2)and the smaller island of Langli (c. 1 km2) situated in the back-barrier area east of Skallingen.The area is influenced by semidiurnal tides with a mean tidal range of about 1.3 m and the westcoast of Skallingen is subject to a moderately-high energy wind climate from the North Sea with amean annual wave height of about 1 m (Nielsen and Nielsen, 2006). Extreme storms occasionallycontribute to the astronomical tidal range with more than 4 m of wind set-up.

MethodFive wells ranging in depth from 10 to 22 m were cored and 92 sediment samples were

collected to create a detailed absolute chronology using OSL dating (Madsen et al., 2005). Thismethod determines the time of the last light exposure of the sediment which generallycorresponds to the time of deposition. OSL dating is especially suited when working with sandysediments deposited within the last ~100.000 years. Sedimentological descriptions of the coreswere carried out and the interpretation of the depositional environments were based on keycharacteristics as lithology, grain-size, structures, amount of bioturbation, amount and maximumsize of pebbles and trace fossils.

ResultsBased on sediment facies logs from the core wells 10 depositional units each representing

a depositional environment have been identified in the Skallingen-Langli barrier complex. Theseare: Transgressive lag, flood tidal delta, aggradational shoal and shoreface, tidal inlet/channel,mudflat, sand flat, reed swamp/organic rich soil, washover fan, beach ridge and beach, andaeolian. The Holocene deposits overlay sandy outwash plain deposits of Pleistocene age. TheHolocene evolution of the barrier complex began with basal peat accumulation in a reed swampabout 8400 years ago. Approximately 8000 years ago the sea flooded the reed swamp andformed a transgressive flooding surface. The first transgressive lag sediments accumulated 6600years ago followed by rapid accumulation of flood tidal delta sediments until about 4500 yearsago. At core site S1 beach sediments accumulated 5000 years ago and at core site L1 flood tidalsedimentation was succeeded by beach sedimentation about 4500 years ago. Between 4500 and2000 years ago core site S2, S4 and S5 became exposed to wave erosion due to shorelinetransgression and in the same period the sedimentation at core site L1 decreased or ceased andthe site became flooded. The modern Skallingen-Langli complex formed during the last c. 1000years with back-barrier sedimentation at core site L1 followed by aeolian sedimentation from 450to 300 years ago. The modern Skallingen formed as an aggradational intertidal to supratidalmarine shoal 370 years ago possibly during or shortly after a major storm in 1634 AD. The last c.300 years washover and aeolian sediments have accumulated on Skallingen.

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Conclusions 1 A high-resolution absolute chronology has been obtained for 5 sediment cores with ages

ranging from 32300 ± 300 to 100 ± 10 years. The chronology documents the temporal evolutionfrom wide spread outwash plain to the Skallingen-Langli barrier island complex.

2 Two major surfaces have been identified in the internal architecture of the complex. Atransgressive surface formed due to the marine flooding of the pre-Holocene surface. Thissurface marks the lithological change from glacio-fluvial sand or terrestrial accumulated peat tomarine or estuarine mud and sand. The second major surface is a marine wave ravinementsurface formed by shoreline erosion due to the transgression of the shoreline and is only presentin the seaward part of the Skallingen-Langli complex.

3 The sea-level rise and rapid shoreline retreat shifted the area of sedimentation in alandward direction during the marine transgression of the low-relief Pleistocene substratumcausing a distinct time lag between flooding and the initial estuarine sedimentation.

4 The Holocene sedimentation preserved in the complex is characterised by restrictedperiods (centuries) of rapid accumulation and periods of non-deposition or erosion. Widespreaderosion was especially associated with the shoreline transgression which resulted in a largehiatus of c. 4000 years in the seaward part of the sedimentary complex.

5 The formation of the modern Skallingen may have been the result of an extreme stormimpacting the Northern Wadden Sea in 1634.

6 The application of a high resolution OSL chronology in the analysis of the evolution of theSkallingen-Langli complex has been a key tool in the identification of the depositional units andbounding unconformities due to the homogenous sedimentology characteristic for this system.The study demonstrates that small changes in lithology and structures can represent majordiscontinuities in the stratigraphy and changes in the depositional systems. A high resolutiongeochronology is therefore critical in the interpretation of complex stratigraphic architecture, in theconstruction of the sequence stratigraphic framework of barrier systems, and in the unravelmentof the sea-level history.

AcknowledgementThis study was founded by Geocenter Denmark, grant no. 603-0000 REFLEKS, by a PhD

grant from the Department of Geography and Geology, University of Copenhagen and by theDanish Council for Strategic Research grant no. 09-066869 COADAPT.

(A) Location of research area. (B) LiDAR-based digital elevation model (DEM) and Landsat image (ETM+May 31 2003). All surface elevations above 8 m DVR90 are reproduced in white in the DEM. Notice themarked terrain elevation difference between Skallingen and the area bordering Skallingen towards the

north.

FitzGerald, D.M., Fenster, M.S., Argow, B.A. and Buynevich, I.V. (2008) Coastal impacts due to sea-levelrise. Annu Rev Earth Pl Sc, 36, 601-647.Heron, S.D., Moslow, T.F., Berelson, W.M., Herbert, J.R., Steele, G.A. and Susman, K.R. (1984) HoloceneSedimentation of A Wave-Dominated Barrier-Island Shoreline - Cape Lookout, North-Carolina. Mar Geol,60, 413-434.Madsen, A.T., Murray, A.S., Andersen, T.J., Pejrup, M. and Breuning-Madsen, H. (2005) Opticallystimulated luminescence dating of young estuarine sediments: a comparison with Pb-210 and Cs-137dating. Mar Geol, 214, 251-268.Moslow, T.F. and Heron, S.D. (1981) Holocene Depositional History of A Microtidal Cuspate Foreland Cape- Cape Lookout, North-Carolina. Mar Geol, 41, 251-270.Nielsen, N. and Nielsen, J. (2006) Development of a washover fan on a transgressive barrier, Skallingen,Denmark. J Coastal Res, 1, 107-111.

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INFLUENCE OF THE TIDAL BORE ON SEDIMENT TRANSPORT IN THEMONT-SAINT-MICHEL ESTUARY, NW FRANCE

Lucille FURGEROT, Dominique MOUAZE, Bernadette TESSIER, Sylvain HAQUIN, LaurentPEREZ, Félix VIEL

UMR CNRS 6143 M2C, UNIVERSITE DE CAEN, 24 rue des Tilleuls, 14000, Caen, France,[email protected], [email protected], [email protected],[email protected], [email protected]

The Mont Saint Michel estuary is a megatidal setting (tidal range up to 14 m). It ischaracterized by a strong tidal asymmetry during spring tides, with the flood stage much shorterand quicker than the ebb, reaching commonly a velocity of 2m/s into the estuarine channels.

In estuaries with tidal ranges greater than 6 m, the difference of elevation between the risingtide and the river creates a discontinuity of velocity and pressure, called tidal bore (or “mascaret”in French). Visually, a tidal bore can be described as a wave or series of waves propagatingupstream.

This study takes place into a national project “ANR Mascaret”. Part of the field work weperformed recently on the tidal bores that propagate into the Mt St Michel estuary, aims instudying the impact of the bore fluid dynamics on sediment transport. This is an important issuefor a better understanding of the complex fluid-sediment interactions and for the operation ofrestoration of the Mont-Saint-Michel's maritime character

(http://www.projetmontsaintmichel.fr/index_uk.html). We present herein the results ofmeasurements of Suspended Sediment Concentration (SSC) sampled into the tidal bores.Previous measurements of SSC using OBS (Optical Backscattering Sensor) in the outer estuaryindicate maximum values of 6g/L close to the seafloor (Desguée et al., 2011). In order to getmore accurate values associated with tidal bore propagation into the inner estuary, we measuredSSC using different techniques (optic, acoustic, direct sampling)

The measurements were performed into the See River (View map of figure), some 8 kmupstream from the outer estuary. Velocities were measured by using ADV (Acoustic DopplerVelocimeter). For SSC estimates we used three means. SSC was measured thanks to an OBS,by direct sampling into the water column, and was calculated by acoustic inversion method (fromADV raw signals).

Manual pumps were used for direct sampling. Successive samples (less than 400ml) weretaken approximately every 30 seconds during about 5 minutes immediately after the passage ofthe tidal bore, and then every 1 to 2 minutes during the thirty following minutes. SSC were thendeduced in the laboratory after weighing and drying. ADV signal inversion is a common methodfor SSC calculation (Hosseini et al., 2006; Sottolichio et al., 2010). The critical step of the methodis the calibration phase in the laboratory. It allows correlating sediment concentration andbackscattering intensity. This is a difficult operation since the response of the ADV is verysensitive to high sediment concentrations. The OBS was calibrated in the same conditions, tocorrelate the output voltage with concentration of suspended matter.

Preliminary results demonstrate that SSC obtained by direct samplings in the water columnand ADV signal inversion are fairly different, although SSC evolution show similar patterns (Seegraphs). We assume that the problem is related to the ADV signal inversion method since directsamplings can be considered as the most reliable technique. This may be due to the properties ofthe local sediment, carbonated silt (called locally tangue) or to the high turbulence levelsgenerated by the tidal bore passage.

Anyhow, it appears that the SSC values obtained into the inner estuary are well above theaverage SSC measured by using OBS in the external estuary, i.e. 30-40 g/L vs. 6 g/L.

Complementary analyses are in course using the data of a new field survey performed inMay 2012, with simultaneous samplings at different heights in the water column. In addition toSSC estimates, grain-size analyses are also done on the samples. The objective is to defineaccurately vertical profiles of SSC and the sediment transport evolution associated with a tidalbore passage.

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Location of the study area and evolution of suspended sediment concentration (SSC) into an ondular tidalbore (top) and a breaking tidal bore (bottom) (SSC measured and SSC calculated from the amplitude of the

ADV signal)

Desguée, R., Robin, N., Gluard, L., Monfort, O., Anthony, E.J., Levoy F. (2011). Contribution ofhydrodynamic conditions during shallow water stages to the sediment balance on a tidal flat:Mont-Saint-Michel Bay, Normandy, France. Estuarine, Coastal and Shelf Science 94:343-354Hosseini, S.A., Shamsai, A., Ataie-Ashtiani, B. 2006. Synchronous measurements of the velocity andconcentration in low density turbidity currents using an Acoustic Doppler Velocimeter. Flow Measurementand Instrumentation 17: 59–68Sottolichio, A., Hurther, D., Gratiot, N., Bretel, P. 2011. Acoustic measurements of turbulence in highlyturbid waters of a macrotidal estuary. Continental Shelf Research:31:S36-S49.

50


THE 18.6 YEAR TIDAL CYCLE INFLUENCE ON THE COUESNON RIVERBEHAVIOUR, MONT-SAINT-MICHEL BAY (FRANCE)

Lucile GLUARD, Franck LEVOY

UMR CNRS 6143 M2C, UNIVERSITE DE CAEN, 24 rue des Tilleuls, 14000, Caen, France,[email protected], [email protected]

River meandering in fluvial environment are well documented. But few studies describe theirbehaviour in salt marches areas where both tidal currents and river discharge were the mainacting processes (Fagherazzi et al., 2004). This study aims at a better understanding of theirbehaviour on sand flat surfaces, through the example of the Couesnon river that wander at thefoot of the Abbey, in the inner part of the Mont-Saint-Michel Bay. Such results are useful in theactual context of coastal anthropisation, or in a local context, to help stake-holders in the projectof re-establishment of the marine nature of the Mont-Saint-Michel.

A large aerial or satellite image dataset from 1969 to 2007, and a DEM constructed from aLiDAR survey in February 2009, are used to observe the channel position of the river at eachdate. Those positions are linked to annual high tide levels, annual river discharges and wind data.The analysis of the Couesnon channel migration shows that the river changes its channelplanform in a global dynamic, well correlated with the 18.6 year lunar nodal tidal cycle, called theSaros cycle. When the channel migrates to the East, the Saros cycle is on an ascendant phase.When the channel migrates to the West, the Saros cycle is on a descendant phase. Extreme Eastor West positions of the river channel take place during high or low phases of the Saros cycle,respectively.

This dynamic reflects the sedimentary inputs variation that contributes to a sand bankchanges, in the West side of the study site. This sand bank grows and moves to the East duringan ascendant phase of the 18.6 year lunar nodal tidal cycle. Its location forces the Couesnonchannel to migrate to the same direction. During the descendant phase of the Saros cycle, thesand bank loses its influence, and the Couesnon channel answers to intern parameters, inparticular river discharge. Regardless of the Saros cycle phase, at medium time scale (i.e. year tofew years), the discharge controls also the sinuosity of the channel planform. The influence of the18.6 year lunar nodal tidal cycle has already been described in salt marsh environments (Wells etColeman, 1981; Oost et al., 1993; Dronkers, 2005; Gratiot et al., 2008; Weill et al., 2011).However, this is a result to the local site of the Mont-Saint-Michel Bay that contributes to theunderstanding of its global functioning.

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Extreme Couesnon channel locations. a/ channel and salt marsh locations in 1980; b/ channel and saltmarsh locations in 1989; c/ channel and salt marsh locations in 1995; d/ channel and salt marsh locations in

2003. MSM : Mont-Saint-Michel Abbey.

Dronkers J. (2005). Natural and human impacts on sedimentation in the Wadden Sea: an analysis ofhistorical data. Rapport du Ministerie van Verkeer en Waterstaat, 51 p.Fagherazzi S., Gabet EJ, Furbish DJ. (2004). The effect of bi-directional flow on tidal channel planforms.Earth Surface Processes and Landforms 29, p. 295-309Gratiot N., Anthony EJ., Gardel A., Gaucherel C., Proisy C., Wells JT. (2008). Significant contribution of the18,6 year tidal cycle to regional coastal changes. Nature geoscience1, p. 169-172Oost AP., de Haas H., Ijnsen F., van der Boogert JM., de Boer PL. (1993). The 18,6 yr nodal cycle and itsimpact on tidal sedimentation. Sedimentary Geology 87, p. 1-11Weill P., Tessier B., Mouazé D., Bonnot-Courtois C., Norgeot C. (2011). Shelly cheniers on a macrotidal flat(Mont-Saint-Michel Bay, France)- Internal architecture revealed by ground penetrating radar. SedimentaryGeology (in press)Wells JT., Coleman JM. (1981). Periodic mudflat progradation, northeastern coast of south america : ahypothesis. Journal of Sedimentary Petrology 51 (4), p. 1069-1075

52


ASSESSMENT OF SILTATION AT THE DREDGED CHANNEL IN THEHUANGMAOHAI ESTUARY, PEARL RIVER DELTA, CHINA

Wenping GONG

SCHOOL OF MARINE SCIENCE, SUN YAT-SEN UNIVERSITY, 135 of Xingangxi Road, 510275,Guangzhou, China, [email protected]

The Huangmaohai Estuary is located in the southwest part of the Pearl River Delta, one ofthe fastest developing regions in China. The estuary features a large open water body, relativelydeep navigation channel, and sheltered environment from wave attack, which makes it an idealplace for harbor construction. A draft plan is being undertaken to deepen its navigation channelfrom 7 m to 12.5m due to the development of large vessels for transportation. The assessment ofchanges in hydrodynamics, saline intrusion and sediment transport is a necessity for theenvironmental concern, and also the prediction of siltation situation after this expansion is ofgreat importance for the maintenance of the drafted deep channel.

In this study, a three-dimensional baroclinic model EFDC (Environmental Fluid DynamicsCode, the model domain is shown in Fig .1) is utilized to investigate the changes inhydrodynamics and sediment transport, induced by the planned project. The model is modified toaccount for the combined effect of wave and currents. After careful calibration and verification interms of water level, water current, salinity and suspended sediment concentration in dry and wetseasons, the model is applied to study the siltation under different scenarios of channeldeepening. The results indicate the importance of baroclinic effect on circulation, convergence ofsediment transport and siltation at the channel. The inclusion of wave effect is also shown to becritical for sediment resuspension at the shoals and sedimentation at the channel, especiallyduring storm conditions.

The siltation in the channel is unraveled to show large seasonal variability and is mainlyassociated with the changes in external forcings and the associated sediment load. In the wetseason, large sediment load from the upstream, combined with the establishment of strongbaroclinic circulation, cause the majority of the siltation in the channel, among which storm effectplays an important role. In the dry season, with decreasing of the sediment load, and enhancedwind and wave, the channel is shown to be under erosion.

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The study site and model grid

Hamrick, J.M., 1992. A three-dimensional environmental fluid dynamics computer code: theoretical andcomputational aspects. Special Report 317. Virginia Institute of Marine Science, Gloucester Point, VA.Hamrick, J.M., 1996. User's manual for the environmental fluid dynamics computer code. Special Report331. Virginia Institute of Marine Science, Gloucester Point, VA.

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SEDIMENTOLOGY AND SEQUENCE STRATIGRAPHY OF THE FLUVIAL-TO-TIDALTRANSITION ZONE IN THE UPPER LAJAS FORMATION (NEUQUEN BASIN,

ARGENTINA)

Marcello GUGLIOTTA*, Stephen FLINT*, David HODGSON**, Gonzalo VEIGA***

*SCHOOL OF EARTH, ATMOSPHERIC & ENVIRONMENTAL SCIENCES, UNIVERSITY OFMANCHESTER, Oxford Road, M13 9PL, Manchester, Uk, [email protected]**SCHOOL OF ENVIRONMENTAL SCIENCE, UNIVERSITY OF LIVERPOOL, 4, Brownlow Street, L693BX, Liverpool, Uk***CENTRO DE INVESTIGACIONES GEOLOGICAS (UNIVERSIDAD NACIONAL DE LA PLATA –CONICET), Calle 1 N°644, B1900TAC, La Plata, Argentina

The change from fluvial to estuarine settings is marked by the interaction of unidirectionalfluvial currents and tidal currents. In modern systems the sedimentary process changes in thetransition zone can be monitored. However, our understanding of how the fluvial-to-tidal transitionzone is recorded in stratigraphic successions is poorly constrained. The lower reaches of manyrivers are influenced by marine process, including tidal currents and brackish water. Because theresulting interaction of fluvial and marine processes occurs in low-lying areas near the coast,there is a high likelihood that these facies will be preserved in many sedimentary basins. Thisstudy is focused on the sedimentological characteristics of the fluvial-to-tidal transition zone inorder to develop a better set of criteria for determining palaeogeographic position. Specific pointsto be addressed include: how does grain size change through the transition?; in what order do thevarious marine indicators begin to be expressed moving down palaeoriver?; how does thetransition change as a function of parasequence stacking pattern (forward-stepping vsaggradational vs back-stepping)?

Preliminary results from a detailed outcrop case study of the Middle Jurassic LajasFormation of the Neuquén Basin are presented. The Lajas Formation comprises about 600 m ofsuccession, spanning approximately 4.5 My and it is distinctive as tide-influenced sedimentationpersisted through complete base level cycles and was not restricted to transgressive systemstracts or to the fills of incised valleys (McIlroy et al., 2006).

The Lajas Formation contains fluvial deposits and is overlain transitionally by the fluvialChallacó Formation, providing an ideal opportunity to explore the stratigraphic distribution ofpreserved sedimentary facies, and reservoir and seals, in the fluvial-to-tidal transition.

The study is focused initially on the “Bajada de los Molles” area, in which the transitionbetween tidal and fluvial deposits is clearly and continuous exposed for about 0.5 km along theoutcrop. Several erosion surfaces, correlatable across the entire outcrop, mark abruptstratigraphic changes in facies that allow interpretations of changes in palaeoenvironment.Multiple measured sections have been correlated to constrain strike-parallel change in facies.

In general, tidal and fluvial channel deposits are characterized by rather different grain sizeranges. Tidal channels are filled by fine to medium sandstone and some abandoned mud-filledchannels are also present. Fluvial channel fills are coarser (medium to coarse sandstone) andmay have basal pebbles layers. Palaeocurrent data indicate westerly flowing rivers but themarginal marine/marine deposits show a wide range of paleocurrent directions and scales ofcrossbedding. Generally the Lajas Formation prograded from the southern and the easternmargins of the basin, but the subordinate tidal current and wave processes generatedcentimetre-scale cross-bedding in different directions.

As well as grain size and palaeocurrents additional indicators allow the distinction offluvial-dominated from tidal-dominated deposits and better define the range of the fluvial-to-tidaltransitional zone. These indicators include tidal bundles, drapes of mud and coaly material, shells,bioturbation (marine) and large-scale cross bedding, abundant silicified wood, plant debris andthin carbonaceous shales (fluvial).

ACKNOWLEDGEMENTSThis work is part of the LAJAS Project, a joint study by the Universities of Manchester,

Liverpool, University of Texas at Austin and Queen's University, Ontario. The project is sponsoredby BHPBilliton, Statoil, VNG Norge and Woodside

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The “Bajada de los Molles” outcrop (40 Km South of Zapala) showings the upper part of the LajasFormation an excellent example of fluvial-to-tidal transitional facies.

MCILROY, D., FLINT, S.S., HOWELL, J.A. & TIMMS, N.E. 2006. Sedimentology of the tide dominatedLajas Formation, Jurassic, Neuquén Basin, Argentina. In: VEIGA, G. D., SPALLETTI, L.A., HOWELL, J.A.& SCHWARZ, E. (eds) The Neuquén Basin: a Case Study in Sequence Stratigraphy and Basin Dynamics.Special Publication of the Geological Society, London, 252, 83-107.

56


THE EFFECT OF HIGH-ENERGY EVENTS ON EBB-TIDAL DELTA SEDIMENTOLOGYAND MORPHOLOGY – A PROCESS-BASED MODEL STUDY

Gerald HERRLING, Christian WINTER

MARUM - CENTER FOR MARINE ENVIRONMENTAL SCIENCES, Leobener Strasse 2, 28359, Bremen,Germany, [email protected], [email protected]

The environment of ebb-tidal deltas between barrier island systems is characterized bycomplex morphology with tidal sand bars and shoals bordering the main channel, near-shoreoblique sand bars and shoreface-connected ridges (FitzGerald et al., 1984). These morphologicalfeatures are in a dynamic equilibrium with the prevailing hydrodynamic forces and revealcharacteristic surface sediment grain-size distributions. In this study the western tidal inlet and theshoreface of an East Frisian barrier island in the southern North Sea, has been chosen as anexemplary study area for an identification of relevant hydrodynamic drivers of ebb-tidal deltamorphology and sedimentology. ANTIA (1993) studied the shoreface-connected ridges offSpiekeroog island with lengths of more than 10km and heights of up to 6m that are aligned withthe direction of major storms (NW-SE). Surface sediments at the crests and upper seawardslopes are characterized by fine to medium sands, while coarser grain sizes are found in thetroughs - in contrast to the contrary sedimentological patterns of near-shore tidal sand bars. SONet al. (2011) showed that surface sediments of the ebb-delta shoal, the swash bars and the inletchannel are characterized by medium sands with a fair amount of coarser shell hash. Bothauthors suggest that high-energy storm conditions play a significant role on sediment dynamicsand morphology. This hypothesis has been tested in this study. By application of a process-basedmorphodynamic model the effect of high-energy events and long-term fair-weather conditions on(1) morphological changes and (2) the spatial surface sediment grain-size distribution has beendifferentiated.

Model simulations have been carried out to compare the effect of an exemplary major stormsurge event in the North Sea (Nov. 9th 2007) and a period of representative fair-weatherconditions. A fully coupled, three-dimensional, multi-fractional morphodynamic model (Delft3D,Deltares) was set-up with a high spatial-resolution grid size of 30-60m. The interaction of waveforces, tidal currents and bed evolution is realized by fully bidirectional-coupled wave-currenttransport simulations. A bed layer model (van der Wegen et al., 2011) is applied permitting there-distribution of multiple sediment fractions in accordance to the imposed hydrodynamic forces.The model simulation was started with a uniform distribution of five sand fractions with grain-sizesof 150, 200, 250, 350 and 450 microns throughout the model domain. Each sand fractiondepletes or increases in the bed cell according to erosion or deposition processes in the sedimenttransport formulation (van Rijn, 1993). Very fine sands (<150 µm) and cohesive sediments are notimplemented and thus no morphological changes and grain-size sorting takes place on theback-barrier tidal flats.

Mid-term (6 months) fair-weather model simulations suggest that for these conditionssignificant morphodynamics occur at the tidal inlet, at shore-oblique sand bars and due tosurf-zone bar dynamics, but not at all at the shoreface-connected ridges. In the inlet, fair-weathertidal currents are strong enough to remove finer sediments, resulting in a coarsening of the inletchannel. Extreme-event simulations of a single storm show much higher morphological impacts:At the ebb-tidal delta, morphological changes are in the order of 1-2m. Fine sands are stirred-upby waves and are drifted eastwards by wave-induced long-shore currents. Shore-oblique sandbars connecting the ebb-tidal delta with the downdrift surf-zone migrate eastward under stormconditions. Here, modeled surface sediment composition shows pattern of medium sands on thecrests and fine sands in the troughs. Contrariwise, at the shoreface-connected ridges fine-grainedsand fractions are eroded at the troughs and are transported over both lateral slopes to thecrestline (Fig.1). This positive morphological feedback increases the ridges’ height by severalcentimeters.

In contrast to simulations of fair-weather conditions, the model predicted re-distribution ofsurface sand grain-sizes under high-energy conditions agrees well with the observations ofANTIA (1993) and SON et al. (2011). Thus it can be confirmed that the morphology of the studiedenvironment is dominantly controlled by north-westerly waves during high-energy events.Furthermore, it is concluded that the surface sediment grain-size sorting and re-distributionprocesses are also dominantly attributed to high-energy conditions.

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The model predicted re-distribution of five surface sand fractions between 150 and 450 microns allows theevaluation of the 50% sediment grain-size percentile (d50 in µm); very fine sand fractions and cohesive

sediments were excluded in the present study, thus no grain-size sorting was modeled on the back-barriertidal flats.

Antia E.E. (1993): Surficial grain-size statistical parameters of a North Sea shoreface-connencted ridge:patterns and process implication, Geo-Mar Lett. 13: 172-181.FitzGerald DM., Penland S., Nummedal D. (1984): Control of barrier islands shape by inlet sedimentbypassing: East Frisian Islands, West Germany. Mar. Geol. 60: 355-376.Son C.S., Flemming B.W., Bartholomä A. (2011): Evidence for sediment recirculation on an ebb-tidal deltaof the East Frisian barrier-island system, southern North Sea, Geo-Mar Lett. 31: 87-100.Van Rijn L.C. (1993): Principles of Sediment Transport in Rivers, Estuaries and Coastal Seas. AquaPublications, The Netherlands.Van der Wegen M., Dastgheib A., Jaffe B.E. (2011): Bed composition generation for morpho-dynamicmodeling: case study of San Pablo Bay California, USA, Ocean Dynam. 61: 173-186.

58


TIDALLY RELATED HETEROGENITIES IN SANDBODIES SOUGHTPARAMETERIZED FOR REFINED RESERVOIR MODELLING

Berit HUSTELI, Maria JENSEN, Snorre OLAUSSEN

UNIS, C/o Unis pb 156, 9171, Longyearbyen, Norway, [email protected]

Beneath Longyearbyen, in Central Western Svalbard, an Upper Triassic to Lower Jurassicreservoir is targeted to store CO2 produced by the local energy plant. The 700 – 1000 m deeplocation of the reservoir will allow the gas to remain in its fluid state. To ensure the success andsafety of the future storage, detailed modeling of the fluids future behavior is needed.Sedimentary heterogenities is difficult to include in the current practice of reservoir modeling. Thisproject will, through detailed core and outcrop analysis coupled with Lidar data, contribute toimprove future reservoir modeling and fluid behavior prediction. Additionally, it will contribute to arefined understanding of the sedimentary environment that prevailed in the Svalbard archipelagoduring the Triassic and Early Jurassic.

Detailed core descriptions will be presented, in addition to outcrop studies of equivalentrocks ten kilometres north of the proposed point of injection. Edgeøya, east of Spitsbergen will bethe focus of fieldwork in equivalent strata in August 2012. The facies distributions will becompared with Tertiary deposits and other deposits of similar origin for a better understanding ofthe dynamics of such an environment. The results will provide an overview of the range of varietythat can be expected from these marginal marine sedimentary successions influenced by tidalenergy fluctuations. The identified variation in geometry, grain size and porosity/permeability willyield quantified parameters that can be applied to develop a reservoir model which cansuccessfully forward, and reverse model the targeted CO2 reservoir.

The study is part of the project Geological input to Carbon storage (GeC) andLongyearbyen CO2 project. The Climit program of the Norwgian Research Council funds thestudy. The results will be presented in publications as part of a PhD terminating in March 2015.

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Correlation of retrieved cores from the CO2-storage project. The upper sandbody from Triassic/LowerJurassic is the targeted reservoir.

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LATE MIOCENE INCISED VALLEY-FILL IN EASTERN TAURIDES, TURKEY:DEPOSITIONAL EVOLUTION IN RESPONSE TO SEA-LEVEL CHANGE AND

DEPOSITIONAL PROCESSES

Ayhan ILGAR, Erol TIMUR, Erhan KARAKUS, Serap KAYA, Banu TURKMEN

GENERAL DIRECTORATE OF MINERAL RESEARCH AND EXPLORATION, Balgat, 06520, Ankara,Turkey, [email protected]

The incised valley-fills located within the reefal limestones of Middle Miocene age crop outin the southwestern part of the Adana Basin in eastern Taurides (Figure 1A, B). These depositsshow funnel-shaped geometry extending 18 km in north-south direction. The valley-fill depositscomprise wide variety of facies types and composed of five facies associations includingbay-head delta, tidal-flat, central basin lagoon, ebb-tidal delta and barrier-island. Based on thesefacies associations, the valley-fill is regarded as the typical microtidal wave-dominated estuary.

Bay-head delta deposits which are located on the landward edge of the estuary to the north,consist of fluvial topset and basinward inclined foreset beds of conglomerates (Figure 1C). Thesediments of the delta are mainly derived from the pre-estuarine reefal limestones. The tidal-flatsediments, which are also situated on the northern margin of the incised-valley, are composed ofmudstones, siltstones, sandstones and subordinate conglomerates. These deposits show flaser,lenticular and wavy bedding, planar paralel stratification, current ripples, bi-directional crossstratification and well-sorted point bar deposits of tidal channels (Figure 1D). The central basinlagoon deposits mainly comprise the bioturbated, massive mudstones and subordinate lenticularsiltstones (Figure 1E). The ridge-shaped barrier-island deposits which extend in east-westdirection, are located on the southern part of the incised-valley. These deposits consist of planarparalel stratified, well sorted coarse sandstones and granule conglomerates (Figure 1F). Theebb-tidal delta deposits which are composed of fine to coarse sandstones, developed in thebasinward side of the barrier-island. These deposits are characterized by planar cross-stratifieddunes (Figure 1G) and tidal channel deposits, up to 60 cm and 190 cm in thickness, respectively.The mammalian fossil of Tetralophodon longirostris found in ebb-tidal delta deposits indicates aLate Miocene (early-middle Turolian (MN 11-12) age.

The Neogene palaeogeographic evolution of the Adana Basin were greatly controlled by therelative sea-level changes. The interruption of marine sedimentation related to the falling ofsea-level in eastern Taurides occurred at latest Middle Miocene. This event exposed the depositsof reefal limestones and caused to the formation of incised-valleys by fluvial erosion in thesouthwestern part of the Adana Basin. Subsequent marine flooding during the early Late Miocenesea-level rise converted the incised-valley into an wave-dominated estuarine environment in theregional microtidal setting of Miocene Mediterranean. The wave processes controlled thedeposition by constructing a barrier-island at the mouth of the incised-valley which caused to theformation of a sheltered environment behind the barrier-island. The mudstones of the centralbasin lagoon deposited on this protected environment. The bay-head delta prograded southwardfrom the landward edge of the estuarine to the central basin lagoon. In spite of the low tidal rangeof microtidal setting, the confinement of the tidal currents within the incised-valley caused to theenhancement of the tidal wave. So, the sufficient tidal prism provided tidal sedimentation in theincised-valley as tidal-flat and ebb-tidal delta deposits. It is thought that the ebb-tidal deltadeposits were protected from the strong wave or storm erosion by confinement in theincised-valley.

61


(A) Topographic map of Anatolia, showing the major tectonic boundaries and location of the Adana Basinbetween Taurus Orogenic Belts to the northwest and Misis Structural High to the southeast. (B) Simplifiedgeological map of the Mut and Adana basins, showing the position of the wave-dominated estuary at the

southwestern part of the Adana Basin. (C) Bay-head delta deposits consist of fluvial topset and basinwardinclined foreset beds of conglomerates on the central basin lagoon mudstones. (D) The tidal-flat sediments

are composed of flaser, lenticular and wavy beddings, planar paralel stratification, current ripples,bi-directional cross stratification and well-sorted point bar deposits of tidal channels. (E) The central basin

lagoon deposits mainly comprise the bioturbated, massive mudstones and subordinate lenticular siltstones.(F) The ridge-shaped barrier-island deposits consist of planar paralel stratified, well sorted coarse

sandstones and granule conglomerates. (G) The ebb-tidal delta deposits which developed in the basinwardside of the barrier-island, are characterized by planar cross-stratified dunes and tidal channel deposits.

62


THE VARIABILITY OF ESTUARINE DEPOSITS IN A MICROTIDAL SETTING OF LATEMIOCENE MEDITERRANEAN (EASTERN TAURIDES, TURKEY): CONTROLLING

FACTORS ON DEPOSITION

Ayhan ILGAR, Erhan KARAKUS, Tolga ESIRTGEN

GENERAL DIRECTORATE OF MINERAL RESEARCH AND EXPLORATION, Balgat, 06520, Ankara,Turkey, [email protected]

The Adana Basin is one of the largest Neogene basin which is located on the northeasternedge of the Mediterranean in southern Turkey formed between the Taurus Orogenic Belts to thenorthwest and Misis Structural High to the southeast (Figure 1A). The latest Middle Miocenesea-level fall caused to the formation of incised-valleys in different part of the Adana Basin whichwere filled by discrete facies associations of fluvial to estuarine settings during the subsequentsea-level rise.

The incised-valleys show funnel-shaped geometry extending in north-south direction.Although the incised-valleys were situated in the same coast of the basin in the earliest LateMiocene, two contrasting estuarine sediments were deposited on these valleys. One of them consisting of bay-head delta, tidal-flat, central basin lagoon, ebb-tidal delta and barrier-islandfacies associations reflects a wave-dominated estuarine setting in the western part of the basin(Figure 1B). The other incised valley-fill is located 55 km to the east of the basin (Figure 1B) andstarts with the fluvial deposits of meandering rives at the bottom of the valley. Fluvial sandstonesand mudstones are overlain by fine to very coarse grained marine sandstones rich in oysterfossils at the boundary. The marine sandstones include amalgamated trough and planarcross-stratifications, sigmoidal beds, lateral accretion sand bodies and isolated herringbonecross-stratifications which forming sand bars. The dunes, up to 150 cm in thickness, show mainlybi-directional bar developments bounded by reactivation surfaces with fine pebble pavement andthin bedded parallel stratified sandstones between them (Figure 1). These features of tidal duneand bars are confined in an incised-valley and form a tide-dominated estuarine deposits.

The coeval occurrence of the wave- and tide-dominated estuarine deposits in a microtidalpalaeo-oceanographic setting of Mediterranean in Late Miocene reflects an importantpalaeogeographic and structural implications. The western incised-valley was open to the normalmarine processes and the deposition was controlled by the wave action at the mouth of the valleyand fluvial processes at the head of the estuary. Tidal processes relatively little affected thesedimentation and caused the deposition of the ebb-tidal delta and tidal-flat sediments. However,the tidal processes were the main controlling factor on eastern incised-valley. This distinctionoccurred related to the enhancement of the tidal prism on eastern estuarine which was located atthe northern margin and inner part of the Adana Basin embayment. This embayment wastectonically constructed by Misis Structural High which protected the deposits in Adana Basinfrom erosional effects of strong wave and storm action. The development of the embayment alsocaused to a resonance and consequent amplification of the tidal wave which was resulted in atide-dominated estuarine of a microtidal setting in the incised-valley.

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(A) Topographic map of Anatolia, showing the major tectonic boundaries and location of the Adana Basinbetween Taurus Orogenic Belts to the northwest and Misis Structural High to the southeast. (B) Simplifiedgeological map of the Mut and Adana basins, showing the positions of the wave-dominated estuary at the

southwestern part of the Adana Basin and tide-dominated estuary at the northern margin of the MiddleMiocene Adana Basin embayment. (C, D, E, F, G) Tidal dunes and sand bars formed by various types of

trough and planar cross-stratifications. These tidal bars are confined in an incised-valley and formtide-dominated estuarine deposits.

64


SEDIMENTOLOGY OF A FLUVIALLY DOMINATED, TIDALLY INFLUENCED POINTBAR: THE LOWER CRETACEOUS MIDDLE MCMURRAY FORMATION, LOWER

STEEPBANK RIVER AREA, NORTHEASTERN ALBERTA, CANADA

Bryce JABLONSKI*, Robert W. DALRYMPLE**

*HEAVY OIL TECHNOLOGY CENTRE, STATOIL CANADA, 3600, 308-4 Ave. sw, T2P 0H7, Calgary,Canada, [email protected]**DEPARTMENT OF GEOLOGICAL SCIENCES, QUEEN'S UNIVERSITY, Miller Hall, K7L 2E2, Kingston,Otario, Canada, [email protected]

The Lower Cretaceous (Aptian-Albian) McMurray Formation exposed along the lowerSteepbank River in northeastern Alberta, Canada, exhibits world-class examples of inclinedheterolithic stratification (IHS; Thomas et al., 1987) that is formed of alternating sand and mudlayers. Individual sand layers reach 30 cm thick and consist of fine-grained sand that containsunidirectional climbing current-ripple lamination and, less commonly, dune-scale cross bedding. There is no evidence of tidal activity in most beds, but thin silt drapes are present in rare cases. Bioturbation is typically absent, but some beds contain scattered vertical burrows (Cylindrichnuspredominates), or discrete layers with abundant burrows that are interpreted to representamalgamation of two sand beds. These attributes indicate that the sand beds were depositedrapidly by river floods, in water that was either fully fresh or only very slightly brackish. Theintervening mud layers range from less than a centimeter to approximately 10 cm in thickness. Incontrast to the sand layers, they are intensely burrowed (again Cylindrichnus predominates, withlesser numbers of Planolites and Gyrolithes). Tidal-rhythmite lamination is visible in someoccurrences where lamination has not been obliterated by burrowing. These fine-grained bedswere deposited during times of low river discharge, under conditions of weak to moderate tidalactivity. The water was brackish, but the very restricted ichnological diversity indicates thatsalinity levels were low. Each sand-mud couplet is, thus, interpreted to represent one year.

These couplets are organized into a larger-scale cyclicity termed “meter-scale cycles”(MSCs; thicknesses 0.5-3 m). The basal part of each cycle consists of amalgamated sand layers,whereas the upper part of a cycle contains thicker mud interbeds. The thickness of the sandbeds decreases upward through a cycle. The number of recognizable sand beds within thesecycles ranges from 3-20. These cycles are thus “decadal” in duration and presumably reflectinterannual variations in river discharge. These MSCs are an important architectural element ofthese point bars and can be correlated over long distances around each bend.

Previous workers have interpreted these outcrops as having accumulated in an “estuarine”environment. We believe that they were formed in the fluvially dominated, tidally influencedportion of the tidal-fluvial transition (Fig. 1; i.e., in the innermost part of the transition). This isbased on the fact that river-flood deposits are volumetrically predominant in the succession, andthat river-flood deposition occurred under conditions of essentially unidirectional flow and nearlyfresh water. Tidal action and brackish-water conditions only penetrated this far up the river duringtimes of low river discharge. We suggest that the presence of a clear river-generated seasonalityin a deposit is an indication that deposition occurred in a fluvially dominated setting. As onemoves seaward through the fluvial-marine transition, one can expect this river-generatedseasonality to decrease in prominence, while features generated by marine processes (e.g., tidalsedimentary structures and bioturbation) increase in abundance (Fig. 1).

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Schematic map of the fluvial-tidal transition displaying the variation in depositional conditions and structuresas a function of the relative importance of fluvial and tidal energy. Through the transition, there is a changein the relative abundance of tidal sedimentary structures (e.g., tidal bundles, tidal rhythmites), the amount of

bioturbation, and the prominence of bedding related to seasonal variations in river discharge. Themigration of the salinity and tidal nodes (i.e., the limit of salinity and tidal intrusion up the river) in response

to seasonal variations in river discharge is also shown.

Thomas, R.G., Smith, D.G., Wood, J.M.,Visser, J., Calverley-Range, E.A., Koster, E.H., 1987. Inclinedheterolithic stratification -terminology, description, interpretation and significance. Sedimentary Geology v.53, pp. 123–179.

66


THE TIDALLY-INFLUENCED RIVER DEPOSITS OF THE PLEISTOCENE SEINESYSTEM: THE EXAMPLE OF THE TOURVILLE-LA-RIVIERE TERRACE (NW

FRANCE)

Guillaume JAMET*, Olivier DUGUE*, Bernard DELCAILLAU*, Dominique CLIQUET**

*UMR CNRS 6143 M2C, UNIVERSITE DE CAEN, 24 rue des Tilleuls, 14000, Caen, France,[email protected], [email protected], [email protected].**DRAC SRA, 13 Bis, rue Saint-Ouen, 14000, Caen, France, [email protected]

Since the 20th century, the Pleistocene Seine terraces system from Les Andelys to LeHavre was mainly studied using geomorphological tools (Lautridou et al., 1999). The lower SeineValley was formed by the Plio-Pleistocene fluvial incision and shows presently large enclosedmeanders. Few studies focused on fluvial to tidal environment transition during Pleistocene. Anunderstanding of both continental and marine processes at the lower Seine Valley scale isneeded to comprehend the stepped terraces system. On the one hand, the Seine River hasincised a 125 m-deep and 2-4 km-wide valley. The substratum is composed of Cretaceous chalkswith flints overlain by an irregular Cenozoic sedimentary cover (clay-with-flints and sands) andPlio-Pleistocene fluvio-marine facies (Lozere sand Formation and Saint Eustache sandFormation). The braided Pleistocene Seine River flow was able to erode, transport and reworkbed material over large distances. On the other hand, alternating glacial and interglacialconditions during the Pleistocene period resulted in large shoreline fluctuations between thecoastal watersheds of the Bay of Seine (Seine, Touques, Dives and Orne) and the Channel.During the interglacial periods (i.e., Marine Isotopic Stages 5e, 7 or 11), several marine incursionsoccurred along different courses of the Seine fluvial system. Consequently, the Pleistocene SeineValley started to trap silty and sandy sediments supplied by the river.

New sedimentological investigations on the Tourville-la-Rivière low terrace were conducted100 km away from the Seine estuary. Such sedimentary studies based on recently-discoveredoutcrop profiles exhibit mixed fluvial and tidal deposit that settled down during the MiddlePleistocene. The lower unit (fig.) of the vertical sequence shows 6 to 8 m-thick fluvial depositsoverlying the Senonian chalky bedrock (± 4 m NGF). These deposits are mainly composed ofcoarse sands and gravels organised in fluvial bars. The latter fluvial architecture corresponds to abraided river system. This alluvial sequence is overlain by sands with flazer and wavy beddings (±13 m NGF) and a well-developed pedocomplex closed to a schorre system. The middle unit ischaracterized by homogeneous tidal sand deposits previously interpreted as fluvial environment(± 20 m NGF) (Lautridou et al., 1984). The upper unit evolves toward a slope deposits composedof sands, local head deposits and palaeosols (reworked Eemian Bt horizon, present-day soil).This sedimentological change in fluvial architecture started by high river discharges underperiglacial conditions followed by the drowning of the Seine valley. Those new investigationscomplemented by numerical dating (IRSL, 196 ±23 ka BP; e.g. Balescu et al., 1996) and resultsof previous palaecological data, have allowed to discuss the cut-and-fill terrace processes of theSeine River during the Saalian (MIS 7). Those important results can be used to improve thepalaeogeographic reconstruction of the Seine River during the Quaternary.

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Evolution of the fluvial-tidal transition units during MIS 7: The Tourville terrace (NW France)

Balescu S., Lamothe M., Lautridou J.-P., 1996 - Luminescence evidence of two Middle PleistoceneInterglacial events at Tourville (Northern France). Boreas, 26, p. 61-72.Lautridou J.-P., Lefebvre D., Lécolle F., Carpentier G., Descombes J.-C., Gaquerel C., Huault M.-F., 1984 -Les Terrasses de la Seine dans le méandre d’Elbeuf, corrélations avec celles de la région de Mantes.Bulletin de l’Association Française pour l’Etude du Quaternaire, 1.2.3, p. 27-32.Lautridou J.-P., Auffret J.-P., Baltzer A., Clet M., Lécolle F., Lefèbvre D., Lericolais G., Roblin-Jouve A.,Balescu S., Carpentier G., Cordy J.-M., Descombes J.-C., Occhietti S., Rousseau D.-D., 1999 - Le fleuveSeine, Le fleuve Manche. Bulletin de la Société Géologique de France, 170, (4), p. 545-558.

68


THE SEDIMENTARY DEVELOPMENT OF A HOLOCENE TO RECENT BARRIERISLAND, DANISH WADDEN SEA

Peter N. JOHANNESSEN, Lars Henrik NIELSEN, Ingelise MØLLER, Lars Henrik NIELSEN,Thorbjørn Joest ANDERSEN, Morten PEJRUP


The Rømø barrier island is situated in the northern part of the European Wadden Sea. Ithas been intensively studied on the basis of recent depositional systems and morphology, seven25 m long sediment cores, 35 km ground penetrating radar (GPR) reflection profiles with amaximum signal penetration of c. 15 m and a resolution of c. 20–30 cm (Nielsen et al., 2009), anddating of 70 core samples using optically stimulated luminescence (OSL).

The area has experienced a relative sea-level rise of c. 15 m during the last c. 8000 years.The Recent tidal amplitude reaches c. 1.8 m. During strong wind set up the water level increasesconsiderably and the highest measured water level is 4.9 m above mean sea level.

The barrier island is c. 14 km long and c. 4 km wide and is separated from the mainland bya c. 8 km wide lagoon. At the northern and southern parts of the island, tidal inlets occur with awidth of 400–1000 m and depths of 7–30 m. Salt marsh areas, up to 2 km wide, are fringing thelagoonal coast of the island. Active eastward migrating aeolian dunes cover large parts of theisland.

The Rømø barrier island system is a very sand rich system as it receives coast paralleltransported sand from north and south along the shoreface and is resting on fluvial sand.

The combination of cores, GPR and studies of the Recent morphology and depositionalprocesses is a powerful tool to identify palaeo-sedimentary environments (Johannessen et al.,2008). On GPR sections from the central part of the island a series of beach ridges, up to 2.5 mhigh, often with swales in between are underlying the modern aeolian dune sands. Washoverfans, up to 2.5 m thick, are often seen in the GPR sections immediately east of the beach ridgesand can be followed c. 250 m eastwards and may have steep slipfaces. Shoreface sands may befollowed eastward to beach ridges and show westward progradation. Swash bars areoccasionally seen on the shoreface close to the beach ridges. In the northernmost area of theisland the GPR sections are dominated by co-sets with westerly and easterly dipping foresets,indicating bipolar current directions (Møller et al., 2008). These sediments were probablydeposited in a deep, broad tidal inlet north of the initial barrier island similar to what is observed atthe island today.

Facies analysis on the cores and correlations between wells show that barrier islandsediments and related shoreface sand and lagoonal sediments are up to 20 m thick and overlieWeichselian fluvial sand. The first 5000 years the barrier island aggraded and the last 3000 yearsit prograded despite the relative rising sea level rise of c. 15 m during the last c. 8000 years. Thisshows, that if there is a surplus of sand in a tidal area, barrier islands may aggrade even if thereis a rise in sea level. If the rate of sea level rise decreases then the barrier island may prograd.

With this unique dataset with extremely large amounts of OSL datings from core sedimentsit has been possible to construct detailed palaeogeographic maps of the barrier islanddevelopment through time.

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Orthophoto of the Rømø barrier island. The location of Ground Penetrating Radar reflection profiles andseven core wells are shown. Very wide tidal sand flat characterise the north-western and south-western

parts of Rømø.

Johannessen, P.N., Nielsen, L.H., Nielsen, L., Møller, I., Pejrup. M., Andersen, J.T., Korshøj, J.S., Larsen,B. and Piasecki, S. (2008) Sedimentary facies and architecture of the Holocene to Recent Rømø barrierisland in the Danish Wadden Sea. Geological Survey of Denmark and Greenland Bulletin, 15, 49-52. Møller, I., Nielsen, L., Johannessen, P.N., Nielsen, L.H., Pejrup, M., Andersen, T.J., and Korshøj, J.S.(2008) Creating the framework of sedimentary architecture of a barrier island in the Danish Wadden Sea.Proceedings of 12th International Conference on Ground Penetrating Radar, Birmingham, UK, 8 pp.Nielsen, L., Møller, I., Nielsen, L.H., Johannessen, P.N., Pejrup, M., Korshøj, J.S. and Andersen, T.J.(2009) Integrating ground-penetrating radar and borehole data from a Wadden Sea barrier island. Journalof Applied Geophysics, 68, 47-59.

70


TIDAL RAVINEMENT SURFACE IN A TIDE-DOMINATED ESTUARY: PLEISTOCENENHA BE ESTUARY, SOUTHERN VIETNAM

Toshiyuki KITAZAWA

FACULTY OF GEO-ENVIRONMENTAL SCIENCE, RISSHO UNIVERSITY, 1700 Magechi, 360-0194,Kumagaya, Saitama Pref., Japan, [email protected]

The features of tidal ravinement surface (TRS: Allen, 1991; Allen and Posamentier, 1993) inmacrotidal tide-dominated estuary are discussed based on ancient deposits. TRS is an importantsequence stratigraphic boundary in an incised-valley system, because a TRS is developed onlyinside of an incised valley and is not on interfluves (Zaitlin et al., 1994) in contrast to a waveravinements surface. A TRS is created in a transgressive tide-dominated estuary byamalgamation of channel scours as a result of the landward migration of the tidal channelsseparating tidal sand bars (Dalrymple et al., 1992). The sedimentological feature and distributionof TRS formed in a tide-dominated estuary have not been known well because only a fewexamples have been descried. Although TRSs are observed in numerous incised-valley systems,the term TRS is commonly used for amalgamated truncations at the base of tidal inlet channelscutting a barrier island and at the base of flood tidal delta in wave-dominated or wave- andtide-dominated estuaries.

The solid subject in this study is the Middle to Upper Pleistocene Ba Mieu and Thu DucFormations exposed around the Nha Be River, southern Vietnam. The Ba Mieu Formation wasdeposited during marine isotope stage (MIS) 7 to 6, and the Thu Duc Formation was depositedduring MIS 5 (Kitazawa et al., 2006). The formations are deposited in tide-dominatedincised-valley systems consists of estuary and delta (Kitazawa and Tateishi, 2005; Kitazawa,2007). TRS in the formations is divided into 3 types based on the environment.

1) Intertidal-TRS is formed by landward migration of meandering tidal channels in intertidalzone around the bay head. The tidal channels are filled with mud clasts fed from the channelbank. Intertidal-TRS is not laterally continuous relative to incised-valley bottom and the otherTRSs because the tidal channels are small and sometimes abandoned.

2) Bar-channel-TRS is formed by landward migration of braided tidal channels in a marinesand body consists of tidal sand bars and sand flat around the central portion of the estuary. Thechannels filled with sand and gravel are amalgamated with each other and continuous laterally.The continuity depends on the extent and migrating distance of the marine sand body.

3) Subtidal-TRS is formed by landward migration of major subtidal channels. It erodesaway former existing transgressive deposits, and gravel and mud clasts are only preserved as lagdeposits. The continuity depends on the extent and migration distance of the subtidal erosionalzone.

At inland portion, fluvial and salt marsh deposits overlie the basement rocks, andintertidal-TRS is only scattered in tidal flat deposits. In more seaward portion, sand flat and mixedflat deposits are interfingered, that is the landward limit of the bar-channel-TRS at the maximumflooding period. Bar-channel-TRS and subtidal-TRS are amalgamated with each other andremarkable on outcrops. This amalgamated TRS is laterally continuous (at least 15 km),therefore, it is recognized as an important sequence stratigraphic boundarie regionally developedwithin the tide-dominated estuary. The transgressive deposits below the bar-channel TRS thinseaward because of the tidal erosion during later transgression, and are almost eroded away inthe most seaward portion. As a result, bar-channel-TRS and subtidal-TRS commonly erode theunderlying depositional sequence or basement rocks and is recognized as a sequence boundary.In other words, an incised valley formed by fluvial erosion during a lowstand period is againeroded and deepen by tidal channels during the transgression.

The relative extent of TRS to the estuary length is wide in the Pleistocene tide-dominatedNha Be Estuary in comparison to wave- and tide-dominated Gironde Estuary. It is caused by therelative extent of tidal scour, that is, the existence of marine sand body and subtidal erosionalzone.

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Classification of TRS in a tide-dominated estuary section.

Allen, G.P., 1991. Sedimentary processes and facies in the Gironde estuary: a recent model for macrotidalestuarine systems. In: Smith, D.G., Reinson, G.E., Zaitlin, B.A., Rahmani, R.A. (Eds.), Clastic TidalSedimentology. Canadian Society of Petroleum Geologists, Memoir 16, pp. 29–400. Allen, G.P., Posamentier, H.W., 1993. Sequence stratigraphy and facies model of an incised valley fill: theGironde Estuary, France. Journal of Sedimentary Petrology 63, 378–391. Dalrymple, R.W., Zaitlin, B.A., Boyd, R., 1992. Estuarine facies models: conceptual basis and stratigraphicimplications. Journal of Sedimentary Petrology 62, 1130–1146. Kitazawa, T., 2007. Pleistocene macrotidal tide-dominated estuary–delta succession, along the Dong NaiRiver, southern Vietnam. Sedimentary Geology 194, 115–140.Kitazawa, T., Nakagawa, T., Hashimoto, T., Tateishi, M., 2006. Stratigraphy and optically stimulatedluminescence (OSL) dating of a Quaternary sequence along the Dong Nai River, southern Vietnam. Journalof Asian Earth Sciences 27, 788–804.Kitazawa, T., Tateishi, M., 2005. Geometry and preservation process of tidal sand bar deposits of MiddlePleistocene macrotidal tide-dominated delta succession, southern Vietnam. Journal of SedimentologicalSociety of Japan 61, 27–38.Zaitlin, B.A., Dalrymple, R.W., Boyd, R., 1994. The stratigraphic organization of incised-valley systemsassociated with relative sea-level change. In: Dalrymple, R.W., Boyd, R., Zaitlin, B.A. (Eds.), Incised-valleySystems: Origin and Sedimentary Sequences, SEPM Special Publication 51, pp. 45–60.

72


TIDAL DELTAS IN THE LAJAS AND TILJE FORMATIONS: TIDE-DOMINATED ORTIDE-INFLUENCED?

Colleen KURCINKA*, Aitor ICHASO**, Robert W. DALRYMPLE*

*DEPT. GEOL. SCI. & GEOL. ENG., Queen'S University, K7L 3N6, Kingston, Ontario, Canada,[email protected], [email protected]**SHELL CANADA LTD., 400 - 4th ave sw, T2P 2H5, Calgary, Alberta, Canada, [email protected]

The Lower Lajas Formation (Jurassic) located in the Neuquen Basin of western Argentina isthought to represent a deltaic system that accumulated in a back-arc basin (post-rift) (Howell etal., 2005). The funnel-shaped geometry of the basin accentuated the tidal currents whilerestricting wave influence. The basal portion of the Lajas Formation records tide-dominateddeltaic deposits, which grade into a tide-dominated coastline, and eventually into the overlyingfluvial and floodplain deposits of the Challaco Formation (McIlroy et al., 2005). The broadlytime-equivalent Tilje Formation (Jurassic, offshore Norway) also consists of stacked tidallyinfluenced deltaic deposits that accumulated in a rift-basin setting. Both successions have beeninterpreted as tide-dominated by previous workers (Martinius et al., 2001; McIlroy et al., 2005).

Tide-dominated deltas are poorly known relative to other delta types. The moderntide-dominated deltas that have been studied in some detail (e.g.. the Amazon and Fly riverdeltas) are large and mud dominated, while many of the ancient analogues tend to be sandy andon a much smaller scale (e.g.. the Frewens Sandstone). Recent work has suggested that suchsandy tide-dominated deltas may contain abundant oppositely dipping crossbeds, sigmoidalcross-bedding, reactivation surfaces, abundant heterolithic facies, tidal bundles, and doubledrapes as their more distinctive characteristics (Willis, 2005), whereas tidal rhythmites and fluidmuds are widespread in modern muddy deltas. In much new work on coastal systems, there is agrowing realization, however, that reliance on end-member models can be misleading, as mostareas experience an interplay of two or more depositional processes. Thus, it is relevant to askwhat the deposits of a tide-influenced delta are like and how they might differ from those of atide-dominated system. Presumably, tidal features will be present, but they are likely to be mixedwith wave- and/or river-generated structures. Tanavsuu-Milkeviciene and Plink-Bjorklund (2009),for example, have suggested that the presence of fluvial deposits in the delta plain is an indicatorof tidal influence rather than tidal dominance. However, the range of possible mixed-energy deltasis large and there are very few examples in the ancient that can be used for comparison.

Recent work (Ichaso, 2012) on the Tilje Formation in offshore Norway (for which the LajasFormation has been used as an outcrop analog) suggests that these deltaic deposits contain asignificant and pervasive indication of fluvial influence. Evidence of seasonal variations in riverdischarge is present in the heterolithic, mouth-bar and delta-front areas, in the form ofdecimeter-scale variations in the grain size, abundance of fluid-mud layers and the intensity ofbioturbation. Wave-generated structures are only rarely present in progradational successions,but are more common in areas away from the active distributaries and during times of delta-lobeabandonment. This assemblage of structures indicates that this system was formed by amixed-energy delta that would plot approximately half-way between the tide- and river-dominatedend-members on the “delta triangle”, rather than at the tide-dominated apex. Preliminaryinvestigations of the Lajas Formation deltas (Figure 1) suggest that tidal action might also havebeen over-estimated in this system, and that river influence may be significant. While organicdrapes, some of them double, are present in the toesets of some dunes, they are not ubiquitous.Other compelling tidal indicators are absent or sparse, and paleocurrent data indicate primarilyseaward-directed crossbeds. Similarities exist between the Lajas Formation and thetide-influenced Frewens Sandstone, as the Frewens is also strongly ebb-dominated. However,the Frewens Sandstone contains widespread tidal indicators in the form of true double muddrapes, heterolithic deposits, and local current reversals (Willis, 1999). It can be suggested thatthe Lajas Formation, much like the Tilje Formation, is a mixed tide-river delta and its position onthe deltaic triangle should also be moved. More work is needed on both modern and ancienttide-dominated and mixed-energy deltas in order to determine the expected range of deposittypes in mouth-bar and delta-front settings.

Howell, J.A., Schwarz, E., Spalletti, L.A., and Viega, G.D. 2005. The Neuquen Basin: an overview.In:Spalletti, L., Veiga, G., Howell, J.A. & Schwarz, E. (eds.), The Neuquén Basin: A Case Study in SequenceStratigraphy and Basin Dynamics. Geological Society, London, Special Publications.

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Ichaso, A. 2012. Spatial and temporal controls on the development of heterolithic, lower Jurassic tidaldeposits (upper Are and Tilje Formations), Haltenbanken area, offshore Norway. Unpublished Ph.D thesis,Queen’s University, p. 252.Martinius, A.W., Kaas, I., Næss, A., Helgesen, G., Kjærefjord, J.M., and Leith, D.A. 2001. Sedimentology ofthe heterolithic and tide-dominated Tilje Formation (Early Jurassic, Halten Terrace, offshore mid-Norway).In: Martinsen, O.J. and Dreyer, T. (eds.), Sedimentary environments offshore Norway – Paleozoic to recent(Eds), Norwegian Petroleum Foundation Spec. Publ. 10, 103-144.McIlroy, D., Flint, S.S., Howell, J.A. & Timms, N.E. 2005. Sedimentology of the tide-dominated LajasFormation, Jurassic Neuquén Basin, Argentina. In: Spalletti, L., Veiga, G., Howell, J.A. & Schwarz, E.(eds.), The Neuquén Basin: A Case Study in Sequence Stratigraphy and Basin Dynamics. GeologicalSociety, London, Special Publications.Tanavsuu-Milkeviciene, K., and Plink-Bjorklund, P. 2009. Recognizing tide-dominated versustide-influenced deltas: the Middle Devonian strata of the Baltic Basin. Sedimentology 79, 887-905. Willis, B.J., 1999. Architecture of the tide-influenced river delta in the Frontier Formation of centralWyoming, USA. Sedimentology 46, 667-688.Willis, B.J., 2005, Deposits of tide-influenced river deltas. In: Giosan, L., and Bhattacharya, J.P. (eds.),River Deltas—Concepts, Models and Examples. SEPM Special Publication 83, p. 87-129.

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LITTORAL SEDIMENTATION WITHIN SPARTINE AND OBIONE COMMUNITIES INTHE SOMME ESTUARY (EASTERN ENGLISH CHANNEL). PRELIMINARY RESULTS

Sophie LE BOT*, F BERTEL*, Estelle LANGLOIS*, Estelle FOREY*, Antoine MEIRLAND**,Robert LAFITE*

*UMR CNRS 6143 M2C, UNIVERSITE DE ROUEN , Place Emile Blondel, 76821, Mont Saint Aignan,France, [email protected]**GEMEL PICARDIE, 115 Quai Jeanne D’arc, 80230, Saint-Valéry-Sur-somme, France

Like many estuaries in the English Channel, the Somme estuary follows an infill pattern(Tessier et al., 2011). Land reclamation (embankments, polders) increase reinforces the naturalaccretion process (Bastide, 2011). The infilling leads to important modifications of environmentuses (e.g. fisheries, navigation).

The Somme estuary is macrotidal but wave-dominated due to high energy wave conditions.They induce strong littoral drift leading to the development of a gravel barrier at its mouth, on thesouthern part (Anthony and Héquette, 2007; Marion et al., 2009). The tidal regime is semi-diurnaland flood-dominated. The tidal range reaches 9-10 m in spring conditions. Fluvial discharge of theSomme river is weak (5-60 m3/s) (Dupont et al., 1994), inducing an infilling of the estuary almostexclusively with sands of marine origin (Dupont, 1981) and bioclasts from endemic benthicproduction (Desprez et al., 1998).

Sedimentation rate in the Somme estuary is about 700 000 m3/yr, corresponding to a meanseabed elevation between 1.3 and 1.8 cm/yr (Verger, 2005; Bastide, 2011). These rates aresimilar to those recorded in the Authie estuary located some tens of kilometers to the North(0.71-1.6 cm/yr; Marion, 2007). Vegetation plays a major role in the estuarine sedimentation,since it constitutes an hydrodynamic barrier that favours sediment deposition. In particular,Spartina townsendii and Halimione portulacoides communities play a significant effect onsedimentation rate. These species are respectively observed on the low marsh (between slikkeand schorre) flooded by mean tides and on the mid-marsh flooded by spring tides. In Europeansalt marshes, sedimentation rates are in the range of 15 cm/yr in pioneer zones with Spartina and4.7 cm/yr in mid salt marsh vegetation with Halimione (Ranwell, 1964; Brown et al., 1998;Langlois et al., 2001).

In order to analyze sediment characteristics in Spartina and Halimione communities, shortcores (30-40 cm) have been collected on three sites of the estuary selected as representative ofdifferent hydro-sedimentary conditions (exposed and sheltered sites). Three replicates have beensampled per site. A visual description of the cores has been realised to determine sedimentlayering and layer thicknesses (Figure 1). Grain-size analyses have been conducted onsub-samples in specific core layers. Topographic surveys, carried out using an airborne scanningLIDAR from the CLAREC team and a high resolution laser electronic station, have been used toassess the erosive or accumulative sedimentary trend through the winter 2011-2012.

A grain-size varibility is observed at different scales: the vegetation communities scale, theestuary scale (inter-site variability) and the replicate scale (intra-site variability). Spartina.communities are associated with a sandy dominant sedimentation (122 and 185 mm), whereasHalimione communities are merely silty dominated (38 and 84 mm; Figure 1) under the influenceof decantation processes. This may be explained by differences in exposure of the communitiesto the main marine forcing agents, mainly controlled by altitude, that influences tidal immersiontime, position along the cross-shore profile and vegetation density, both controlling the energydissipation of the forcing agents. In the estuary, a grain size fining trend is observed from sitesopen on the marine environment to sheltered sites, due to various exposure degrees to tide andwave action. The three study sites belong to different estuarian sub-units, defined by Dupont(1981) as variously influenced by actions of the forcing agents.Site-effect is therefore important asconfirmed by the contrasted topographic evolution recorded during winter 2011-2012. Within asite, sedimentary record is homogeneous exception made of the number and depth of layers.

Rythmicity is observed in core sedimentation, due to the repetition of a two-layer pattern. InHalimione communities, the two-layer pattern (0.7-5.8 cm) is composed of one dark layer (0.3-1cm), often rich in stems, and one clear silty layer (0.4-4.7 cm). Stem-rich dark layers may indicatethe period of the falling leaves of Halimione. The two-layer pattern would therefore representannual sedimentation, what is consistant with mean annual sedimentation rates previouslyrecorded (Verger, 2005; Marion, 2007; Bastide, 2011). In Spartina communities, the the two-layerpattern displays various compositions and thicknesses. They are composed of: (i) one layer(0.75-9 cm) made of fine sands and one layer (0.4-3.4 cm) made of very fine sands, (ii) two0.75-cm layers, dark or light, made of very fine sands, or (iii) one sandy layer (2.8-11.4 cm)alternating with a shelly layer (0.9-1.4 cm). Compared to the mid-marsh where Halimione is

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observed, the stronger sedimentation variability in Spartina community is probably to relate to ahigher variability of the hydrodynamic conditions due to: (i) a stronger exposure degree of thelow-marsh where Spartina is observed, (ii) a variability in exposure degree according to thelocation of the site within the Somme estuary, and/or (iii) the vegetation cover (dense in the caseof Halimione, scarse in the case of Spartina).

Core sampled in the Halimione community (core 0Z1A). From left to right : photo, scheme, sub-samples,visual description. The colour of sub-samples inform on their grain-size: mode of 38, 84 and 96-116 mm

respectively for orange, red and brown colours.

Anthony and Héquette, Sediment. Geol. (2007)Bastide, PhD Thesis (2011)Brown et al., Mar. Poll. Bull. (1998)Desprez et al., in Auger et al. (Ed.) (1998)Dupont, PhD Thesis (1981)Dupont et al., Mar. Geol. (1994)Langlois et al., Journ. Veget. Science (2001)Marion, PhD thesis (2007)Marion et al., Estuar. Coast. Shelf Science (2009)Ranwelle, Journ. Ecology (1964)Tessier et al., Sediment. Geol (2011)Verger, Belin Ed. (2005)

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FACIES MODEL OF A FINE-GRAINED, TIDE-DOMINATED DELTA: LOWER DIR ABULIFA MEMBER (EOCENE), WESTERN DESERT, EGYPT

Berit LEGLER*, Howard JOHNSON**, Gary HAMPSON**, Benoit MASSART**, ChristopherJACKSON**, Matthew JACKSON**, Ahmed EL-BARKOOKY***, Rodmar RAVNAS****

*UNIVERSITY OF MANCHESTER, SEAES, Oxford Road, Williamson Building, M9 13PL, Manchester, Uk,[email protected]**IMPERIAL COLLEGE LONDON, Prince Consort Road, SW2 7AZ, London, Uk***SHELL EGYPT, El-Horreya, 2681, Cairo, Egypt****NORSKE SHELL, Tankvegen 1, 4056, Tananger, Norway

Existing facies models of tide-dominated deltas largely omit fine-grained, mud-rich deltaicsuccessions. Sedimentary facies and sequence stratigraphic analysis of the Late Eocene Dir AbuLifa Member (Western Desert, Egypt) aims to bridge this gap. The succession was deposited in astructurally controlled, shallow, macrotidal embayment and deposition was supplemented byfluvial processes but lacked wave influence.

The Dir Abu Lifa Member, studied along a 12 km-long, continuously exposed cliff facethrough an exceptionally well-preserved succession of tidal deposits containing a plethora of tidalindicators (c. 80 m thick and divided into seven facies associations: FA1-7). The majority of thesuccession (FA1-6) was deposited in a tide-dominated environment, which was supplemented byfluvial processes but lacked wave influence. Two main genetic units are identified: (1)non-channelised tidal bars (FA1-2); and (2) tidal channels (FA3-6). The non-channelised tidalbars comprise coarsening upwards parasequences (c. 4-12 m thick), which passed upwards fromshallow, brackish water mud-dominated bays (c. 5-15 m water depth) and into sandy heterolithictidal bar forms, including large, forward-facing accretion surfaces, sometimes with evidence ofemergence at the top (rooted with thin coals). The tidal channels are preserved as both single-and multi-storey bodies, but displaying different types of bar and infill: (1) FA3 channels werefilled by laterally migrating, elongate tidal bars (with Inclined Heterolithic Strata - IHS; c. 5-25 mthick), (2) FA4 channels were filled by large, forward-facing sigmoidal bars (with SigmoidalHeterolithic Strata - SHS; up to 10 m thick), (3) FA5 channels were filled by side bars displayingoblique to vertical accretion (c. 4-7 m thick), and (4) FA6 channels were filled byvertically-accreting mud (c. 1-4 m thick). Palaeocurrent data, supported by a wide range of othertidal indicators, shows that these channels were swept by bidirectional tidal currents and weretypically mutually evasive (the dominant westerly currents were fluvial/ebb-tide oriented and thesubordinate easterly currents were flood oriented).

Larger scale, stratigraphic relationships show that the lower Dir Abu Lifa Member comprisesthree stacked, progradational parasequence sets bounded by carbonate-cemented transgressivelags (FA7), which are overlain by regionally extensive ravinement surfaces. Significantalong-strike variability defines three distinctive facies belts (SW, Central and NE). The SW andNE facies belts are fine grained, mud-rich and dominated by non-channelised tidal bars (FA1-2),smaller channelised bodies (FA5) and mud-filled channels (FA6). The central belt is dominated bylarge, multilateral and multi-storey channel sandstones with widespread IHS and occasional SHS(FA3-4) within both PSS1 and PSS2 and is interpreted as a major tidal-distributary channel belt.These areas preserve tidal bars and intercalated tidal distributary channels deposited in a deltafront to inter-tidal to supra-tidal lower delta plain setting.

A tide-dominated delta model is favoured, based on: (1) the gross stratigraphy (LateEocene to Oligocene) forms part of a large-scale regressive succession, which passes fromoffshore shallow marine sandstones, through inshore/tidal sandstones and mudstones (includingthe Dir Abu Lifa Member), and into fluvial deposits; (2) the parasequences and parasequence setstacking patterns are characterised by overall progradational patterns; (3) there is an absence ofboth depositional transgressive successions and tidal ravinement surfaces; and (4) architecturalrelationships demonstrate contemporaneous tidal distributary channel infill and tidal bar accretionat the delta front.

The data-driven interpretation of an exclusively tide-dominated delta significantly expandsthe range of facies and sequence stratigraphic models available for the analysis of ancient tidalsuccessions, which are currently biased towards transgressive, valley-confined estuaries.

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Generalised facies model of the Dir Abu Lifa Member

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RHYTHMITES PRESERVATION IN MACROTIDAL ESTUARINE ENVIRONMENTS:FROM UPSTREAM TO DOWNSTREAM ESTUARY

Maxence LEMOINE*, Julien DELOFFRE*, Robert LAFITE*, Sandric LESOURD**, PatrickLESUEUR***, Antoine CUVILLIEZ****, Nicolas FRITIER*, Nicolas MASSEI*

*UMR CNRS 6143 M2C, UNIVERSITE DE ROUEN , Place Emile Blondel, 76821, Mont Saint Aignan,France, [email protected]**UMR 8187 LOG, 28 Avenue Foch, bp 80, 62930, Wimereux, France***UMR CNRS 6143 M2C, UNIVERSITE DE CAEN, 24 rue des Tilleuls, 14000, Caen, France****UMR 6294 CNRS LOMC, 53, rue Prony, bp 540, 76058, Le Havre, France

Estuaries are interface environments between continental and marine domains. Theestuarine system classifications allow estuarine zonation based on the longitudinal distribution ofhydrodynamic forcing relative energies (flow, tide and swell) which contribute to thehydrodynamics and sediment dynamics. The respective influence of hydrodynamic processeswas represented by Dalrymple et al., 1992 (Fig. 1). The resulting hydrodynamics is highly variableand nonlinear in space but also in time: from seconds (swell) to multi-year (interannual variabilityof hydrological flows).

The Seine estuary is a macrotidal estuary (tidal range of 8m at the mouth) developed over160km up the upstream limit of tidal wave penetration at the Poses dam. With an average riverflow of 450m3.s-1 (ranges between 200 and 2200), the Suspended Particles Matter (SPM) annualflux is about 700,000tons, with 80% of solid discharge during the flood period (Avoine, 1986). Inthe downstream part, the Seine estuary Turbidity Maximum (TM) is the second SPM stock with atonnage rangin from 300,000 to 500,000tons (Avoine et al., 1981). During their transfer to theEnglish Channel, the fine particles can be trapped in (i) the intertidal mudflats, preferential areascharacterized by low hydrodynamics and generally sheltered of the flow, the main tidal current theSeine river and (ii) the TM. The Seine estuary is a strongly man-altered estuary with numerousfacilities in order to secure navigation. One consequence of these developments is the tidal boredisappearance.

In the upstream part, sedimentation occurs during the flood (flow > 800m3.s-1) with ahigher mean water level causing permanent dewatering of the mudflats and the SPM settling. Thesedimentation episode intensity depends on the flood intensity (pluri-centimetric during strongfloods carrying larger quantities of SPM) (Guézennec et al., 1999). The gradual release ofparticles filed during the flood is mainly provided by tidal cycles during low flow periods (Deloffreet al., 2005). Finally, at the annual scale, the intertidal mudflats of this area seem close tobalance. The rhythmites are not or poorly preserved on the lateral areas of the upper estuary,except in connected basins with the river Seine (i.e. docks), and developed sheltered area fromthe currents, where sedimentation and recording are almost continuously for several decades.

Close to the mouth, the tidal influence in the deposit rhythms increases with abruptperiods of TM particles settling (centimeter to pluricentimeters per tide) preferentially during lowwater (TM not expelled by the Seine river) and during the largest spring tides (Lesourd et al.,2003 ; Deloffre et al., 2006). The particles settled come from the TM. During the rest of the year, atendency to erosion is recorded (in winter and in flood) following (i) tidal cycles (progressiveerosion) and (ii) storm surges (erosion-time) (Le Hir et al., 2001). Just as in the upper estuary, thesedimentary evolution of the stock shows some stability indicating a lack of preservation ofrhythmites on an annual basis (Deloffre et al., 2006).

The Seine estuary middle part is not an intermediate between the upstream and thedownstream behaviors. This area is strongly influenced by the flow and the inter-annual climaticcyclicity (6-7 years) (Massei et al., 2009). Plurimetric sedimentation occurs during low floods. Themudflat nourishment lasts during one to two years before reaching its size equilibrium, whichallows the rhythmites preservation. Erosion is sudden and intense and it occurs during strongfloods, removing the sedimentary stock and therefore not allowing conservation "long term" ofthese rhythmites.

Although macrotidal estuarine environments are potentially suitable for sedimentaryrecords of tidal cycles, their preservation is the Seine estuary is strongly limited by stronghydrodynamic variability and paroxysmal events. This strong variability is expressed at differenttime scales: (i) event (swell), (ii) daily / monthly (tidal cycles) or (iii) annual / pluri-annual

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(hydrologic variability). Anthropism (dikes, filling) promotes the increase in hydrodynamic, with achannel current velocities increase. These changes are responsible for a shift of the TMdownstream and the muddy intertidal muddy surface reduction (Cuvilliez et al., 2009). It appearsthat sedimentation occurs during exceptionnal condition periods (flood, spring tides…) and in theactual hydrological conditions, erosion seems to be the normal behavior. Finally, in this macrotidalestuary, although sedimentation events are consistent (pluricentimetric) over short periods, thepreservation rate of rhythmites is relatively low. Only a few areas in connection with the Seineriver (docks) are likely to present a continuous sedimentation record in macrotidal estuary.

energy distribution in a tide-dominated estuary (Dalrymple et al., 1992) and studied sites location

Avoine, J., 1986. Evaluation des apports fluviatiles dans l’estuaire de la Seine. In Ifremer, editor, La baie deSeine (GRECO Manche) : Caen, Ifremer, 117-124.Avoine, J., Allen, G.P., Nichols, M., Salomon, J.C., Larsonneur, C., 1981. Suspended sediment transport inthe Seine estuary, France: effect of man-made modifications on estuary-shelf. Sedimentology. MarineGeology, 40, 119–137.Cuvilliez, A., Deloffre, J., Lafite, R., Bessineton, C., 2009. Morphological responses of an estuarine mudflatto constructions since 1978 to 2005 : The Seine estuary (France). Geomorphology, 104, (3-4), 165-174.Dalrymple, R.W., Zaitlin, B.A., Boyd, R., 1992. Estuarine facies models: conceptual and stratigraphicimplications BASIS. Journal of Sedimentary Petrology, 62, (6), 1130-1146.Deloffre, J., Lafite, R., Lesueur, P., Lesourd, S., Verney, R., Guézennec, L., 2005. Sedimentary processeson an intertidal mudflat in the upper macrotidal Seine estuary, France. Estuarine, Coastal and ShelfScience, 64, (4), 710-720.Deloffre, J., Lafite, R., Lesueur, P., Verney, R., Lesourd, S., Cuvilliez, A., Taylor, J., 2006. Controllingfactors of rhythmic sedimentation processes on an intertidal estuarine mudflat – Role of the turbiditymaximum in the macrotidal Seine estuary, France. Marine Geology, 235, (1-4), 151-164.Guézennec, L., Lafite, R., Dupont, J.P., Meyer, R., Boust, D., 1999. Hydrodynamics of suspendedparticulate matter in the freshwater zone of a macrotidal estuary (the Seine estuary, france). Estuaries, 22,(3A), 717-727.Le Hir, P., Ficht, A., Jacinto, R., Lesueur, P., Dupont, J.P., Lafite, R., Brenon, I., Thouvenin, B., Cugier, P.,2001. Fine sediment transport and accumulations at the mouth of the seine estuary (France). Estuaries andCoasts, 24, (6), 950-963.Lesourd, S., Lesueur, P., Brun-Cottan, J.C., Garnaud, S., Poupinet, N., 2003. Seasonal variations in thecharacteristics of superficial sediments in a macrotidal estuary (the Seine inlet, France). Estuarine, Coastaland Shelf Science, 58, (1), 3-16.Massei, N., Laignel, B., Deloffre, J., Mesquita, J., Motelay-Massei, A., Lafite, R., Durand, A., 2009.Long-term hydrological changes of the Seine River flow (France) And their relation to North AtlanticOscillation over the period 1950-2008. International Journal of Climatology, 30, (14), 2146-2154.Verney, R., Deloffre, J., Brun-Cottan, J.C., Lafite, R., 2007. The effect of wave-induced turbulence onintertidal mudflats : Impact of boat traffic and wind. Continental Shelf Research, 27, (5), 594-612.

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SEDIMENT TRANSPORT PATTERNS AND SOURCES IN A RIVER DELTA-TIDALFLAT COMPLEX IN TAIWAN

James T. LIU, Wayne, C. CHEN

INSTITUTE OF MARINE GEOLOGY AND CHEMISTRY, NATIONAL SUN YAT-SEN UNIVERSITY, 70Lien-Hai rd., 80424, Kaohsiung, Taiwan, roc, [email protected], [email protected]

Zhoushuei River has the largest sediment discharge (50-60 Mt) on the west coast inTaiwan. Its mouth is located on a mesotidal (tidal range between 2 and 4 m) coast. Because ofthe strong tidal currents and seasonal monsoon waves in the Taiwan Strait, the sedimentexported by the river formed a small fan-shaped tidal delta and a large tidal depositional systemlocated immediately north of the river mouth. This tidal system contains tidal ridges separated bylarge tidal channels. Swathbars separated by cross-bar channels are large secondarydepositional features more or less perpendicular to the main tidal channel. Geomorphologically,the delta at the river mouth and the tidal flat seem to be one complex system.

It is hypothesized that this system is the immediate/temporary sink of sediment exported bythe river though plume-tide interaction. The sediment might be transported out of the tidal systemduring ebbing tide into the littoral drift and further dispersed by alongshore currents andtidal/coastal current systems.

To test the hypothesis surfacial sediment samples from the river delta and the tidal flatcomplex were taken in May (the end of dry season) and September (end of the flood season)2010. The samples were analyzed for the grain-size composition of the original (Liu et al., 2002),the lithogenic and non-lithogenic fractions of the samples (Liu et al., 2009). Six grain-sizesclasses were used in the analysis, including clay, silt, very fine sand, fine sand, medium sand,and coarse sand. The samples were also analyzed for their organic (TOC, TN) content and C/Nratio. Statistics-based trend analysis techniques (McLaren Model and Transport Vector) and themulti-vairate EOF analysis technique combined with ‘digital filters’ were used to decipher theinformation contained in the spatial grain-size distribution patterns (Liu et al, 2000, 2002).

According to the McLaren Model, sediment transport directions in the study area are shownin Figure 1a for the dry season data set and Figure 1b for the wet season data set. Commonthemes in these two scenarios are the bi-directional transport along the surf zone on the outeredge of the complex, which is due to the tidal currents and seasonal littoral drift. In the dryseason, the influence of the river is weak, and on the side-lobes of the delta the sedimenttransport patterns are bi-directional (landward and seaward) due the influence of the river effluentand tide (Fig. 1a). The sediment mainly moves from the river delta to the tidal flat (Fig. 1a).

In the more energetic wet season where the water level is higher over the complex,bi-directional transport exists along the main tidal channel and along the upper tidal flat, the netsediment movement is still from the river into the tidal flat (Fig. 1b). Over the delta, due theincreased river influence, the sediment transport patters are seaward except on the south side ofthe delta where secondary flood transport exists (Fig. 1b).

Results from filtering and EOF technique show among the possible forcings of riverdischarge, tidal transport, wave sorting, and littoral drift, none of them is the dominantfactor/forcing that influenced the spatial grain-size patterns observed in the dry season. In the wetseason, the northbound littoral drift appears to be the dominant factor/forcing. This is becausethe incident monsoon waves are from the SW in the summer. Other forcings are of secondaryimportance. Despite of the large sediment load in the summer, most sediment discharged by theriver bypasses the delta-tidal flat complex and is transported further away from the study area. However, the river is the primary source for organic material in the complex. Through grain-sizeaffinity, sediment that is organic-rich and has stronger terrestrial signals (high C/N) is associatedmostly with the distribution of clay in the upper tidal flat and river delta in both seasons.

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Sediment trend analysis results according to the McLaren Model for (a) the dry season and (b) wet season. The lengths and widths of the arrows have no magnitude implication. They merely indicate statistically

valid transport directions. The black stars indicate the sampling locations.

Liu, J.T., Huang, J.-S., and Chyan, J.-M., 2000. The coastal depositional system of a small mountainousriver: a perspective from grain-size distributions. Marine Geology, 165 (1-4), 63-86.Liu, J.T., Liu, K.-j., and Huang, J.-S., 2002. The influence of a submarine canyon on river sedimentdispersal and inner shelf sediment movements: a perspective from grain-size distributions. MarineGeology, 181 (4), 357-386.Liu, J.T., Hung, J.-J., and Huang, Y.-W., 2009. Partition of suspended and riverbed sediments related tothe salt-wedge in the lower reaches of a small mountainous river. Marine Geology, 264, 152-164.

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TIDAL FACIES IN SILICICLASTIC, CARBONATE AND MIXED MICROTIDALANCIENT SYSTEMS OF SOUTHERN ITALY

Sergio LONGHITANO*, Domenico CHIARELLA**, Luigi SPALLUTO***

*UNIVERSITY OF BASILICATA, DEPARTMENT OF GEOLOGICAL SCIENCES, Via Dell'Ateneo Lucano,10, 85100, Potenza, Italy, [email protected]**WEATHERFORD PETROLEUM CONSULTANTS AS, Folke Bernardottevei, 5007, Bergen, Norway***UNIVERSITY OF BARI DIPARTIMENTO DI SCIENZE DELLA TERRA E GEOAMBIENTALI, ViaOrabona, 4, 70100, Bari, Italy

Tidalites are usually associated to meso-, macro- or mega-tidal oceanographic settings,where the tidal excursions are the main hydrodynamics in sediment distribution and organizationalong coastal environments (Longhitano et al., 2012a). However, also in microtidal settings (i.e.,the Italian coastlines) tides may have influence on to the sediments, when: (i) tidally-drivencurrents are amplified throughout marine straits, as today along the Messina Strait; (ii) whenother, usually dominant, hydrodynamic forces (i.e., waves or currents) are mitigated in theirstrength by coastal embayments, as in the Lagoon of Venice, or (iii) along barred coasts, wheretidal waves enter bays isolated from the open sea by discontinuous sandy bars, as in thepresent-day Lagoon of Lesina. Tidal influence/dominance along microtidal coasts occurred alsoduring the Mesozoic and the Cenozoic in a variety of ancient environments, presently croppingout in south Italy.

Examples of ancient tidally-dominated/-influenced facies developed under microtidalconditions are widely detectable across southern Italy (Longhitano et al., 2012b). Tidalites weredocumented in: (i) terrigenous, siliciclastic-rich sandstones, (ii) carbonate, platform-like limestonesand (iii) mixed, silici-/bioclastic sandstones. Each of these deposits recorded depositional systemsthat include different facies assemblages with highly varying properties, although the basicprocess was roughly the same.

Three main field examples are proposed from the lower Pleistocene Catanzaro palaeo-strait(Calabria, Fig. 1A) (Longhitano et al., 2012b), the upper Cretaceous Apulian platform (Apulia, Fig.1B) (Spalluto, 2008), and the middle-upper Pliocene Acerenza palaeo-bay (Basilicata, Fig. 1C)(Chiarella et al., 2012).

These case studies summarize the main facies differences and the petrophysical featuresof tidalite-bearing deposits accumulated in very different microtidal scenarios, having afundamental role in reservoir characterisation and fluid migration models.

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Example of tidalites exposed in southern Italy. (A) Lowere Pleistocene dune-bedded siliciclastic sandstonesfrom the Catanzaro Palaeostrait. (B) Upper Cretaceous stromatolitic limestones from the Apulia Platform.

(C) Middle-upper Pliocene mixed, bioclastic/siliciclastic cross-bedded sandstones from the AcerenzaPalaeobay.

Chiarella D., Longhitano S.G., Sabato L., Tropeano M. (2012). Sedimentology and hydrodynamics of mixed(siliciclastic-bioclastic) shallow-marine deposits of Acerenza (Pliocene, Southern Apennines, Italy). Ital. J.Geosci., 131, 136-151.Longhitano S.G. , Mellere D., Steel R.J., Ainsworth B. (2012a). Tidal Depositional systems in the RockRecord: a Review and New Insights. In: Longhitano S.G., Mellere D., Ainsworth B. (Eds.) Modern andancient depositional systems: perspectives, models and signatures, Sed. Geol. Special Issue, in press.Longhitano S.G. , Chiarella D., Di Stefano A., Messina C., Sabato L., Tropeano M. (2012b). Tidalsignatures in Neogene to Quaternary mixed deposits of southern Italy straits and bays. In: Longhitano S.G.,Mellere D., Ainsworth B. (Eds.) Modern and ancient depositional systems: perspectives, models andsignatures, Sed. Geol. Special Issue, in press.Spalluto L. (2008). Sedimentology and high-resolution sequence stratigraphy of a lower Cretaceousshallow-water carbonate succession from the Western Gargano Promontory (Apulia, Southern Italy).GeoActa Spec. Publ. 1, 173-192.

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BENTHIC HABITAT DIVERSITY IN COARSE SEDIMENT UNDER HIGH MACROTIDALENVIRONMENT

Sophie LOZACH*, Romain ABRAHAM**, Alexandrine BAFFREAU*, Jean-Claude DAUVIN*, DenyMALENGROS***, Emmanuel POIZOT****, Alain TRENTESAUX**

*UMR CNRS 6143 M2C, UNIVERSITE DE CAEN, 24 rue des Tilleuls, 14000, Caen, France,[email protected]**UMR CNRS 8217 GEOSYSTEMES, Université Lille1 U.f.r. des Sciences de la Terre, Bâtiment sn5,59655, Villeneuve D'Ascq, France***UMR CNRS 8217 GEOSYSTEMES, Université Lille1 U.f.r. des Sciences de la Terre, Bâtiment sn5,59655, Villeneuve D’ascq, France****GEOCEANO, Cnam/intechmer bp 324, 50110, Tourlaville, France

EUNIS (European Nature Information System) is the habitat typology of reference in Europebut it must be implemented by new observations, particularly for the more detailed levels of theclassification in coarse sediments which were historically less explored because of samplingdifficulties.

Two surveys in 2010 and 2011 permitted to sample twelve rectangular areas in the mid partof the Channel dominated by coarse sediment habitats in a high hydrodynamic environmentstrongly influenced by tidal currents (see Trentesaux et al., this conference for the map). Duringthe survey, four longitudinal side-scan sonar (SSS) profiles were realised (~10 nm length) in eacharea allowing a real time selection of sampling areas. A minimum of four 0.25 m² Hamon grabsampling stations for quantitative macrofaunal and sediment analysis and two video footages(ROV Seabotix LBV200) were selected in each area (see figure). The main objectives of thisstudy were to re-assess the EUNIS typology along an east-west gradient in the English Channel,and to find a way to integrate acoustic information in the description and mapping of the habitatswhich is not yet taken into account.

The sampling protocol provided five descriptors of the benthic environment that haddifferent levels of benthic habitat structure: (i) small scale infauna distribution (grabs), (ii) smallscale epifauna distribution (grabs), (iii) sediment grain size and pictures of collected sediments(grab), (iv) seabed morphology (SSS) and (v) macrofauna and megafauna seascape (ROV). Allthis information will be integrated in the EUNIS habitat typology taking into account mainly thetype sedimentary and benthic macrofauna. This poster presents an approach that follows differentsteps:

- First of all, a coding for side-scan sonar images was developed to incorporate seabedmorphology descriptions. For this, it is distinguished different types of seabed morphology in theobserved acoustic images that has compared with general seabed features previously describedin publications (see Ashley, 1990) to get different ‘types’ of sonar signatures.

- Then, as views of the benthic habitat were obtained at different scales according to thegear used (ROV or grab), the biological data is processed with the different available descriptorsto improve the EUNIS habitats coding.

- The final step was to cross-check EUNIS interpretation with seabed signatures coding andintegrated these descriptions into benthic habitat typology.

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From the left to the right: the side-scan sonar, the Hamon grab and the ROV Seabotix LBV200L. Picturesbelow show examples of raw observation obtain during the survey by these equipments.

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EFFECT OF THE 2011 GIANT TSUNAMI ON A SANDY BEACH AT OARAI, EASTERNJAPAN

Yasuhiko MAKINO*, Shota ARAI**, Takashi ITO**, Futoshi NANAYAMA***

*IBARAKI UNIV., Bunkyou 2-1-1, 310-8512, Mito, Japan, [email protected]**IBARAKI UNIV.,, Bunkyou 2-1-1, 310-8512, Mito, Japan***GSJ/AIST, Higashi, 305-8567, Tsukuba, Japan

Introduction The 2011 Tohoku earthquake (Mw 9.0) occurred in the Japan Trench on March 11 and

caused a giant tsunami, which struck the coasts of countries bordering the Pacific Ocean. Abouttwenty thousand people in eastern Japan were dead or missing as a result of the earthquake andtsunami. The Oarai Sun Beach on the Pacific coast of eastern Japan near Ibaraki University wasstruck by three tsunami waves, the third of which was the highest, at 4.0 m.

We investigated inundation of the sandy beach by the tsunami, the redistribution of sandysediments, and the current system of the 2011 giant tsunami by examination of changes to thetopography of the beach, sedimentary structures developed there, and damage to man-madestructures on and near the sandy beach.

Results1. Remote imagery

We searched the Internet for information about the Oarai area after the tsunami. Satelliteimages and aerial photographs provided information on the area and depth of inundation and onchanges to the beach topography. After the tsunami, new channels had been formed in the widebackshore area of the beach. Before the tsunami, the backshore area was flat and grass covered.The configuration of the channels shows that they were formed by return flows.2. Field work

The information we obtained from the Internet was confirmed during our field work. Weconducted field investigations of the depth of inundation and the thickness of sand deposits alongtwo transect lines (Fig. 1). Line IH was 700 m long and line ON was 1200 m long. Sand depositsalong both lines were in the form of a thin veneer, less than 6 cm thick.

The tsunami current system on Oarai Sun Beach consisted of run-up flows travelling fromS to N and return flows travelling NW to SE.Discussion

The run-up flows appear to have been controlled and redirected by the position of a raisedroad between the residential area and the port area, and the thickness of sand it deposited was athin veneer. The current system indicates that run-up flows were destructive over a very shorttime, but the return flows were mainly within newly cut channels, and exerted traction for a longerperiod of time. Evidence of the strength of the run-up surge is seen in the transport of two steelbridge girders (10 m long) over a distance of 100 m, fishing boats and many shipping containersmoved landward from the port area, bending of steel poles, tilting of thick wooden poles, and thecreation of plunge pools.

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Inundation area at Oarai Sun Beach

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SEDIMENTATION OF THE 2011 GIANT TSUNAMI ON A SANDY BEACH ON THEPACIFIC COAST OF EASTERN JAPAN

Yasuhiko MAKINO

IBARAKI UNIV., Bunkyou 2-1-1, 310-8512, Mito, Japan, [email protected]

Introduction The Pacific coast of the Japanese Islands has been struck by many giant tsunamis over

geological time. Giant tsunamis caused by earthquakes in and around the Japan Trench haveoccurred every several hundred to one thousand years. Very few studies have documented thechanges to sandy beach sediments immediately after such huge tsunamis, given the rarity ofthese events. The 2011 tsunami provided an opportunity to study the effects of a large tsunami ona sandy beach.

The 2011 Tohoku earthquake occurred in the Japan Trench off Sanriku at 14:46 JST onMarch 11. About 30 minutes later, a giant tsunami struck the Pacific coast of eastern Japan,including Oarai Sun Beach at Oarai in Ibaraki Prefecture. Oarai Sun Beach, which is about 1000m wide and extends 500 m inland, was struck by three tsunami waves. The third run-up flow wasat 16:52 JST and, at 4 m, was the highest wave. The topography of the sandy beach waschanged by the tsunami waves, various new sedimentary structures were formed, and man-madestructures were damaged. These changes on the beach provide information about the currentsystems of the tsunami.

Current system Evidence of the direction of flow of the tsunami on the beach was examined during field

surveys and from aerial photographs. The first tsunami wave struck Oarai at 15:20 JST, and thethird wave, at 16:52 JST, was the biggest, with a height of 4.0 m at Oarai port. Run-up flows werefrom S to N, and return flows were from NW to SE.

Evidence of the tsunami on the beach Run-up flows

Directional features and other evidence of the passage of the run-up flows indicate asurge of great strength.1. Two very heavy steel bridge girders (10 m long) were carried about 100 m inland.

2. Several wooden poles supporting nets on beach volleyball courts were bent landward orbroken.

3. Depressions (plunge pools) were formed in the pavement of a parking area on thelandward side of low steel fences within the parking area. The pools were elliptical with their longaxes in the N–S direction. 4. Some steel poles (1 m height) of a soft net fence were bent inland.5. Fishing boats were carried landward by up to several hundred meters.Return flows 1. Erosional channels formed by return flows widened seaward.

2. Many tiles (30 × 30 cm, 10 cm thick) from a 300-m-long tiled sidewalk alignedperpendicular to the beach were torn up by the run-up flow and deposited on the N side of thesidewalk. These were rearranged in imbricate structures by the return flow.3. Wooden poles supporting nets in some beach volleyball courts were bent seaward.

DiscussionRun-up flow

The run-up flows formed a strong surge, probably of 4 m height on the beach front, whichflowed over the backshore and damaged and distorted man-made structures there over arelatively brief time period. The total amount of sand eroded by the run-up flows may have beenless than that of the return flows, because sporadic areas of grass on the wide backshore wereexposed after the tsunami. Further inland, sand eroded by run-up flows was mainly depositedunder hedges.Return flow

Return flows had more time to exert their effects than run-up flows, and they eroded largevolumes of backshore sand, creating four or five seaward-widening erosional channels on thepreviously flat backshore (Fig. 1).

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Current system of the 2011 giant tsunami at Oarai Sun Beach

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FRENCH FLANDERS FIELDS: DECIPHERING THE HOLOCENE SEDIMENTARYHISTORY OF THE COASTAL PLAIN OF NORTHERN FRANCE

José MARGOTTA, Alain TRENTESAUX, Nicolas TRIBOVILLARD, Romain ABRAHAM

UMR 8217 GEOSYSTEMES, Bâtiment sn5 Cité Scientifique, 59655, Villeneuve D'Ascq, France,[email protected], [email protected],[email protected], [email protected]

The French Flanders Fields represent the southern end of the North Sea large coastal plainthat continues northward to the Danish coast. In this area, the Holocene infillings and theirsedimentary processes have been studied for decades, to decipher the stratigraphic successionand paleoclimatic changes that occurred during this period. However, in spite of severalstratigraphic analyzes that have been carried out in the area, it has not been possible yet toestablish a robust stratigraphic frame for the evolution of the Holocene.

In this sense, new integrative methodologies implemented in coastal areas, such as veryhigh-resolution seismic surveys, have allowed to reveal significant new information in contrast tothe studies based on isolated outcrops and boreholes. Integrating all these data in one datasetprovides the opportunity to develop a model to better describe the architecture of the subsurface.

In this view, a very high-resolution seismic survey was performed along the French Flemishwaterways open to navigation. The data consist in a series of seismic profiles that illustrate thefirst 30 meters of the subsoil and show distinctive features of the Holocene infillings.

Two stratigraphic units have been defined from the seismic profiles; they are separated byan unconformity surface with an unresolved chronostratigraphic position. Available boreholes andoutcrops display the internal characteristics of these stratigraphic units and give an insight into thecomposition of the substrate and the constant tidal influence. The integration of all the dataprovides some clues to understand the overall sedimentary processes at the origin of the depositsand the evolution of these lowlands.

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Location of study zone showing the French Flemish watercourses and indicating the distribution of seismicsurveys

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IMPACTS OF FLOODS AND CYCLONES ON MANGROVE OVER A SECTOR OF THESAVE RIVER DELTA PLAIN, MOZAMBIQUE

Elidio MASSUANGANHE*, Salomao BANDEIRA**, Lars-Ove WESTERBERG*

*DEPARTMENT OF PHYSICAL GEOGRAPHY AND QUATERNARY GEOLOGY, STOCKHOLMUNIVERSITY, Svante Arrhenius vag 8c, Frescati, SE106 91, Stockholm, Sweden,[email protected], [email protected]**DEPARTMENT OF BIOLOGICAL SCIENCES, FACULTY OF SCIENCES, EDUARDO MONDLANEUNIVERSITY, Av. Julius Nyerere 3453, 257, Maputo, Mozambique, [email protected]

Located in Southern Mozambique, the Save River delta plain is an example of estuarinedeltas with extensive mangrove forests that face threats of climate-related events. During the lastdecade Save River delta plain has been severely affected by recurring high-magnitude weatherevents (e.g. the 1999-2000 floods and cyclone, and the cyclones Japhet (2003) and Favio (2007))that prompted destruction in vegetation, notably on mangroves. However, the impact pattern ofthe mangrove degradation is unclear, given the multiple ways that the floods and cyclones act onthe study area. This study aims to assess the recent impacts of recurrent floods and cyclones inthe landscape over a sector of the Save River delta plain, with emphasis on mangrove andgeomorphology. Aerial photographs and Google Earth images of Save River delta wereinterpreted to find the geomorphological units. Additional field studies were undertaken tocomplement the interpretation and to evaluate the impacts of extreme weather events. Thegeomorphological map produced shows that the study area is composed mainly of beach sandand embryonic coastal dunes, beach ridges, marsh, alluvial plain and eluvial depressions (Fig. 1).The beach ridges are located in the northern part of the study area reflecting a progradingshoreline. Today, embryonic coastal dunes and sand beaches border the delta plain to the opensea, acting as a barrier for offshore winds and waves. Mangrove is distributed throughout thestudy area, but it is more luxuriant in the marshland and channel fill where a thick layer of muddysediments is available, and brackish water exchange is frequent. Mangrove dieback is evident indifferent areas, but most accentuated in the mouths of tidal outlet channels exposed to the opensea. At such locations (e.g. Waypoint 22 and 23, Fig. 1), extensive areas of the mangrove arephysically impacted by winds and waves (Fig. 1 B1) during the cyclone landfall. At this site,mangroves are also negatively affected by a chenier of beach sand deposited during cycloneEline (2000). In some sectors of the inland side of the barrier formed by beach sand andembryonic coastal dunes, the marshland was recently covered by a flush of sediments thatovertopped the barrier dune during extreme weather event (Fig. 1 B2). This has affected themangrove development negatively. On the other hand, other areas located on the sheltered sideof the spit (e.g. waypoint 115) show flourishing mangrove and a new mangrove nursery isdeveloping in a northerly direction as the spit grows and siltation takes place in the bay (Fig. 1B3). During floods the banks of the tidal channels experience accelerated erosion resulting inboth destruction of the terrestrial and mangrove vegetation on one side and sediment accretionon the other side. At the accreted areas mangrove flourishes. Vertical fine sand accretion in thewaypoint 107 was attributed to recent sediment reworking from the channel and it is affecting themangrove development negatively.

This work has shown the need to understand the geomorphological process dynamics inorder to accurately assess the net effects on mangroves of low-magnitude versus high-magnitudeweather events. The geomorphology controls the evolution pattern of mangrove forest as part ofthe normal landscape dynamic, but it also plays an important role controlling high magnitudeweather related events.

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A1- Map showing the main geomorphological unities of the study area; B1 – mangrove impacted directly bycyclone at the Waypoint 23; B2 – Marshland covered by dune sand from the barrier overtopping (Waypoint

103) and B3 – Very recent sheltered bay (at the right side of the photo) where new mangrove nurserydevelops.

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TRANSGRESSIVE, HEADLAND-ATTACHED TIDAL SAND RIDGES IN THE RODAFORMATION, NORTHERN SPAIN

Kain MICHAUD*, Robert W. DALRYMPLE**

*PETREL ROBERTSON CONSULTING LTD., Suite 500, 736 8th Ave. sw, T2P 1H4, Calgary, Alberta,Canada, [email protected]**DEPT. GEOL. SCI. & GEOL. ENG., Queen'S University, K7L 3N6, Kingston, Ontario, Canada,[email protected]

In modern shallow-marine settings, tidal currents are often an effective agent oftransgressive sea-floor reworking. Where sand is present in sufficient quantity and tidal currentsare fast enough, tidally moved sediment can accumulate to form transgressive sand ridges. Suchridges are often composed of well-sorted sand and can be overlain by shelf mudstone, makingthem a clear target for oil and gas exploration. While transgressive tidal ridges are abundant inthe modern, uncontested ancient counterparts are comparably few, largely because detailedstudies of their internal facies are rare. This presentation outlines the facies, internal architecture,and stratigraphic framework of 6 transgressive tidal ridges. The quality of outcrop exposure isexcellent, and allows collection of detailed information about the facies, paleocurrent patterns,internal architecture and stratigraphic positioning within regressive-transgressive cycles for all 6ridges.

The presence of tidal cross bedding in the Roda Member is well known (Nio 1976;Lopez-Blanco et al., 2003; Tinterri et al., 2007) and has been interpreted as being due toreworking of contemporaneous delta-front sands by tidal currents. New work, includingcomprehensive logging of the entire Roda Formation (including the overlying EsdolomadaMember), indicates that tidal sands accumulated at the distal end of 6 of the 18 progradationaltongues. Detailed outcrop mapping and tracing of the tidal sand bodies shows that they do notinterfinger with progradational delta lobes, but instead overlie and/or lie immediately seaward ofthe tip of the tongue, indicating they were deposited after deltaic progradation had ended, duringthe ensuing transgression.

The tidal sands are reconstructed as headland-attached sand ridges that are present onlyon those tongues that prograde more than 2 kilometers basinward: only these tongues protrudefar enough out into the basin to constrict the shore-parallel tidal currents sufficiently to cause tidalreworking of the delta lobe. Each ridge is situated immediately to the west of a deltaic headland,further implying local dominance of a westerly flowing ebb tide within the basin. As evidenced bypaleocurrent analysis for each of the ridges, the southwestern (offshore) side of each ridge wasdominated by the westerly flowly ebb current whereas the sheltered landward side of the ridgewas typically dominated by the easterly flowing flood tide. Accretion occurred on both sides of theridges, but with seaward accretion predominating. Facies are quite variable, ranging from ahigh-energy end member dominated by large-scale trough cross bedding to a low-energy endmember dominated by ripple cross-laminated sand.

Rates of subsidence, distance from the depocentre, current speed, sedimentation rate andwater depth are directly linked to facies variability and their stacking pattern within the ridges.

•Where subsidence rates were high (Esdolomada Member), sediment was effectivelytrapped in up-system estuaries during transgressions, allowing for carbonate drapes to form capson the ridges. Well-developed carbonate caps did not form during the Roda Member becausesubsidence rates were lower, allowing for more rapid progradation of the delta, limiting carbonateaccumulation on the ridges.

•In general, current speeds are highest at the ridge crest, such that the internal facieschange from cross-bedded sandstone at the crest to rippled sandstone and eventuallyinterlaminated sands and muds/silts at the toe of the ridge flanks.

•If the ridge grows high enough, strong tidal currents produce cross-ridge incision, formingswatchways.

•Sandy ridges with cross beds (high sedimentation rate) are less bioturbated than finergrained ridges composed of ripple cross lamination (coincident with a lower averagesedimentation rate).

•Neap-spring cyclicity visibly affects the preserved bioturbation intensity and diversity withinbed-sets. The thin tidal bundles deposited during neap-tide periods are significantly morebioturbated than the thicker bundles formed during spring tides.

Changes in environmental conditions that accompanied the transgression are sometimes,but not always, recorded within the ridges. Some ridges were drowned (relative sea-level rise

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outpaced ridge growth) and are mantled by lower-energy sandy facies deposited as the ridgebecame moribund. More rapidly growing ridges, by contrast, retain a core of lower energydeposits draped by shallower-water deposits.

Simplified proximal-distal cross section of the Roda Formation, showing the stratigraphic and geographiclocation of the headland-attached transgressive sand ridges (yellow).

LOPEZ-BLANCO, M., MARZO, M., and MUNOZ, J.A., 2003, Low-amplitude, synsedimentary folding of adeltaic complex: Roda Sandstone (lower Eocene), South-Pyrenean Foreland Basin: Basin Research, v. 15,p. 73-95.NIO, S.D., 1976, Marine transgressions as a factor in the formation of sandwave complexes: Geologie EnMijnbouw, v. 55, p. 18-40.TINTERRI, R., 2007, The lower Eocene Roda Sandstone (south-central Pyrenees): An example of aflood-dominated river-delta system in a tectonically controlled basin: Rivista Italiana di Paleontologia eStratigrapfia, v. 113, no. 2, p. 223-255.

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LATE QUATERNARY STRATIGRAPHY AND MORPHODYNAMICS OF MACROTIDALSAND BODIES IN THE WESTERN COAST OF KOREA

Soo Chul PARK

DEPARTMENT OF OCEANOGRAPHY, CHUNGNAM NATIONAL UNIVERSITY, Gung-Dong 220,Yuseong-Ku, 305-350, Daejeon, Korea, [email protected]

The west coast of Korea (eastern Yellow Sea) is a well-known macrotidal environment withtidal ranges of up to 9 m. Sand bodies are prominent sedimentary features in this area and mostof them occur either as a series of linear or individual sand bodies. The shelf sand bodies arepresent in water depths of 50–90 m and show large, elongate shapes with a length up to 200 km.In contrast, the nearshore sand bodies are much smaller in size (up to 34 km length) and occur inwater depths shallower than about 30 m. In this study, we analyze a number of sediment cores,high-resolution seismic (sparker) profiles and side-scan sonar images to understand thestratigraphy and morphodynamics of these sand bodies, using radiocarbon datings to constrainthe ages of the ridges.

The coastal sand bodies above the acoustic basement can be divided into threestratigraphic units (N1, N2, and N3 in a descending order) based on the mid-reflecors andacoustic characters. The upper unit (N1) is the main body of the ridges with a thickness of 5-25m, which formed during the recent highstand of sea-level (<5,000 yrs B.P.). The middle unit isless than 10 m in thickness and represents the estuarine or intertidal deposits produced duringthe last stage of sea-level rise (5,000-7,000 yrs B.P.). The lower unit (N3) consists ofsemi-consolidated mud with a thickness less than 15 m. This unit is interpreted to representremnants of the last interglacial tidal deposits.The shelf sand bodies are also divided into threestratigraphic units (S1, S2, and S3 in a descending order). The surface (S1) and middle (S2) unitsconstitute the main sand body of the ridges, with a thickness up to 25 m. The middle unit (S2) isinterpreted to have formed in the course of postglacial transgression, possibly during theepisodes of stillstand or significant slowdown of sea–level rise. However, the ridge surface hasbeen continuously reworked by modern tidal currents to produce a thin (< 5 m) surface sand layer(S1). The lower unit (S3) forms the substratum of the shelf sand ridges and displays variations inthickness (5–20 m). The shelf sand ridges more or less result from an erosional processdominantly acting during the postglacial transgression.

Large dunes on the nearshore sand bodies indicate a strong hydrodynamic influence on theentire surface at present. Tidal-currents model show that the net deposition and erosion pattern ofsands tends to correspond to areas of shoals and deeper water depths, respectively, suggestingthe maintenance of shoals by the tidal currents. It would appear that all of the coastal sand bodieshave undergone the same erosional shaping of their form during the recent highstand of sealevel.

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Seismic profiles of the nearshore (top) and shelf (bottom) sand bodies

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RHYTHMIC CLIMBING RIPPLES LAMINATION FROM MODERN (BAY OF THEMONT-SAINT-MICHEL, FRANCE) AND ANCIENT (DUR AT TALAH, PALEOGENE,

LIBYA) TIDAL DEPOSITIONAL ENVIRONMENTS: DESCRIPTION, GENESIS,SIGNIFICANCE AND NEW CRITERION FOR TIDAL EVIDENCE

Jonathan PELLETIER*, Ashour ABOUESSA*, Philippe DURINGER*, Mathieu SCHUSTER*,Jean-François GHIENNE*, Jean-Loup RUBINO**

*INSTITUT DE PHYSIQUE DU GLOBE DE STRASBOURG (IPGS)-UMR 7516; UNIVERSITE DESTRASBOURG (UDS)/EOST/CNRS, 1 rue Blessig, 67084, Strasbourg, France,[email protected]**TOTAL, CENTRE SCIENTIFIQUE ET TECHNIQUE JEAN FEGER, Avenue Larribau, 64000, Pau, France

The New Idam Unit of the Dur At Talah Formation is known to have been deposited in atidal environment (Abouessa et al., 2012; Pelletier et al., 2012a this congress). Some of theassociated deposits display typical Rhythmic Climbing Ripple (RCR; Choi, 2010) sequences.

From a distance, RCR laminations look like classical climbing ripples laminations, but acloser observation reveals alternations of sand and mud laminations which suggest that they formstep by step (i.e. rythmically) rather than continuously. RCR have been described from modernenvironments (Lanier and Tessier, 1998; Choi, 2010) and rarely reported from the geologicalrecord (Lanier and Tessier, 1998; Chanda and Bhattacharyya, 1974). This work displaysRhythmic Climbing Ripple structures from both modern (MSM) and ancient (DAT) tidal systemsand reveals RCR as being a key feature to identify tide-driven depositional process.

For both cases, RCR sequences are characterized by rhythmic gradual thinning andthickening of cross-laminae expressed by neap-spring tidal cycles, indicating a strong control bytidal dynamic. A fine observation of modern Mont-Saint-Michel Bay RCR shows that they are,most of the time, generated in upper intertidal domain in inclined heterolithic stratification (IHS) oftidal channels. Indeed, RCR record flood and ebb markers; the morphologic dissymmetry is dueto the asymmetric energy between dominant and subordinate currents. Mud couplets,corresponding to the slack water phases of flood and ebb tides, should give evidence ofsubaquatic genesis but it seems that the mud drape corresponding to the ebb slack water is anintermediate settling of mud occurring during the ebb tide way down. These structures are formedin a narrow interval in tidal channel IHS indicative of a precise elevation. Moreover, newdiagnostic criteria of morphology have been observed to define these ripples. For example, a newrecognition criterion for tidal dynamic was deducted and observed in these structures; in most ofcases, the RCR lee sides seem notably eroded, contrary to conventional climbing ripples.

This study is principally focused on the centimetric to decimetric-scaled description of thesesedimentary structures as well as the comparison with ancient series. These are also indicative ofpaleogeography. This work tries to demonstrate and suggests first, indirectly, that macro tomesotidal regime of the Tethian Sea prevailed on the Sirtic paleocoast, that these structures wereformed in intertidal and/to subtidal domain respectively in MSM Bay and in Libyan deposits, andfinally, that the tidal regime of the Tethian Sea in the Sirt embayment was certainly semi-diurnal.

This comparison between modern MSM Bay facies and ancient DAT facies seems to be agood tool to restrict environment and dynamic conditions and reveals RCR are a robust criterionto identify tidal dynamic.

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Comparison between modern RCR from the Mont-Saint-Michel Bay (MSM) and ancient RCR from the DurAt Talah (DAT): (A) Rhythmic climbing ripple (RCR) sequence showing a neap-spring cyclicity (N-S), note

the slight lee-side erosion (black arrows) and the ripple cap (c) generated by a subordinate current; (B)Modern RCR sequence showing exactly same characteristics than A; (C) Close-view of ripple laminations

underlined by double mud drapes (yellow and red lines) generated by slack water periods (of ebb andflood); (D) Close-view of modern RCR exposing well-preserved double mud drapes, note the slight lee-side

erosion.

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THE GEOLOGICAL RECORD OF TIDAL DYNAMIC: DIVERSITY OF ASSOCIATEDDEPOSITS AND MULTI-SCALE CYCLES FROM THE DUR AT TALAH FORMATION

(UPPER EOCENE, SIRT BASIN, LIBYA)

Jonathan PELLETIER*, Ashour ABOUESSA*, Philippe DURINGER*, Mathieu SCHUSTER*,Jean-Loup RUBINO**

*INSTITUT DE PHYSIQUE DU GLOBE DE STRASBOURG (IPGS)-UMR 7516; UNIVERSITE DESTRASBOURG (UDS)/EOST/CNRS, 1 rue Blessig, 67084, Strasbourg, France,[email protected]**TOTAL, CENTRE SCIENTIFIQUE ET TECHNIQUE JEAN FEGER, Avenue Larribau, 64000, Pau, France

Dur At Talah sequence is outcropping in the Abu Tumayam Trough, in the southern part ofthe Sirt Basin (Libya). This formation consists of tidal marine deposits at the base (New IdamUnit) and fluvial deposits at the top (Sarir Unit). This stratigraphic succession highlights aregressive trend attributed to the upper Eocene (Abouessa et al., 2012).

Sedimentological investigations based on lithofacies and ichnofacies suggest that thedepositional environments were mainly dominated by a tidal dynamic. Characterization of thistidal dynamic is focused on diagnostic sedimentary structures and their associated sequences.Several paleoenvironments have been defined for the New Idam Unit: the basal part of this unit isbuilt up of an intertidal to supratidal flat system associated with oyster patches. The medium partis characterized by an estuarine channels belt. The upper part of the New Idam Unit exposestypical facies of tidal flats and prograding bar system (mouth bars?). The extremely good qualityof preservation of sedimentary structures and sequences allows to investigate the recording oftidal cycles at various scales of time, from the elementary tidal cycle to the solsticial cycles. Acomparison between modern Mont-Saint-Michel Bay facies and ancient Dur At Talah facies wasproposed to calibrate facies and paleoenvironments.

These tidal cyclicities are recorded through several sedimentary structures and laminationmorphologies. Tidal overprint can be expressed inside horizontal laminations, ripples (flaser, wavyor lenticular) as well as megaripples. And this spectrum of morphologies is preserved intosedimentary bodies such as inclined heterolithic stratifications (IHS) of tidal channels.

The elementary recording is made of mud-sand couplet corresponding to one tide event(slack and flood/ebb). The next scale recording corresponds to the neap-spring cycle and it ischaracterized by a contraction-dilation of ripple bundles. Finally, a higher wavelength cycle isrecognizable, likely corresponding to a solsticial cyclicity. All these cycles have been identified forlarge-scale sedimentary bodies attributed to tidal channels and are best expressed within IHS.These cycles can be used as a chronometer for the timing of tidal channel migration and channelinfilling. From a basic calculation based on the tidal cycle counting, a hypothetic migration ratewas deduced.

Calculation of tidal cycles recorded inside IHS gives a lateral migration rate between 0,4 to2 m/month and a channel infilling average between 15-20 years. This postulate is valid for Dur AtTalah tidal channels and probably for equivalent in size and hydrodynamic parameters (e.g. tidalrange) modern tidal channels. Finally, modern analogue such as Mont-Saint-Michel Bay facies isa good tool to compare tidal cyclicities and tidal structures and were useful forpaleoenvironmental reconstruction.

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(A) Inclined heterolithic Stratifications (IHS) of tidal Channel; (B) Tidalite pin-stripe facies in verticalaccretion; (C) Neap (n)/spring (s) cyclicity recorded in tidal channel facies; (D) Flaser bedding showing the

bidirectionality of elementary ebb and flood curents (black arrows).

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TIDE-INFLUENCED FLUVIAL-DELTAIC SEDIMENTS VERSUS CONTINENTALSANDY-MUDDY FLAT DEPOSITS: EVIDENCE FROM THE HUERTELES FM (EARLY

CRETACEOUS, N SPAIN)

I. Emma QUIJADA, Pablo SUAREZ-GONZALEZ, M. Isabel BENITO, Ramón MAS

STRATIGRAPHY DPT.-COMPLUTENSE UNIV. OF MADRID-IGEO (CSIC-UCM), José Antonio Novais 2,28040, Madrid, Spain, [email protected]

Recognizing and interpreting features attributable to tidal influence in the sedimentaryrecord may be difficult in certain tidal settings, such as fluvial-tidal transition estuaries, fluvial-tidaldeltas and protected inland tidal embayments (e.g. Kvale & Archer, 1990; Gingras, 2002;Hovikoski, 2005, Rebata et al., 2006). In these settings, clear evidence of tidal influence, such astidal bundles, herringbone structures or biological features, may be absent. Mixedsiliciclastic-carbonate Huérteles Fm, from the Cameros Basin (Early Cretaceous, N Spain), posesa challenging sedimentological problem as it displays several features suggesting tidal influencebut some other evidences, such as marine biota, are lacking.

The Huérteles Fm was deposited during the Berriasian in the Cameros Basin, a Tithonian toAlbian rift basin situated in northern Spain. This basin comprises more than 9000m ofstratigraphic record, including essentially alluvial, fluvial and lacustrine deposits (Mas et al.,2002). This record has been subdivided in 8 depositional sequences limited by unconformities(Mas et al., 2002): the Huérteles Fm is part of the third one.

The Huérteles Fm consists of siliciclastic deposits in the central area of the basin andchanges to coeval carbonate-evaporitic deposits to the eastern area. The siliciclastic deposits,made up of channelled sandstones, laminated mudstones and fine-grained sandstones, havebeen interpreted as deposited in continental sandy-muddy flats and meandering fluvial systems(Gómez-Fernández & Meléndez, 1994). Several sedimentary features, such as sandstonechannelled beds and mudcracked laminated lutites, the lack of marine fossil remains and thepresence of reptile fossil remains and footprints (Fig. 1) led to interpret these siliciclastic depositsas formed in a continental setting. In addition, carbonates and evaporites, laterally related andinterbedded with the siliciclastics, do not contain marine fossils and do not display sedimentaryfeatures clearly indicating a marine depositional setting. They are made up of laminatedcarbonates and evaporites (Fig. 2-3) and massive carbonates with large pseudomorphs aftergypsum. Their fossil content is limited to stromatolites, ostracods and occasional charophytes.

Nevertheless, several sedimentary structures of the siliciclastic deposits lead us to adifferent interpretation. The presence of inclined heterolithic stratification (IHS) within channelledbeds (Fig. 4), abundant flaser, wavy and lenticular stratification (frequently within the IHS) (Fig.5-6), rhythmic alternations of sandstones and lutites (Fig. 5) and occasional bi-polar currentindicators suggest that these siliciclastic deposits were formed in tidally-influenced fluvial-deltaicenvironments. In such context, the carbonate and evaporite deposits would have been formed ina coastal environment. Marine influence in these carbonate-evaporitic areas is consistent with thelarge input of sulphate ions into these settings and with ostracod assemblages indicating mixedfresh and brackish water environments (Schudack & Schudack, 2009).

The absence of marine fossils in the Huérteles Fm needs not be explained by a continentalsetting. Instead, a fresh to brackish tidal environment, such as the Upper San FranciscoEstuary/Sacramento Delta (California) during the late Holocene (Wells & Goman, 1995), couldexplain this lack of marine organisms. Some other reasons for the scarcity of biota in theproposed sedimentary environments may be high sedimentation rates, rapid salinity fluctuationsand acidic ground or surface waters (Kvale & Archer, 1990).

The Colorado River Delta and the Tigris-Euphrates Delta could represent two present-dayanalogues for siliciclastic tidal environments laterally related to evaporitic depositional settingssimilar to the proposed for the Huérteles Fm. However, in both modern analogues, the evaporitesare interbedded with siliciclastics, while in the studied unit, they are interbedded with carbonates.Probably a wide and restricted area where siliciclastic discharges were scarce developed in theeastern Cameros Basin, allowing particularly deposition of carbonate and evaporite in this moredistal zone.

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Gingras, M.K., Räsänen, M. & Ranzi, A., 2002. Palaios 17, 591-601.Gómez-Fernández, J.C. & Meléndez, N., 1994. Journal of Paleolimnology 11, 91-107.Hovikoski, J., 2005. Geology 33, 177-180.Kvale, E.P. & Archer, A.W.,1990. Journal of Sedimentary Petrology 60, 563-574.Mas, R., Benito, M.I., Arribas, J., Serrano, A., Guimerà, J., Alonso, A. & Alonso-Azcárate, J., 2002. Zubía14, 9-64.Rebata-H., L.A., Gingras, M.K., Räsänen & M.E. Barbieri, M., 2006. Sedimentology 53, 971-1013.Schudack, S. & Schudack, M., 2009. Journal of Iberian Geology 35, 141-168.Wells, L.E. & Goman, M., 1995. In: Isaacs & Tharp (eds.), Proceedings of the 11th Annual Pacific Climate(PACLIM) Workshop, 185-198.

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UNDERSTANDING THE DEPOSITION OF TIDALLY DEPOSITED MUDSTONES: ANEXAMPLE FROM THE TILJE FORMATION (JURASSIC), OFFSHORE NORWAY

Geoff REITH*, Robert W. DALRYMPLE*, Duncan MACKAY**, Aitor ICHASO***

*DEPT. GEOL. SCI. & GEOL. ENG., Queen'S University, K7L 3N6, Kingston, Ontario, Canada,[email protected], [email protected]**P1 ENERGY, Suite 700, 440 - 2nd ave sw, T2P 5E9, Calgary, Alberta, Canada,[email protected]***SHELL CANADA LTD., 400 - 4th ave sw, T2P 2H5, Calgary, Alberta, Canada, [email protected]

Our understanding of tidally transported and deposited mud has been reshaped over thelast two decades. It is now recognized that not all mud deposition is by passive settling; indeed,mud can accumulate under dynamic conditions where current velocities are above the thresholdof mud erosion, provided there are high-density (i.e., > 1 g/L) near-bed mud suspensions (Baas etal., 2009, 2011; Schieber and Southard, 2009). Such high-density suspensions, and especiallyfluid mud (> 10 g/L), are now known to occur in many different tidal environments, and may evenbe an indicator of significant tidal action. Ichaso and Dalrymple (2009) have provided generalcriteria for identifying fluid-mud deposits in the rock record. Using core from the Tilje Formation,an Early Jurassic, mixed-energy (tide- and river-influenced) deltaic succession, thick (up to 15cm), slack-water mud layers at the base of tidal-fluvial channels and in mouth-bar deposits havebeen interpreted as the product of fluid muds deposited during tidal slack-water periods. It wasassumed that they accumulated by passive settling, but is now known that generally similar, thickmudstone layers can accumulate dynamically (Mackay and Dalrymple, 2011). Therefore, wehave undertaken a more detailed investigation of the Tilje fluid-mud layers using thin sections, todetermine whether they too were deposited by dynamic processes. This study reveals thepresence of three main mudstone “facies” within the fluid-mud layers.

UNSTRATIFIED MUDSTONE (UM)This facies consists of thick claystone and siltstone laminae (5-10 mm thick) and beds (>

10mm thick) that do not contain any internal laminations. They are interpreted to have formedduring periods of moderate (1-10 g/L) to high (>10 g/L) SSC levels where near-bed turbulence iscompletely suppressed by a “plug” (a strong cohesive network of clay floccules) (Mackay andDalrymple, 2011). The lack of internal lamination is accounted for by the lack of turbulence,which is required as a sorting mechanism. This facies was classified as a fluid mud by Ichasoand Dalrymple (2009). Two sub-facies are recognized. 1)Without floating sand grains 2)With floating sand grains

The presence or absence of floating sand grains in a plug depends on the cohesivestrength of the suspension. Baas et al. (2011) noted that the critical value occurred at SSC levelsfrom ~315 g/L to 430 g/L: at values below this, the sand grains sink to the bottom, whereas, fromthese values and above, the sand grains cannot sink. In some cases the dispersed sand grainsmay appear to be graded; however, this is due to differential ability to sink through the suspensionand is not due to turbulent sorting.

CROSS-LAMINATED MUDSTONE (CLM)These mudstone layers contain small-scale cross lamination as a result of bedload

transport of material. Moderate (1-10 g/L) SSC levels were shown to deposit mud dynamically influme studies by Schieber and Southard (2009), where mud flocs can be transported in bedloadand deposited as floccule ripples. Two varieties exist.

1)Mud Ripple Laminations: This cross laminations consists solely of fine to very fine siltand clay, and occurs in small low-angle sets (3-5 mm thick). They are thought to be formed byfloccule ripples and have been flattened due to the high degree of compaction.

2)Mixed Grain-size Ripple Laminations: In systems where silt and fine sand are able to betransported in bedload together with flocculated mud, mixed grain-size laminations may form. Typically these sets are thicker and are more easily recognizable in thin-section than flocculeripples.

PLANAR-LAMINATED MUDSTONE (PLM)Planar-laminated mudstones are common in the Tilje Formation, and many intervals

interpreted by Ichaso and Dalrymple (2009) as unstratified are indeed laminated when observedin thin section. Many physical mechanisms have been proposed for the formation of thesecomplex laminations. Two sub-facies have been created.

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1)Continuous Lamination: Non-bioturbated alternating laminae of clay and silt wereinterpreted by Mackay and Dalrymple (2011) to have formed underneath a plug in a flow with highSSC levels and mixed turbulent and laminar forces. Many of their examples underlay unstratifiedmudstone (UM); however, the Tilje Formation does not always display this pattern. Therefore, ifcontinuous laminations occur below an UM, they likely formed at high SSC levels, but if there isno overlying UM, it is possible that the continuous laminations formed in a flow with lower SSClevels.

2)Non-continuous Lamination (Grain Clusters): Non-continuous laminations occur asseveral millimeters-long sand/silt clusters that are capped with clay. Many of these clustersappear to have accumulated in a similar manner to pebble clusters in gravel rivers. This indicatesthat turbulence must have been present at the bed and they, thus, are likely to have accumulatedat lower SSC levels. Some examples of this feature appear to indicate current direction becauseof grain imbrication.

Cyclic variations in flow strength and SSC levels are recorded within some mudstone layersby vertical changes in the facies. Figure 1, a sample deposited in a tidal channel in the Tilje Fm.,has been interpreted to contain a complete tidal cycle.

Baas, J.H., Best, J.L., Peakall, J., and Wang, M., 2009, A phase diagram for turbulent, transitional, andlaminar clay suspension flows: Journal of Sedimentary Research, v. 79, p. 162–183.Baas, J.H., Best, J.L., and Peakall, J., 2011, Depositional processes, bedform development and hybrid bedformation in rapidly decelerated cohesive (mud–sand) sediment flows: Sedimentology. doi:10.1111/j.1365-3091.2011.01247.x.Ichaso, A.A., and Dalrymple, R.W., 2009, Tide- and wave-generated fluid mud deposits in the TiljeFormation (Jurassic), offshore Norway: Geology, v. 37, p. 539–542.Mackay, D.A., and Dalrymple, R.W., 2011, Dynamic mud deposition in a tidal environment: the record offluid-mud deposition in the Cretaceous Bluesky Formation, Alberta, Canada: Jour. Sed. Res., v. 81, p.901-920.Schieber, J., and Southard, J.B., 2009, Bedload transport of mud by floccule ripples-direct observation ofripple migration processes and their implications: Geology, v. 37, p. 483–486.

106


OFFSHORE TIDAL BIOCLASTIC BODIES IN EPEIRIC SEAS: MIOCENE EXAMPLESFROM SE FRANCE AND CORSICA

Jean-Yves REYNAUD*, Jean-Loup RUBINO**, Olivier PARIZE***, Robert W. DALRYMPLE****,Emmanuelle VENNIN*****, Michelle FERRANDINI******, Jean FERRANDINI******, Jean-Pierre

ANDRE*******, Bernadette TESSIER********, Noel JAMES****

*MUSEUM NATIONAL D'HISTOIRE NATURELLE, Dht-43 rue Buffon, 75005, Paris, France, [email protected]**TOTAL, CENTRE SCIENTIFIQUE ET TECHNIQUE JEAN FEGER, Avenue Larribau, 64000, Pau, France***AREVA NC, 1 Place Jean Millier, 92084, Paris la Défense, France****QUEEN'S UNIVERSITY, Dept Geological Sciences, ONK7L3N6, Kingston Otario, Canada*****UNIVERSITE DE DIJON, 6 Boulevard Gabriel, 21000, Dijon, France******UNIVERSITE DE CORSE, Bp52, 20250, Santa-Lucia-Di-mercurio, France*******UNIVERSITE D'ANGERS, 2 bd Lavoisier, 49000, Angers, France********UMR CNRS 6143 M2C, UNIVERSITE DE CAEN, 24 Rue des Tilleuls, 14000, Caen, France

In the Lower and Middle Miocene, the northern part of the Western Mediterranean and mostof the western perialpine foreland basins experienced strong tides, which were locally enhancedwhere the tidal flows were entrenched in narrow seaways or straits. The resulting deposits aremixed siliciclastic to dominantly bioclastic crossbedded successions, several tens of meters thickand about several kilometers in extent which where formed by the stacking of subtidal dunes. InFrance these rocks are famous since the Romans used them to build the roman bridge over theGard River (photo). Although most of the bioclastic grains in each unit were derived from thesame heterozoan carbonate factory (dominated by bryozoans to coralline algae), they weresorted by tidal currents and residual faunal assemblages depict vertical and lateral trends that canbe interpreted in terms of current strength, proximal-distal relationships and high-frequencysea-level changes.

These tidal deposits are mostly comprised within TSTs but also locally in FRSTs. Thehistorical stratotype of the Burdigalian in the foreland basin of SE France is an overalltransgressive stack of high frequency sequences of crossbedded calcarenites, which have beeninterpreted as tidal bars and channel-fills (Lesueur et al., 1990). In the Vénasque valley, the tidaldeposits are confined within the walls of the valley, and topped by storm-influenced marls thatoverlap the valley interfluves (Besson et al., 2005). This points to the dominant control of tidal flowconstriction on the localization of the tidal deposits. Similarly, tidal deposits are emplaced as aflood-tidal delta at the outlet of the Uzès-Castillon valley into Uzès Basin (Reynaud et al., 2006).This is explained as the consequence of tidal flow expansion into the basin. The tidal inlet isplugged by very large tidal dunes.

In the Sommières Basin, which had the same paleogeography as Uzès Basin, storminfluenced deposits are found at the base of the TST below the tidal dunes. This shows, inaddition to the dominant role of constriction or expansion of tidal flows, a local control by relativesea-level. The tidal climax was, in that case, the time of maximum tidal prism in the course ofsea-level rise. At larger scales, tectonics also controlled the non-tidal to tidal switch of offshoredynamics in those basins. In the Bonifacio Basin (André et al., 2011; Reynaud et al., 2012), anagradational tide-dominated sand sheet composed of dunes replaced a wave-dominated rampafter the strait separating Corsica and Sardinia abruptly deepened, at the end of the opening ofthe Western Mediterranean.

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The roman bridge over the Gard River is made up of Miocene tidal calcarenites, extracted from apaleovalley incised in the Lower Cretaceous platform carbonates (which form the bedrock outcropping on

this picture).

André J.-P., Barthet Y., Ferrandini M., Ferrandini J., Reynaud J.-Y. & Tessier B. (2011) The BonifacioFormation (Miocene of Corsica): Transition from a wave- to tide-dominated coastal system in mixedcarbonate-siliciclastic sediments. Bull. Soc. Geol. Fr., 182, 225-234 Besson D., Parize O., Rubino J.-L., Aguilar J.-P., Aubry M.-P., Beaudoin B., Berggren W.A., Clauzon G.,Crumeyrolle P., Dexcoté Y., Fiet N., Iaccarino S., Jimenez-Moreno G., Laporte-Galaa C., Michaux J., vonSalis K., Suc J.-P., Reynaud J.-Y. & Wernli R. (2005) Un réseau fluviatile d’âge Burdigalien terminal dans leSud-Est de la France : remplissage, extension, âge, implications.- C.R. Géoscience, 337, 1045-1054. Lesueur J.-L., Rubino J.-L. & Giraudmaillet M. (1990) Organisation et structures internes des dépots tidauxdu Miocène rhodanien. Bull. Soc. Geol. Fr., 6, 49-65.Reynaud J.-Y., Dalrymple R.W, Vennin E., Parize O., Besson D. & Rubino J.-L. (2006) Topographiccontrols on producing and depositing tidal cool-water carbonates, Uzès basin, SE France. J. Sed. Res., 76,117-130.Reynaud J.-Y., Ferrandini M., Ferrandini J., Santiago M., Thinon I., André J.-P., Barthet Y., Guennoc P. &Tessier B. (2012) From non-tidal shelf to tide-dominated seaway: the Miocene Bonifacio Basin, southernCorsica. Sedimentology, in press.

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COMPOUND TIDAL DUNES IN THE NEUQUEN JURASSIC RIFT BASIN

Valentina ROSSI, Ronald STEEL, Cornel OLARIU, Julio LEVA LOPEZ

JACKSON SCHOOL OF GEOSCIENCE, UNIVERSITY OF TEXAS AT AUSTIN, 1 University StationC9000, 78712, Austin, Usa, [email protected], [email protected],[email protected], [email protected]

As part of a larger collaborative project revisiting the origin of the 500 m-thick, BajocianLajas Formation in the Neuquén Basin of Argentina, the present work reports on the distal deltafront to shelf portion of the lower Lajas Formation, exposed in a 6 Km long outcrop belt at LohanMahuida.

The studied unit is characterized by stacked, cross-stratified sandbodies and is sand-richwith relatively thin intervening mudstones.

Detailed stratigraphic sections, linked to high resolution photo-mosaics, provide correlationand definition of the architecture of the sedimentary bodies. Three sandstone bodies (Fig. 1)have been selected for detailed study and 3D photos and LIDAR data have been acquired. Thesecross-stratified bodies have average thickness of 3, 5.5 and 15 m respectively; they are generallycapped by heterolithic, thinly laminated facies , which can pass upwards to storm-wavegenerated sandstones or fine-grained sediments.

Hundreds of paleocurrent indicators have been collected to determine the accretion style ofthese bodies (forward versus lateral accretion) in order to discriminate between compound tidaldunes and tidal sand ridges. To accomplish this, a hierarchy of inclined surfaces have beendiscriminated within the sandbodies (Fig. 2a and 2b): first order master surfaces or downlapsurfaces, second order foreset surfaces of large dunes and third order foresets of small duneswithin the larger ones. If the growth style of the sandbody is lateral accretion, the angle betweenmaster surfaces and second/third order surfaces would be significant, and usually greater than60°. In the selected sandbodies there was little deviation between the dip azimuth of the mastersurfaces and the two sets of dunes, indicating that the sandbodies are compound dunes (Fig. 3).The bodies are therefore likely to be elongate perpendicular to the main tidal current directionrather than parallel to it.

The analyzed succession is mainly unidirectional, with very few indicators of bidirectionality.This characteristic can possibly be explained in a shelfal environment, where the tidal currentsare mainly rotary. An alternative explanation is that flood tidal currents, just seaward of the deltas,dominated.

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MONSOON-CONTROLLED DELTAIC SEDIMENTATION IN A TIDE-DOMINATEDSETTING: EXAMPLES FROM MEGA-DELTAS IN ASIA

Yoshiki SAITO

GSJ/AIST, Higashi, 305-8567, Tsukuba, Japan, [email protected]

Sediment discharge from rivers to the ocean and sediment dispersal in coastal zones inAsia are mainly controlled by the monsoon. The monsoon climate is characterized by a rainysummer with prevailing south winds and a dry winter with strong north winds in Asia. More than70–80% of annual sediment discharge occurs in summer, and re-suspension of sediment in thecoastal zone by waves is dominant in winter. These characters are well recognized in the YellowRiver Delta, Yangtze River Delta and Mekong River Delta. Here I review recent studies on thesedeltas and show an example of seasonal changes of sediment delivery and dispersal in atide-dominated setting from the Mekong River Delta in Vietnam.

The Mekong River Delta in Vietnam and Cambodia is one of largest deltas in the world witha delta plain that is about 300 km wide plain in a wave-tide dominated setting (mesotidal).Repeated surveys between November 2005 and March 2012 along shore-normal beach transectshave shown that muddy sediment delivery occurs in summer, resulting in thick mud distribution onupper parts of the delta-front platform at the river mouth and a slightly muddier beach. Duringsummer, the wave direction is relatively weak southwesterly. However, mud and very fine sand inthe surface sediments tend to be removed during winter, suggesting that the sediment suppliedfrom the river during summer is temporarily deposited near the river mouth and later transportedsouthwestward during the winter monsoon. This feature coincides with the long-term sedimentdistribution and strata formation of the Mekong River Delta.

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Location and geomorphology of the Mekong River Delta with Optically stimulated luminescence (OSL) andradiocarbon ages (After Tamura et al., 2012)

A: Location of Mekong River delta. Locations of sediment drill cores reported by previous studies areshown. B: Geomorphology of Mekong River delta (simplified from Nguyen et al., 2000; Tamura et al., 2010)

and bathymetry of coastal sea relative to mean sea level (Ta et al., 2005). Beach ridges were redefinedusing Landsat image taken in 1989. Delta-front platform extends from shoreline to 4-m-deep isobath,

offshore of which is delta-front slope. Delta-front slope grades offshore into prodelta and shelf at waterdepth of 18–20 m. Optically stimulated luminescence (OSL) and radiocarbon ages are expressed relative to

A.D. 2010.

Nguyen, V.L., Ta, T.K.O., and Tateishi, M., 2000. Late Holocene depositional environments and coastalevolution of the Mekong River Delta, southern Vietnam. Journal of Asian Earth Sciences, vol. 18, pp.427–439, doi:10.1016/S1367-9120(99)00076-0.Ta, T.K.O., Nguyen, V.L., Tateishi, M., Kobayashi, I., and Saito, Y., 2005. Holocene delta evolution anddepositional models of the Mekong River delta, southern Vietnam, in Giosan, L., and Bhattacharya, J.P.,eds., River deltas—Concepts, models, and examples: Society for Sedimentary Geology Special Publication83, pp. 453–466.Tamura, T., Horaguchi, K., Saito, Y., Nguyen, V.L., Tateishi, M., Ta, T.K.O., Nanayama, F., and Watanabe,K., 2010. Monsoon-influenced variations in morphology and sediment of a mesotidal beach on the MekongRiver delta coast: Geomorphology, vol. 116, pp. 11–23, doi:10.1016/j.geomorph.2009.10.003.Tamura, T., Saito, Y., Nguyen, V.L., Ta, T.K.O., Bateman, M.D., Matsumoto, D., Yamashita, S., 2012.Origin and evolution of inter-distributary delta plains, insights from Mekong River delta. Geology, vol. 40,no. 4, pp. 303–306, doi:10.1130/G32717.1

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MEANDERING TIDAL CHANNEL DEPOSITS IN THE FLUVIAL-TIDAL TRANSITIONOF A MIOCENE ESTUARY IN PATAGONIA

Roberto SCASSO*, José Ignacio CUITIÑO*, Teresa DOZO**, Pablo BOUZA**

*DEPARTMENT OF GEOLOGICAL SCIENCES, Intendente Guiraldes 2160, Ciudad Universitaria,,C1428EHA, Pabelón ii, Argentina, [email protected], [email protected]**CENPAT, CONICET, Boulevard Brown 2915, U9120ACD, Puerto Madryn, Argentina,[email protected], [email protected]

La Pastosa beds constitute a nice example of sediments deposited in the highlymeandering reach of the of fluvial-tidal transition (Dalrymple and Choi, 2007; van den Berg et al.,2007) within an estuary developed at the top of the “Rionegrense”, a marine-estuarine sequenceof Late Miocene age in northeast Patagonia (Scasso and del Río, 1987; Scasso et al., 2001;Dozo et al., 2010). Sedimentary facies like channel lags rich in rip-up boulders and mudintraclasts, cross-bedded sands with mud drapes and “set-climber” ripples, inclined (HIS)andhorizontal heterolithic stratification, herringbone bedding and tidal rhythmites, together withpaucity of bioturbation and marine fossils, indicate that sedimentation took place in tidal channelssubjected to strong tidal influence bounded by deposits formed in transgressive conditions at thebase and at the top of the succession (Figure 1).

Channel lag intraformational conglomerates are product of collapse of the cutbank due toerosion in the active margin of meandering channels. Cross-bedded sands accumulate in deeperparts of the channel and IHS formed in point bars. Discontinuities at the base of the channels andat the base of large IHS sets are the result of the migration of the whole channel-system andseasonally increased run-off and widening of the channel, respectively. Thick mud drapes andmud pebbles point to high suspended-sediment concentration and subsequent erosion by peakcurrents. Mud pebbles and blocks were also formed by lateral migration of the channels thateroded adjacent muddy tidal flats and salt marshes.

Alternation of sand-rich and muddy IHS suggests periodical changes in the position of theturbidity maximum due to seasonal variation of fluvial discharge, in good agreement with theseasonal climate in Patagonia during the Late Miocene. Heterolithic bedding preservesneap-spring tidal cycles interrupted by periods of erosion occurred during spring tides orincreases in the fluvial discharge, and no sand deposition occurred during neap tides. IHS setsdipping in N-S opposite directions indicate recurrent migration of high sinuosity channels in thetightly meandering reach.

Grain size analyses of successive sand-mud layers in heterolithic bedding allow distinctionof a part of a tidal cycle. Layers of current-ripple laminated sands with bipolar palaeocurrentsdirections show a consistent asymmetry in mean grain size, with coarser grained west (flood)oriented layers and finer grained east (ebb) oriented ones. The east oriented layers tend todisappear during neap tides.

Repeated lateral migration of meandering channels caused erosion of the adjacentfreshwater, low-energy restricted environments, including a well preserved vertebrate faunaconcentrated in channel lags after short transport.

Dalrymple, R.W., Choi, K., 2007. Morphologic and facies trends through the fluvial–marine transition intide-dominated depositional systems: A schematic framework for environmental and sequence-stratigraphicinterpretation. Earth-Science Reviews 81, 135–174.Dozo, M.T., Bouza, P., Monti, A., Palazzesi, L., Barreda, V., Massaferro, G., Scasso, R.A, Tambussi, C.,2010. Late Miocene continental biota in Northeastern Patagonia (Península Valdés, Chubut, Argentina).Palaeogeography, Palaeoclimatology, Palaeoecology, 297: 100-106.Scasso, R., del Río, C.J., 1987. Ambientes de sedimentación y proveniencia de la secuencia marina delTerciario Superior de la región de Península Valdés. Revista de la Asociación Geológica Argentina 42(3/4), 291–321.Scasso, R., McArthur, J.M., del Río, C., Martínez, S., Thirlwall, M.F., 2001. 87Sr/86Sr Late Miocene age offossil molluscs in the “Entrerriense” of the Valdés Peninsula (Chubut, Argentina). Journal of SouthAmerican Earth Sciences 14, 319–329.van den Berg, J.H., Boersma, J.R., van Gelder, A., 2007. Diagnostic sedimentary structures of thefluvial-tidal transition zone – Evidence from deposits of the Rhine and Meuse. Netherlands Journal ofGeosciences — Geologie en Mijnbouw, 86: 287 – 306.

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THE VARIATION OF THE SEDIMENTARY FACIES ON JADEBUSEN TIDAL BASIN INGERMANY: SURFACE SEDIMENTS AND SEDIMENTARY STRUCTURES

Chang Soo SON*, Alexander BARTHOLOMAE**, Burghard W. FLEMMING**, Seong SooCHUN*, In Tae LEE***

*CHONNAM NATIONAL UNIVERSITY, 77 Yongbong-Ro, Buk-Gu, 500-757, Gwangju, Korea,[email protected]**SENCKENBERG, Suedstrand 40, 26382, Wilhelmshaven, Germany***RESEARCH INSTITUTE FOR COASTAL ENVIRONMENT AND FISHERY-POLICY, 77 Yongbong-Ro,Buk-Gu, 500-757, Gwangju, Korea, [email protected]

The study area is located at northwestern Germany. It is a broad inlet of the North Sea thatcovers an area of 190 km2. This area is characterized by semi-diurnal tides and the mean tidalrange is around 3.8 m. The prevailing wind direction is from west-southwest. The discharge of theRiver can be negligible due to the small amount of water.

For this study, 80 samples of surface sediments and 38 box- and pipe-cores were collectedalong four transects (Fig. 1).

In general, the distribution pattern of surface sediments in this area is shown in Fig. 1. Firstof all, sand facies are predominant in the eastern area (transect 1) except for the nearbyshoreline, whereas sand contents tend to decrease dramatically from the vicinity of the mainchannel to the landward direction in the southern and southwestern areas (transect 2 and 3). Inthe western area, on the other hand, the mud contents are high on average regardless ofsampling positions (transect 4).

In the case of sedimentary structures, cross-laminated sand, bioturbated sand andalternated sand/mud beds are prominent in the sand dominant areas, whereas homogeneousmud and bioturbated mud are predominant in the muddy area. In addition, the southwestern andwestern areas (transect 3 and 4) are characterized by the presence of coarse sand to gravel bedand shell bed except for the close to the shoreline.

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The distribution pattern of surface sediments on Jadebusen tidal basin.

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DO STROMATOLITES NEED TIDES TO TRAP OOIDS? INSIGHTS FROM THECOASTAL-LAKE CARBONATES OF THE LEZA FM (EARLY CRETACEOUS, N

SPAIN)

Pablo SUAREZ-GONZALEZ, I. Emma QUIJADA, M. Isabel BENITO, Ramón MAS

DPTO. ESTRATIGRAFIA, FACULTAD DE CIENCIAS GEOLOGICAS, UNIVERSIDAD COMPLUTENSEDE MADRID - IGEO (CSIC-UCM), José Antonio Nováis 12., 28040, Madrid, Spain,[email protected]

Stromatolites associated with ooid grainstones are often described in the literature, both inmarine and fresh-water environments. However, lateral relationship between them does notnecessary entail that ooids are trapped within the stromatolites. Interestingly, stromatolites thattrap ooids are quite rare. The Cretaceous Leza Fm (Barremian-Aptian in age, Cameros Basin, N.Spain) offers an exceptional opportunity to elucidate the factors controlling grain trapping. TheLeza Fm carbonates were deposited in coastal-lakes with several interrelated sedimentaryenvironments, including fresh-water facies and facies with clear marine influence, and it containstwo stromatolite types associated with ooids: one type traps grains (agglutinated ooliticstromatolites) and the other (skeletal stromatolites) does not.

Agglutinated oolitic stromatolites of the Leza Fm (Fig. 1A) occur at the top of rippled ooidgrainstone deposits, up to 1 m thick. Ooid grainstones are composed of ooids, peloids, intraclastsand bioclasts (ostracodes and foraminifera) and they show cm-scale lenticular, wavy and flaserbedding (Fig. 1C-D), which resemble some of the typical structures of peritidal carbonates. Theagglutinated oolitic stromatolites are composed of alternating oolitic layers (formed by trapping ofooids by microbial mats) and clotted-peloidal micritic layers (formed by microbially-inducedcarbonate precipitation) (Fig. 1B). Small calcified filaments, relicts of mat microbes, are very rare.These stromatolites are one of the oldest examples of agglutinated carbonate stromatolites andtheir oolitic layers are similar to those of present-day popular examples of Bahamas and SharkBay (Australia) (Reid et al., 1995). Nevertheless, the present-day agglutinated oolitic stromatolitesare formed mainly by one accretion mechanism (trapping of ooids) with hiatuses marked by thinmicritic crusts, but they do not significantly accrete by precipitating microbially-inducedclotted-peloidal or filamentous carbonate. The conditions for effectively trapping ooids in theserecent examples are soft and partially uncalcified surface mats, explained by the low carbonatesaturation state of the waters (Riding, 2011), and grains supply, explained by the movement ofooids over the stromatolites due to tidal currents (Dill et al., 1986). Shallow marine settings,generally showing tidal influence, have been proposed for the rare ancient examples of thesestromatolites (Riding et al., 1991; Matyskiewicz et al., 2006; Arenas & Pomar, 2010).

Skeletal stromatolites of the Leza Fm (Fig. 1E) occur in fresh-water lacustrine facies, wherethey are laterally related with sandstones and grainstones of intraclasts, oncoids, ooids andbioclasts (ostracodes and charophytes). The dominant microfabric of these examples is long andstrongly calcified microbial filaments with no trapped grains (Fig. 1F), thus their main accretionmechanism is active microbial mat calcification. Several examples of skeletal stromatolites andother stromatolite types are associated with ooid grainstones in ancient lacustrine sequences(e.g. Cole & Picard, 1978; Paul & Peryt, 2000), but, to our knowledge, none of them have trappedooids in their microfabrics.

The textural differences between the Leza Fm tidal-influenced agglutinated ooliticstromatolites (with soft and poorly calcified mats that trapped grains, Figs. 1A-B) and fresh-waterskeletal stromatolites (with hard and strongly calcified mats that did not trap grains, Figs. 1E-F),suggests that water chemistry and hydrodynamics during their formation were different. Carbonate saturation state of marine water might have been low enough to prevent intensemicrobial calcification in the tidal-influenced coastal-lakes, producing soft mats that trappedgrains. In addition, the cyclic hydrodynamic changes produced by tides allowed periodic supply ofgrains to be trapped by the soft mats, producing agglutinated ooid stromatolites. In contrast, thehigher carbonate saturation of meteoric waters, which came from the Jurassic carbonatesubstrate of the Cameros Basin, as well as the lower hydrodynamic changes of lacustrineenvironments, probably lead to the stronger mat calcification of skeletal stromatolites of the LezaFm and the absence of trapped grains.

Furthermore, input of meteoric water in the tidal-influenced coastal-lakes of the Leza Fmwould explain the differences between the present-day agglutinated oolitic stromatolites (formedmainly by trapping), and the Leza agglutinated examples (formed by alternation of trapping andmat calcification).

To conclude, we propose that water chemistry and hydrodynamics of tidal-influencedenvironments are very suitable for the development of agglutinated carbonate stromatolites,

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explaining why these stromatolites are almost restricted to tidal environments at the present-dayand in the geological record.

Field (A, C, D, E) and microscope (B, F) images of the Leza Fm stromatolites and associated facies. Seetext for descriptions.

Arenas, C. & Pomar, L. (2010) Palaeog., Palaeocl., Palaeoec., 297, 465-485.Cole, R. & Picard, M. (1978) Geological Society of America Bulletin, 89, 1441-1454.Dill, R.F.; Shinn, E.A.; Jones, A.T.; Kelly, K. & Steinen, R.P. (1986) Nature, 324, 55-58.Matyszkiewicz, J.; Krajewski, M. and Kedzierski, J. (2006) Facies, 52, 249-263.Paul, J. & Peryt, T.M. (2000) Palaeog., Palaeocl., Palaeoec., 161, 435-458.Reid, P.; Macintyre, I.; Browne, K.; Steneck, R. & Miller, T. (1995) Facies, 33, 1-18.Riding, R. (2011) In: Reitner & Thiel (eds.), Encyclopedia of Geobiology, 635-654.Riding, R.; Braga, J.C. & Martín, J.M. (1991) Sedimentary Geology, 71, 121-127.

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COASTAL MONITORING USING L-BAND SYNTHETIC APERTURE RADAR (SAR)IMAGE DATA IN THE MEKONG AND HUANGHE (YELLOW RIVER) DELTA AREAS

Akiko TANAKA

GSJ/AIST, Higashi, 305-8567, Tsukuba, Japan, [email protected]

Coastal geomorphology is highly variable as it is affected by sea-level changes and othernaturally- and human-induced fluctuations. To effectively assess and monitor geomorphologicalchanges in various time scales is thus critical for coastal management. Asian mega deltas arevulnerable to a sea-level rise due to its low-lying delta plain, and are dynamic region given a largeamount of sediment supply. However, limited data availability and accessibility in the deltas haveprevented establishment of systematic coastal monitoring. A variety of remote sensing systemscan be used to monitor geomorphological changes in coastal areas as it has wide spatialcoverage and high temporal repeatability. Especially, analysis using SAR (Synthetic ApertureRadar) data not affected by the cloud conditions offer potential for monitoring in the monsoonAsia region. In this paper, I present that L-band SAR data are useful for monitoring coastal areason a regional scale. I present two examples: ALOS (Advanced Land Observing Satellite) PALSAR(Phased Array type L-band SAR) data for the Mekong Delta area, and JERS-1 (Japanese EarthResource Satellite-1) SAR data for the Huanghe (Yellow River) Delta Areas.

ALOS/PALSAR data acquired over a period from December 2006 to January 2011 areanalyzed to investigate the relation between the sea level and the shape of mouthbars in theMekong River (Figure 1 (b)). River mouthbars with strong backscatter, which is surrounded by thewater with weak backscatter, are successfully extracted using a histogram thresholding algorithm.Estimated areas of river mouthbars, which are located openly faced to the South China Sea,gradually increase on an annual time scale (Figure 2). Besides this overall increasing trend,seasonal variations of areas are observed.

A series of binary image of JERS-1 data demonstrates the ability to monitor tidal flat in thehe Huanghe (Yellow River) Delta area quantitatively. Tidal flat area increased until 1995, and theneroded between 1995 and 1997. In May 1996, a new channel was cut near the tip of the delta,with the result that tidal flat area again increased. This area change is well correlated with annualwater and sediment discharge at the Lijin Station, which is located about 100 km upstream fromthe entrance of the mouth channel and the lowest hydrological station on the river. A series ofbinary data also captures the seasonal changes in tidal flat area.

To monitor the area changes over longer time intervals, further investigation combing datafrom another SAR and optical sensors is required. It will also be useful to apply to other regions toreach more comprehensive and comparable analysis.

Acknowledgement: Ministry of Economy, Trade and Industry (METI) and Japan AerospaceeXploration Agency (JAXA) retains the ownership of the original JERS-1/SAR andALOS/PALSAR data. This work is done in collaboration with Dr. Yoshiki Saito, Dr. Toru Tamura,Dr. Katsuto Uehara, Dr. Zuosheng Yang, Dr. Houjie Wang, Dr. Nguyen Van Lap, and Dr. Ta ThiKim Oanho.

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(a) Location map of the study area, (b) the Mekong River Delta in Vietnam, and (c) the Huanghe (YellowRiver) River Delta, in China. (b) Study area in the Mekong River Delta. Dashed boxes denote the

approximate area coverage of the acquired ALOS/PALSAR images with path-frame numbers. White lineboxes represent the target river mouthbars (RMs) used for area changes, superimposed on SAR intensityimage. (c) Study area in the Huanghe (Yellow River) River Delta, facing the Bohai Sea. Gray represents

land areas using SRTM 90 m digital elevation model data (Jarvis et al, 2008). Bold dashed and solid linesshow coastline and river from GSHHS, which is a high-resolution shoreline data set amalgamated from twodatabases in the public domain (Wessel and Smith, 1996). Rectangle indicates the target area. The target

area is located between the coastline and the low tide line. Figure 2 Temporal area changes in RM1(black), RM2 (blue), and RM3 (red) at the Mekong River Delta, with the linear least-square fit (dashed-line).

Circles, squares, crosses, and triangles show data from ascending tracks, Path-Frame 4770-0190 and4770-0180, and descending tracks, Path-Frame, 110-3420 and 110-3430, respectively. Symbols with gray

fill represent the area data without hourly tidal height data.

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SEDIMENTARY RECORDS OF CLIMATE CHANGES IN MACROTIDALTIDE-DOMINATED ESTUARIES

Bernadette TESSIER*, Isabelle BILLEAUD**, Philippe SORREL***

*UMR CNRS 6143 M2C, UNIVERSITE DE CAEN, 24 rue des Tilleuls, 14000, Caen, France,[email protected]**TOTAL EXPLORATION & PRODUCTION, CSTJF, Avenue Larribau, 64018, Pau, France,[email protected]***UMR CNRS 5125 PEPS, UNIVERSITE CLAUDE BERNARD–LYON 1, 27-43 bd du 11 Novembre,69622, Other, France, [email protected]

During the last few years, many studies dealing with the Holocene evolution oftide-dominated estuaries and embayments, pointed out the major role of rapid climate changeson the morphodynamics behaviour of such coastal systems (Chaumillon et al., 2010). Examplesinclude the Holocene sedimentary infill of incised valleys along the Atlantic and English Channelcoasts of France (Billeaud et al., 2009; Sorrel et al., 2009, Sorrel et al., 2010; Tessier et al.,2011).

The aim here is to propose a synthesis of the different features that can be ascribed toclimate changes during the sedimentary infill of macrotidal tide-dominated estuaries andembayments (Figure). This synthesis is based mainly on the data collected in theMont-Saint-Michel Bay (MSMB) and Seine estuary (SE) (NW France). The general context is thatof the mid- to late Holocene (since 7000 y. BP) and associated slow sea-level rise (1-2 mm/y),and that of the ~1500 year-periodicity rapid climate changes of the North Atlantic domain (RCC,Mayewski et al., 2004; or Bond’s cold events, Bond et al., 1997) characterized by enhanced stormperiods of a few hundred years. Available radiocarbon dating clearly demonstrates that thefollowing features described are contemporaneous of these periods (Billeaud et al., 2009; Sorrelet al., 2009).

Various depositional environments such as tidal flats and salt marshes, estuarine channelsand bars characterize tide-dominated systems. In some areas, upper tidal flats and salt marshesdevelop in tidal “lagoons” sheltered behind wave-dominated coastal barriers that construct alongthe edges of the tide-dominated domain.

Cores collected in the sandflats (MSMB), subtidal bottomsets of the estuarine bars (SE) andmarginal tidal channel area (SE), display typical tide-dominated facies successions, includingbadly sorted muddy sands and well-preserved mud-drapes (tidal beddings). Coarse-grainedshelly layers, decimetric in thickness, and with an erosive base, are regularly intercalated withinthese 5-6 m long successions. These layers that can be correlated at the scale of the wholestudied system (a few km) are interpreted as the result of storm-induced processes, andassociated with the periods of enhanced storminess. Tide-dominated successions that composethe infill of back-barrier tidal depressions (MSMB) display regular variations in grain-sizes; muddyand peaty facies are associated with a well-stabilized barrier, whereas, coarser sandy facies arerelated to a destabilized (or at least partly destroyed) barrier. In embayment (MSMB), whenbarriers are destroyed during the enhanced storm periods, the tidal prism suddenly increases dueto the inundation of the salt marsh areas located behind the barriers. This phenomenon ofenhanced tidal currents, due to enhanced storm activity, induces the formation of tidal creeks thatincise deeply mud flat successions. In the offshore approaches of these tide-dominatedenvironments (MSMB), subtidal sandbanks are composed of stacked tidal bodies, separated fromeach other by flat surfaces interpreted as the result of high energy erosional processes during theenhanced storm periods.

The preservation of these different signatures demonstrates that climate changes should beconsidered as major factors of morphodynamic behaviour and long-term evolution of macrotidaltide-dominated coastal environments. However, no signature related to climate change has beenfound into the successions that characterize the main axis of the estuaries, where intensereworking constantly occurs under the action of powerful tidal currents. The cut-and-fill faciespreserved at the base of the successions are probably good candidate that remains to explore fordeciphering climate change impacts into these environments. More surely, since annual cyclesare commonly preserved on the upper part of these successions (Tessier, 1998), impacts of veryhigh frequency climate changes on macrotidal tide-dominated estuaries can be potentiallystudied.

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Schematic representation of the sedimentary features preserved in Holocene incised-valley infills recordingthe impacts of enhanced storminess periods (~1500 year-periodicity Rapid Climate Change – RCC) onmacrotidal tide-dominated environments. Such features are preserved almost everywhere, except in the

active estuary, where however very high frequency (VHF) climate variability can potentially be deciphered(black scale bar indicative: 1 m)

BILLEAUD I., TESSIER B, LESUEUR. P (2009). – Impacts of Late Holocene rapid climate changes asrecorded in a macrotidal coastal setting (Mont-Saint-Michel Bay, France). Geology, 37, 1031-1034.BOND G., SHOWERS W., CHESEBY M., LOTTI R., ALMASI P., DE MONECAL P., PRIORE P., CULLENH., HAJDAS I., BONANI G. (1997). A pervasive millennial-scale cycle in north Atlantic Holocene and glacialclimates, Science, vol. 278, pp. 1257-1266.CHAUMILLON E., TESSIER B. & REYNAUD J.-Y. (2010). Stratigraphic records and variability of incisedvalleys and estuaries along French coasts. Bull. Soc. géol. France, 181, 2, 75-86.MAYEWSK P.A., ROHLING E.E., STAGER J.C., KARLÈN W., MAASCH K.A., MEEKER L.D., MEYERSONE.A., GASSE F., VAN KREVELD S., HOLMGREN K., LEE-THORP J., ROSQVIST G., RACK F.,STAUBWASSER M., SCHNEIDER R.R., STEIG E.J. (2004). Holocene climate variability, QuaternaryResearch, vol. 62, pp. 243-255.SORREL P., TESSIER B., DEMORY F., DELSINNE N., MOUAZÉ D. (2009). Evidence for millennial-scaleclimatic events in the sedimentary infilling of a macrotidal estuarine system, the Seine Estuary (NWFrance). Quaternary Science Reviews, 28, 499-516.SORREL P., TESSIER B., DEMORY F., BALTZER A., BOUAOUINA F., PROUST J.N., MENIER D.,TRAINI C. (2010) Sedimentary archives of the French Atlantic coast (inner Bay of Vilaine, south Brittany):depositional history and late Holocene climatic signals. Continental Shelf Research 30, 1250-1266.TESSIER B., 1998. Tidal cycles: annual versus semi-lunar records. In: Tidalites: Processes and Products.Eds.: Alexander, C., Davis Jr., R.A. & Henry, V.J. SEPM Special Publication n°61, 69-74TESSIER B., BILLEAUD I., SORREL P., DELSINNE N. & LESUEUR P. (2011) Infilling stratigraphy ofmacrotidal tide-dominated estuaries. Sedimentary Geology. doi:10.1016/j.sedgeo.2011.02.003

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MARINE HABITAT CLASSIFICATION: A PLURIDISCIPLINARY APPROACH IN AHIGH MACROTIDAL ENVIRONMENT. THE CASE OF THE ENGLISH MEDIAN

CHANNEL

Alain TRENTESAUX*, Romain ABRAHAM*, Alexandrine BAFFREAU**, Jean-Claude DAUVIN**,Sophie LOZACH**, Deny MALENGROS*, Emmanuel POIZOT***

*UMR CNRS 8217 GEOSYSTEMES, University Lille 1, 59655, Villeneuve D'Ascq, France,[email protected], [email protected]**UMR CNRS 6143 M2C, UNIVERSITE DE CAEN, 24 rue des Tilleuls, 14000, Caen, France,[email protected], [email protected]***GEOCEANO, Cnam/intechmer bp 324, 50110, Tourlaville, France, [email protected]

In megatidal sea, benthic marine communities are strongly dependent on the substrate,which is fashioned by hydrodynamism. This interdependence between substrate and benthiccommunities has enabled the establishment of marine benthic habitats classifications. Suchclassification allows depicting at the same time the general habitats diversity at the scale of agiven shelf, and the local variations at the scale of a smaller area. Indeed, it meets diverse needsfor ecological description of the marine environment such as general habitat knowledge orenvironmental impact assessment. The EUNIS classification is available to describe the mainhabitats of the European marine seabeds (Davies et al., 2004). Based on available data at thetime of its delivery, it is well adapted to describe shallow bays and estuarine environments, mostlycharacterised by mobile muddy fine sediments. On the contrary it fails in describing correctlyclean coarser sediments habitats in more deep areas such as those found in the central part ofEnglish Channel (La Manche) (Connor, 2005; James et al., 2007). This continental shelf seaconnects with the Atlantic Ocean in its western part and to the Southern North Sea in its easternpart. It is characterised by a series of strong offshore-inshore and capes/bays gradientscharacterised by progressive changes in temperature, bathymetry, shear stress that areregistered in the sediment, but also in the benthic communities.

In the framework of the European INTERREG IVa CHARM III project, supplementary datawere needed to increase knowledge in sublittoral coarse sediment habitats. To fulfil this objectiveand to re-assess EUNIS habitats types, the deepest (mid) part of the Western English Channelwas prospected. Our study is a snapshot of the habitats diversity thanks to two VideoCHARMsurveys in June 2010 and June 2011. We focussed on a longitudinal profile, from the westernapproach to the Greenwich meridian to stay in the deepest part of the English Channel (Figure 1).Nevertheless, no sediment was taken in the Hurd Deep, elongated depression in the medianChannel. Conversely, near coastal deep zone was sampled along the Brittany coast to investigatean inshore/offshore gradient (Figure 1). This approach could be compared to that of Cabioch etal. (1977). One big difference is that, despite the high quality of their study, it was a combinationof several surveys that were run during more than ten years in the 1960’ to the 1970’.VideoCHARM study is a synoptic work as sampling has been realised within two year and at thesame season. A multidisciplinary approach was used to better precise the different habitats. Bothindirect (Side scan sonar, ROV) and direct (Grab sampling with benthos determination, andgrain-size analyses) approaches were used and combined.

Different types of benthic habitats are defined. We observe a progressive change in theresidual tidal current speed and a progressive change in the habitat structure from the WesternApproaches to the East. The diversity is changing at the scale of a local study depending on thesediment type and the presence of pebbles or hard substrates, but also over the entire EnglishChannel. The substrates and sediment characteristics vary a lot, also at diverse scales (Figure 2).These changes will be discussed and compared with physical data such as shear stress orseawater temperatures.

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Comparison of different visual description of the sediment, by grab sampling or by video. Grab samplesshow the variability is sediment type in a small area on the sea bed (each picture is from a different

sampling site) and ROV images show heterogeneity of sedimentary profiles at the scale of one samplingstation (all images are from the same video). The top frame and the bottom frame show observations within

a same area, indicated on the map.

Cabioch, L., Gentil, F., Glaçon, R., et Retière, C., 1977. Le macrobenthos des fonds meubles de laManche: distribution générale et écologie. In : Biology of benthic organisms : 11th European symposium onmarine biology, Galway, Ireland, 115-128. Connor, D.W., 2005. EUNIS marine habitat classification: application, testing and improvement. MESH, pp.16Davies C. E., Moss, D., et Hill, M.O., 2004. EUNIS habitat classification revised 2004. 307 ppJames, J.W.C., Coggan, R.A., Blyth-Skyrme, V.J., Morando, A., Birchenough, S.N.R., Bee, E., Limpenny,D.S., Verling, E., Vanstaen, K., Pearce, B., Johnston, C.M., Rocks, K.F., Philpott, S. et Rees, H.L., 2007.The eastern English Channel map. Science Series Technical Report n°139, CEFAS, lowestoft, 191 pp.

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DEVELOPMENT OF A SEABED MODEL FOR ANALYZING SEDIMENT ANDMORPHODYNAMIC PROCESSES IN THE GERMAN BIGHT (NORTH SEA)

Jennifer VALERIUS*, Peter MILBRADT**, Michael VAN ZOEST**, Manfred ZEILER*

*FEDERAL MARITIME AND HYDROGRAPHIC AGENCY, Bernhard-Nocht-str. 78, 20359, Hamburg,Germany, [email protected], [email protected]**SMILE CONSULT GMBH, Vahrenwalder Straße 4, 30165, Hanover, Germany, [email protected],[email protected]

MotivationAn increase in human activities in shelf and coastal waters as well as rising sea level due to

climate change reveals the need for better understanding nature and variability of the seabed.Especially the combination of marine geological field work and numeric modelling helps toimprove our knowledge and prediction capabilities with respect to sediment and morphodynamicprocesses.

The AufMod project funded by the Federal Ministry of Research and Education (BMBF) isfocussing on this interdisciplinary approach to develop tools and models for analyzing thelong-term morphodynamics in the German Bight (North Sea).

One objective is to build up a Seabed Model based on bathymetric and sedimentologicdatasets in space and time. The Seabed Model consists of a quasi-consistent and plausiblegeodatabase for bathymetric data and sedimentological parameters like grain size distributions,porosity, thickness of the mobile sediment (sand) layer and bedforms.

This geodatabase may be used as (1) a source of input data for numeric modelling and (2)for data-based analyses of morphological changes and sedimentological variations.

MethodologyIn the first stage of the project, point datasets available for the different parameters were

collected and stored in a database system called Functional Seabed Model, which includessophisticated interpolation and approximation methods for data-based modelling in time andspace. In the second stage of the project data-based modelling was applied to regular or irregulargrids in variable spatial resolution; confidence layers will be provided for each product.

Results and ProductsThe amount of data differs strongly among the parameters stored in the Functional Seabed

Model. Nearshore bathymetric data are available in an acceptable to relatively high spatialresolution from 1948 until today. Beyond a water depth of 15 m, bathymetric data in time arescarce as well as sedimentological parameters.

Based on these consistent bathymetric time series, morphological parameters like changesin depth (dz/dt) or „morphological space“ (zmax – zmin) can be derived or volumetric calculationscan be performed. Figure 1 illustrates the morphological space for the coastal and nearshorewaters of the German Bight.

Statistical parameters were calculated for the German Bight based on consistentsedimentological datasets. Figure 2 shows the distribution of the median (D50) in the GermanBight depicting areas of reworked (coarse) sediment (red colours) and areas of grain sizefractionation (green colours).

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Fig. 1: Morphological Space (zmax - zmin) in the German Bight from the coastline to the 20m-isobath for aperiod of 15 years (1996 to 2011) on a 50m-raster. Fig. 2: Interpolated d50-value in the German Bight in

half Phi intervals on an irregular grid.

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TIDAL ASYMMETRY: THE USE OF ARTIFICIAL RADIONUCLIDES IN SEDIMENTS(THE SEINE ESTUARY, FRANCE)

Anne VREL*, Dominique BOUST**, Patrick LESUEUR*, Catherine COSSONNET***, JulienDELOFFRE****, Carole DUBRULLE-BRUNAUD*, Nicolas MASSEI****, Marianne ROZET**, Luc

SOLIER**, Sandrine THOMAS***

*UMR CNRS 6143 M2C, UNIVERSITE DE CAEN, 24 rue des Tilleuls, 14000, Caen, France,[email protected], [email protected]**IRSN - LABORATOIRE DE RADIOECOLOGIE DE CHERBOURG-OCTEVILLE, Rue max pol Fouchet,50130, Cherbourg, France***IRSN - LABORATOIRE DE MESURE DE LA RADIOACTIVITE DANS L’ENVIRONNEMENT, Bois desRames, 91400, Orsay, France****UMR CNRS 6143 M2C, UNIVERSITE DE ROUEN , Place Emile Blondel, 76821, Mont Saint Aignan,France

The Seine estuary is the outlet of the catchment area of the Paris Basin, where finesediments and a number of anthropogenic elements and substances end in. Among them,artificial radionuclides can be used as tracers of sediment sources and mixing processes. Theymay originate from upstream (atmospheric fallout from Chernobyl accident in 1986 and fromnuclear weapons testing in the 1960s, licensed discharges from nuclear facilities...) or fromdownstream (La Hague reprocessing plant –Central Channel).

In this macrotidal estuary, trapping and upstream migration of sediment is in process, due tothe tide asymmetry; it is named “tidal pumping”. It has been previously documented using 60Co, ashort-lived radionuclide, originating from the La Hague reprocessing plant (north of Cotentinpeninsula). The average upstream velocity of 60Co-labelled sediment particles has beenestimated to be in the order of 10 km per year. The plutonium 239, 240 and the americium 241have much longer decay period and could, therefore, give the opportunity to better understandthe dynamics of the “tidal pumping” on a longer term.

Plutonium and americium profiles have been obtained in three sediment cores collected invarious settings along the lower Seine: (1) a proximal fluvial floodplain upstream from the estuary(i.e. without any tidal influence); (2) an old sheltered dock in the upper estuary (under moderatetidal influence); (3) a mudflat at the mouth (under strong tide and wave forcings). The sedimentscored were analysed and dated using historical data (bathymetric maps, flood time-series...),analysis of cesium 137, and signal processing techniques.

The inputs of Pu- and Am-bearing particles are characterized by contrasting ratios (239,240Pu/241Am). At the most upstream (fluvial) cored site, the sediments are marked by the globalfallout with a ratio about 2.5. In the upper estuary, a combined influence of upstream soliddischarges with sediment particles coming from downstream (since 1975) is observed. Thesediment pool coming from downstream, marked by discharges from La Hague reprocessingplant, is characterized by a much lower ratio about 1.0. The input signal of marine Pu- andAm-bearing particles is constrained by the Pu and Am data obtained in the sediments cored atthe mouth of the estuary (Figure 1).

Thanks to a simple mixing model, it is possible to quantify the percentage of radionuclidesfrom upstream for each year and to obtain a time-series of the percentage of radionuclides in theupper estuary due to “tidal pumping”. The radionuclides downstream contribution in the upperestuary is low or nonexistent depending on the year (0 to 4%). The “tidal pumping” is dependenton a lot of parameters during several consecutive years: hydrological parameters and tidalparameters. Overall, “tidal pumping” is amplified when the flow is low and the tide energy is highduring the 10 previous years.

Artificial radionuclides are likely to be powerful tracers for the understanding of fine-grainedsediment dynamics in macrotidal estuaries. Moreover, they lead to unique and valuableinformation on the dynamics of the “tidal pumping” over the last 20 years.

127


Upstream and downstream inputs of artificial radionuclides in the Seine estuary

Boust, D., Lesueur, P., Rozet, M., Solier, L., Ficht, A., 2002. The dynamics of Co- labelled sédimentparticles in the Seine estuary. Radioprotection 37, 749-754.

128


HYDROLOGIC CHARACTERISTICS OF THE YELLOW RIVER MOUTH, CHINA

Dong WANG*, Shengli SONG*, Hao DING*, Jichun WU*, Qingping ZHU**, Ling WANG***

*SCHOOL OF EARTH SCIENCES AND ENGINEERING, Nanjing University, 210093, Nanjing, China,[email protected]**CHINA WATER INTERNATIONAL ENGINEERING CONSULTING CO, LTD., China Water InternationalEngineering Consulting co, Ltd., 100010, Beijing, China***HYDROLOGY BUREAU , the Yellow River Conservancy Committee, 450000, Zhengzhou, China

In recent years, the impact of climate change and human activities on the World‘s LargeRivers’ runoff is great, especially on that of the Yellow River. Using 1950-2003 runoff series fromLijin hydrologic station of the Yellow River Mouth as the case, the eigenvalues (maximum value,minimum value, mean value, skewness coefficient Cv ,Variation coefficient Cs , etc.) arecalculated. And the main periods characteristics of monthly runoff series are ascertained by usingWA (Wavelet Analysis) method. Then taking these eigenvalues and the main period’scharacteristics of monthly runoff series as the input vector of the SOM (Self-Organizing Maps)method, a WA-SOM coupling model is established in this study. Thus the characteristics ofmonthly and annual runoff series of 2 spans (1950-1969 and 1970-2003 respectively) of theYellow River Mouth are compared. Results show that: (1) After 1970s, the monthly and annualrunoff series decreased significantly in the lower Yellow River. (2) The main periodscharacteristics of monthly runoff after 1970s became more complex than before 1970s. (3) After1970s, the change of runoff series in January and February is not obvious, but the changes ofrunoff series in the other months are significant.

129


The continuous wavelet transform result of observed annual runoff series in Lijing station of the YellowRiver (1-30a)

130


SEDIMENT RESUSPENSION, FLOCCULATION AND SETTLING IN A MACROTIDALESTUARINE ENVIRONMENT

Ya Ping WANG

SCHOOL OF GEOGRAPHIC AND OCEANOGRAPHIC SCIENCES, 22 Hankou Road, 210093, Nanjing,China, [email protected]

Flocculation, settling and resuspension play important roles on the cohesive sedimenttransport and biogeochemical processes in the estuarine environment. Results from in-situmeasurements of hydrodynamics, sediment resuspension and sediment particle size distributionfrom both the bentic boundary layer and the whole water column are used to examine thesediment resuspension and sediment aggregation process in the Jiulong River estuary (China).Time-series from two experimental periods were phased averaged into typical neap and springtidal cycles and the tidal variability of the processes is discussed.

Near bed flow data were used to provide accurate estimates of bottom shear velocities andassociated turbulence parameters. The law of the wall, Reynolds stress and the inertialdissipation methods were utilized. The latter two methods were found to be more reliable in thisenvironment while the law of the wall failed to provide reliable estimates during slack waterconditions. On the basis of these results a drag coefficient of approximately 4.2x10-3 wasestimated to be valid in this area without a significant difference between ebb and flood stages.Sediment resuspension is higher during spring tides in response to higher velocities. Duringresuspension, flocullation processes were revealed. The primary particles identified through theanalysis of dispersed sediment from water samples had a mean size of just under 10microns.Bottom sediments were found to be either unimodal with a mean size of approximately 200microns or bimodal with peaks corresponding to 200microns and to the mean size obtained fromthe water samples. In situ size distributions obtained using the LISST show a variable sedimentsize concentration in the water column that is influenced by flocculation processes.

The size of the flocullates seems to be controlled by turbulence more than any otherparameter,

The flocculation exists widely during tidal cycles in the estuary, with in-situ mean sizesignificantly coarser one order more than the primary size of sampling particles. In addition, theturbulence dissipation is found to be negative related to the floc size and positive related to thesettling velocity, which controls the aggregation and deflocculation processes. The 95-percentilefloc size, which was close to the maximum floc size, had a significant linear relationship withKolmogorov microscale, while the former was 0.3-0.5 size of the later. It indicated that floc sizevariations are limited by the turbulent eddy evolution during a tidal cycle. Further, the highturbulence dissipation parameter, corresponding to high bottom shear velocities, is attributed tothe entrainment and resuspension of bottom sediment with high densities into the water columnand results in high effective density of SPM and high settling velocity. In addition, the highturbulence dissipation parameter is associated with small eddies and could destroy the macrofloc.Such a condition is present at the middle flood/ebb, especially during the spring stage. On thecontrary, the sea water becomes strong stratification at low water level when the river dischargeenhances and the low salinity or salt wedge dominated, and then the turbulence was suppressedwith low dissipation. This induces large Kolmogorov microscale (or big eddy) and thus isadvantage of macrofloc formation.

131


Study area showing the tripod station

132

EFFECTS OF GRAIN-SIZE SORTING ON THE SCALE-DEPENDENCES OFEQUILIBRIUM MORPHOLOGY OF BACKBARRIER TIDAL BASINS

Yunwei WANG, Qian YU, Shu GAO

MOE KEY LABORATORY OF COAST AND ISLAND DEVELOPMENT, 22 Hankou Road, NanjingUniversity, 210093, Nanjing, China, [email protected]

Coastal tidal basins consist of two major morphological units: tidal channels and tidal flats.Based on field observations of the backbarrier tidal basins along the Dutch-German North Seacoast, some empirical relations were found between the morphological parameters and the basinscale: the dimensional parameters of channel area (Ac) and volume (Vc) are proportional to the1.5 power of the basin area (Ab) and tidal prism (P), respectively; and the dimensionlessparameters of relative channel area (Ac/Ab) and the ratio of channel volume to tidal prism (Vc/P)are both proportional to the square root of basin area (Ab1/2). The coefficients in the power-lawexpressions are all in the order of 10-5. Furthermore, previous observations also indicated that, atequilibrium states, both volume and area hypsometries of back-barrier tidal flats are dependenton the basin scale. Large basins favour pronounced concave hypsometries, while small basinsfavour subdued concave ones. In this study, the scale-dependences of equilibrium morphology ofthe Dutch-German tidal basins are investigated by process-based modeling approaches on thebasis of the Delft3D system with single and multi-grain-size fractions of sediments, so as toprovide physical explanations for the scaling relations. The effects of grain-size sorting on thescale-dependences of equilibrium morphology are therefore emphasized through comparisons ofthe results from the single fraction modeling, multi-fraction modeling and observations.

The model results suggest that both the single and multi-fraction modeling series show thesame types of the power-law scaling relations as the empirical expressions derived fromobservations, and the values of the coefficients in the equations are also close. However, thedifferences of the flat hypsometries in the single and multi-fraction modeling series arepronounced, and for the equilibrium flat hypsometries, the multi-fraction modeling has a betterperformance than the single-fraction cases, since the coefficients in the scaling relations arecloser to those derived from the observed data.

The local balance processes in channels is proposed as interpretations. Due to limitedremote sediment supply, the channel-flat morphology is generated from the redistribution of thelocal sediments in the basins. When multi-grain-size fractions are employed, the channel tends tobe sculptured by the scouring of the fine grains. The fine sediments, on one hand, are more easilyeroded, leading to more occurrences of the shallow channels. On the other hand, the laggedcoarse sediments may prevent erosions, the deep channels thus become shallower. Therefore,the deeper shallow channels and the shallower deep channels result in limited changes of themorphological parameters about channels. However, the grain-size sorting effects on the tidalflats are more pronounced due to the lack of these balance processes. The pronounceddifferences in the flat hypsometry suggest the importance of grain-size sorting on the flatmorphology. Through this effect, fine sediments deposit on the high flat, and coarse sedimentsaccumulate on the low flat, resulting in the significant modifications to the flat morphology.

133

a: initial bathymetry and grid of the reference case; b and c: bathymetry of the reference case after a60-year simulation period from the single and multi- fraction modeling, respectively (The color bar denotes

the bed elevation relative to mean sea level (m))

134


INTERNAL ARCHITECTURE AND EVOLUTION OF BIOCLASTIC BEACH RIDGES INA MEGATIDAL CHENIER PLAIN: WAVE FLUME EXPERIMENTS AND FIELD DATA

Pierre WEILL*, Dominique MOUAZE**, Bernadette TESSIER**

*MINES PARISTECH, CENTRE DE GEOSCIENCES, 35 rue Saint-Honoré, 77300, Fontainebleau, France,[email protected]**UMR CNRS 6143 M2C, UNIVERSITE DE CAEN, 24 rue des Tilleuls, 14000, Caen, France,[email protected], [email protected]

Forcing parameters of chenier ridges formation and internal structure are investigated usingfield data and wave flume experiments. This work focuses on modern, coarse bioclastic beachridges such as those located on the uppermost part of the tidal flat in Mt. St. Michel Bay (NWFrance), in the context of a prograding megatidal chenier plain. These ridges migrate landwardover the upper tidal flat and salt marshes by washover processes during coincidence of highspring tide and enhanced wave activity, until they are stabilized and integrated in the chenierplain.

The internal architecture of these ridges has been investigated on the field usinghigh-frequency ground-penetrating radar (GPR). Three types of ridges were identified, thatrepresent a continuum of evolution between active transgressive, mature transgressive (Fig. 1),and mature progradational ridges (Fig. 2). Each type reflects major differences in externalmorphology and internal structure. The altitude of the banks regarding to the level of tidalflooding, as well as local sediment supply, are assumed to be important forcing parameters inchenier development and evolution.

In order to investigate the role of low frequency fluctuations of the level of tidal flooding,wave flume experiments were carried out with natural sediment sampled on the field. Despitedifferences of spatial and time scales, the experimental models compare very well with themorphologies and internal structures observed on the field (Fig. 1 and 2). The three stagesidentified on GPR profiles have been successfully modelled. Flume experiments confirmed thatthe flat shape of bioclastic particles plays an essential role in sediment sorting in the wavebreaking zone, and bedding deposition on the beachface or in washover fans. On longer timescales, the water level appears to be the key parameter controlling the patterns of washovergeometries. Moreover, low water levels allow sediment to accumulate off the chenier. Duringsubsequent water level rise, this sediment is available for the deposition of a new washover unit,or for a new stage of chenier progradation, depending on the altitude of the ridge. This resulthighlights the role of multi-annual to multi-decennial tidal cycles in chenier construction.

Both field work and flume experiment results ties up with the conclusion that low frequencymean water level fluctuations control the dynamics and the evolution of chenier ridges, andconsequently their internal architecture. On the field, low frequency mean water level fluctuationsare related to the 4 and 18 years tidal cycles, which should thus be regarded as the main factor ofchenier coast evolution at this time scale in such macrotidal environments.

135


Comparison between flume experiment results (A) and GPR profile (B) and interpretation (C). The differentcolours emphasize the similarities between the different morpho-sedimentary units. HSTL = High Spring

Tidal Level.

136


THE LATE PLEISTOCENE–HOLOCENE STRATIGRAPHY AND SEDIMENTARYENVIRONMENT OF THE TIDAL RADIAL SAND RIDGE SYSTEM, JIANGSU

OFFSHORE, SOUTH YELLOW SEA

Yong YIN

THE KEY LABORATORY OF COAST AND ISLAND DEVELOPMENT, Hankou rd. 22, 210093, Nanjing,China, [email protected]

The South Yellow Sea is a shallow and semi-closed, epicontinetal sea between the Koreanpeninsula and China, with average water depth of 46m. The western coast of South Yellow Seawithin Jiangsu province has a length of 888.9 km and mostly dominated by tidal flat. On theaverage, it has a slope less than 1/1000 and a width between 4 and 5 km. But the widest tidal flatcan reach to 14 km. On offshore area, a characteristic tidal radial sand ridge system (TRSRS),radiating perpendicularly or at a high angle to the coastline, has developed under a complex tidalcurrent field along the west coast of South Yellow Sea between the Yangtze River delta to thesouth and the abandoned Yellow River delta to the north. This ridge system has a length of199.6km in latitude and 140 km in longitude, which covers an area of 22470km2. It contains morethan 70 ridges and tidal channels between them. The ridge system which overlies the latePleistocene terrestrial and marine deposits has formed during Holocene period. The latePleistocene terrestrial deposits are mostly contributed by the Yangtze and Yellow River (the twobiggest rivers in China) when they flowed into the sea in the study area. There remains lot ofuncertainties about the evolution of sedimentary environments and the source materials whetherthey are derived from Yangtze or Yellow River. This paper is based on 12 cores and somechronological control obtained in 2007 and 2011. We try to set up the stratigraphic framework andsedimentary sequence based on sedimentary facies and core correlation between. We also try todistinguish the source of deposits from clay mineral ratio from cores.

12 cores, some from sandy ridges and some from tidal channels have been drilled to revealthe late Pleistocene–Holocene sedimentary environment of the system. Seven facies have beendistinguished (fig.1): (1) Fluvial. This facies usually appears on the core bottom. It consists offining-upward successions of poorly sorted fine to medium sands, with fine pebbles. Ripple crossand horizontal-beddings are common. No foraminifera, but fresh water snails are present.Calcareous concretion probably containing ferric oxide can be found in the facies. These depositsare probably from the point bar. In core 07SR11, the overbank deposits have been foundsuperimposed on the point bar, which are composed of olive grey to greyish brown silty clay toclay, with lenticular beddings and horizontal laminas. Climbing-ripple laminations are common inthe facies. (2) Tidal flat. This facies appears immediately beneath and above the so called stiffclay. It consists of light olive grey silt, interlayered with dark yellowish brown silty clay. Flaser,wavy and lenticular beddings, with bidirectional laminations are common. Foraminifera speciesare mostly benthic communities, indicating littoral to neritic environment. (3) Estuary to Neritic.This facies consists of olive black clay with silty layers, interlayered with poorly sorted light olivegrey silt, with lenticular and wavy beddings and few bioturbation. Foraminifera species are similarto tidal flat. (4) tidal-controlled coast to inner shelf. This environment includes sandy ridge andassociated tidal channels. The tidal ridge is characterized by massive sand and sand-dominatedcouplets such as flaser beddings. The muddy pebbles are common in this facies. Tidal channelconsists of light olive grey silt and muddy silt, with wavy beddings. Bidirectional cross beddingsand contorted beddings are common. (5)Stiff mud (paleosol). This facies is composed of yellowbrown clay and silty clay. The stiff mud contains abundant pedogenesis features, such asargillans, ferric mottles, concretions and plant roots, but lacks marine microfossils. The stiff mudwas produced in a complex terrestrial environment from fluvial overbank to swampy andlacustrine plain. It is distinct from overlying strata in lithological characteristics and microfossilassemblages with sharp contact. 14C dating indicated that stiff mud was formed during 15-25 kaB.P. (Li et al., 2001).

The scenario shows that during the MIS 4, the cut down of incised valley took place in studyarea due to the sea level decline. With the sea level rise during the MIS 3, the incised valley hasbeen filled with fluvial and tidal flat deposits successively. It experienced extensive exposureduring the LGM and produced the symbolized stiff mud (paleosol). The study area was drownedduring the Holocene transgression and received tidal flat deposits at the first period of sea levelrise and then estuary to neritic deposits during Mid-Holocene. In late Holocene, the study areachanged to a tidal-controlled coast to inner shelf. The sediments have been reworked by strongtides to build up sandy ridges and channels between them.

137


The stratigraphic correlation between cores in study area

Li, C.X, Zhang, J. Q.,Fan D. D. et. al.,2001. Holocene regression and the tidal radial sand ridge systemformation in the Jiangsu coastal zone, east China. Marine Geology, 173:97-120

138


MODELING THE FORMATION OF A SAND BAR WITHIN A LARGEFUNNEL-SHAPED, TIDE-DOMINATED ESTUARY: QIANTANGJIANG ESTUARY,

CHINA

Qian YU

MOE KEY LABORATORY OF COAST AND ISLAND DEVELOPMENT, 22 Hankou Road, NanjingUniversity, 210093, Nanjing, China, [email protected]

The Qiangtangjiang Estuary (the outer part being known as Hangzhou Bay) located on theeast coast of China is a large funnel-shaped, tide-dominated and well-mixed estuary. Theequilibrium estuarine morphology has been attained and characterized by a large sand bar havinga total length of 125 km and an elevation of 10 m above the average adjacent seabed. In order toinvestigate the physical processes governing the formation of this morphological feature,two-dimensional depth-averaged process-based morphodynamic modeling (Delft3D) was carriedout on a schematized funnel-shaped domain with exponentially decreasing widths based on thedimensions of the Qiangtangjiang Estuary. The model simulated a 6,000-year period, the outputshowing the development of a sand bar that reached equilibrium within about 3,000 years. Thegeneral shape, size and position of the modeled sand bar are consistent with the observations.Short-term simulations of hydrodynamic and sediment transport processes at the initial stageindicate that, in response to the interactions between river discharge and tidal currents, which arestrongly influenced by the funnel-shape, the sand bar developed in the transition zone betweenthe river-dominated upper estuary and the flood-dominated lower estuary where sedimenttransport pathways converge. A series of sensitivity analyses suggest that the estuarineconvergence rate, sediment grain size, and river discharge are the main controlling factors ofsand bar formation. Similar to other large funnel-shaped, tide-dominated estuaries of the world, asufficient supply of fine cohesionless sediment (derived from the adjacent Changjiang Estuary), alarge river discharge, and a strong shoreline convergence rate have shaped the large sand bar inthe Qiangtangjiang Estuary.

139


Modelled long-term evolution of the longitudinal bed morphology of Qiangtangjiang estuary, and themodelled final (6000 yr) equilibrium lateral averaged bed and the large sand bar.

140


THE VARIATIONS OF SALINITY AND STRATIFICATION FOR MICRO-TIDAL ANDMANGROVE-COVERED FROG CREEK SYSTEMS, FLORIDA

Jicai ZHANG*, Joseph HUGHES**, Ping WANG***, Mark HORWITZ***

*MOE KEY LABORATORY OF COAST AND ISLAND DEVELOPMENT, 22 Hankou Road, NanjingUniversity, 210093, Nanjing, China, [email protected]**U.S. GEOLOGICAL SURVEY, Florida Water Science Center, 33612, Tampa, United states,[email protected]***COASTAL RESEARCH LABORATORY, DEPARTMENT OF GEOLOGY, Department of Geology,University of South Florida, 33620, Tampa, United states, [email protected], [email protected]

The variations of salinity and stratification for Terra Ceia River and Frog Creek (Frog Creeksystems), Florida, which were mangrove covered, micro-tidal, partially mixed and shallowestuaries, were discussed based on one-year observations. Temperature, salinity and tidalfluctuation were all important physical factors that influence the size and extent of mangroveswamps. The level of stratification in the water column was crucial in controlling the intensity ofvertical mixing and hence, the vertical flux of water properties. The circulation of Frog Creeksystems was driven by weak tidal dynamics and small river discharge, which can be asupplement to the studies of estuarine hydrodynamics. Salinity observations indicated that thesaline water can persistently affect upstream areas of Frog Creek systems and the reason wasattributed to the bathymetry of river channel. The results of spectral analysis also proved that thebathemetry can significantly influence the temporal structure of salinity. The effects of periodicaltidal shears and river freshwater discharge on the stratification were investigated. Well mixedconditions were observed during flood tide and stratified conditions during ebb tide. Besides, wefound that the stratification can be enhanced by higher river discharge, while the stratificationwould be destroyed above a threshold river discharge. The threshold river discharge value wasdescribed qualitatively by: (1) processing the salinity time series with a low pass filter to eliminatethe diurnal, semidiural and other high-frequency tidal signals; (2) calculating the filtered (i.e.,subtidal) stratification as the difference between the bottom and the surface subtidal salinities; (3)rearranging the filtered stratification data according to the time of corresponding river discharge.

Example from Frog Creek Systems, Florida. The 100 pairs of average stratification versusexceedence probability (p) at four stations are shown in Fig. 1. The clearest relation ofstratification and p is observed at TF3 as shown in Fig. 1a. When the exceedence probability isless than 10%, the stratification is 1 or less. When p exceeds 10%, the stratification increases tovalues as high as 12. When p is approximately 20%, the stratification is sharply reduced to about6. Above a p of 20%, the stratification shows an approximately linear decrease from 6 to 2 withincreasing p. A similar response is also observed at TF2 as shown in Fig. 1b. However, the trendsare not very clear at TF1 or Manatee River where stratification would also be influenced byperiodical tidal variations (Figs. 1c and 1d).

141


Stratification versus the exceedence probability at TF3 (a), TF2 (b), TF1(c) and Manatee River (d). Reddotted lines indicate the trend of variations.

142


143


LIST OF AUTHORS

144


AABOUESSA Ashour: p. 99, 101ABRAHAM Romain: p. 85, 91, 123ALVAREZ Luis G.: p. 1ANDERSEN Thorbjørn Joest: p. 47, 69ANDRE Jean-Pierre: p. 107ARAI Shota: p. 87ARCHER Allen: p. 3

BBAFFREAU Alexandrine: p. 85, 123BANDEIRA Salomao: p. 93BARRIOS Edixon Jose: p. 5BARTHOLDY Jesper: p. 7BARTHOLOMAE Alexander: p. 9, 115BAUCON Andrea: p. 11, 13BENITO M. Isabel: p. 35, 103, 117BERTEL F: p. 75BERYOUNI Khadija: p. 31BESSON David: p. 29BILLEAUD Isabelle: p. 121BILLY Julie: p. 21BLANPAIN Olivier: p. 41BOUST Dominique: p. 127BOUZA Pablo: p. 113BREILH Jean-François: p. 21BURCHARD Hans: p. 45

CCAI Guofu: p. 39CHAMIZO BORREGUERO M.: p. 15CHANG Taesoo: p. 17, 19CHAUMILLON Eric: p. 21CHEN Wayne, C.: p. 81CHIARELLA Domenico: p. 83CHOI Kyungsik: p. 23, 25, 27CHUN Seong Soo: p. 115CLIQUET Dominique: p. 67COSSONNET Catherine: p. 127CUITIÑO José Ignacio: p. 113CUVILLIEZ Antoine: p. 79

DDALRYMPLE Robert W.: p. 29, 65, 73, 95,105, 107DAUVIN Jean-Claude: p. 31, 85, 123DE BOER Poppe: p. 15, 33DELCAILLAU Bernard: p. 67DELOFFRE Julien: p. 79, 127DIAZ-MOLINA Margarita: p. 35DIEZ-CANSECO Davinia: p. 35DING Hao: p. 129DOZO Teresa: p. 113DUBRULLE-BRUNAUD Carole: p. 127DUGUE Olivier: p. 67DURINGER Philippe: p. 99, 101

EEKWENYE Ogechi: p. 37EL-BARKOOKY Ahmed: p. 77ERNSTSEN Verner B.: p. 7ESIRTGEN Tolga: p. 63

FFAN Daidu: p. 39FELLETTI Fabrizio: p. 11, 13FENIES Hugues: p. 21FERRANDINI Jean: p. 107FERRANDINI Michelle: p. 107FERRET Yann: p. 41FLEMMING Burghard W.: p. 43, 115FLINT Stephen: p. 55FLOESER Goetz: p. 45FOREY Estelle: p. 75FRITIER Nicolas: p. 79FRUERGAARD Mikkel: p. 47FURGEROT Lucille: p. 49

GGAO Shu: p. 133GARLAN Thierry: p. 41GHIENNE Jean-François: p. 99GLUARD Lucile: p. 51GONG Wenping: p. 53GUGLIOTTA Marcello: p. 55

HHAMPSON Gary: p. 77HAQUIN Sylvain: p. 49HERRLING Gerald: p. 57HODGSON David: p. 55HOLLER Peter: p. 9HONG Chang Min: p. 27HORWITZ Mark: p. 141HUGHES Joseph: p. 141HUSTELI Berit: p. 59

IICHASO Aitor: p. 73, 105ILGAR Ayhan: p. 61, 63ITO Takashi: p. 87

JJABLONSKI Bryce: p. 65JACKSON Christopher: p. 77JACKSON Matthew: p. 77JAMES Noel: p. 29, 107JAMET Guillaume: p. 67JENSEN Maria: p. 59JO Joo Hee: p. 25JOHANNESSEN Peter N.: p. 47, 69JOHNSON Howard: p. 77JUNG Jae Hoon: p. 25, 27

KKALIN Otto: p. 35KARAKUS Erhan: p. 61, 63KAYA Serap: p. 61KIM Jincheol: p. 17KITAZAWA Toshiyuki: p. 71KURCINKA Colleen: p. 73

LLAFITE Robert: p. 41, 75, 79LANGLOIS Estelle: p. 75LE BOT Sophie: p. 41, 75


LEE In Tae: p. 115LEGLER Berit: p. 77LEMOINE Maxence: p. 79LESOURD Sandric: p. 79LESUEUR Patrick: p. 79, 127LEVA LOPEZ Julio: p. 109LEVOY Franck: p. 51LIU James T.: p. 81LONGHITANO Sergio: p. 83LOZACH Sophie: p. 31, 85, 123

MMACKAY Duncan: p. 105MAKINO Yasuhiko: p. 87, 89MALENGROS Deny: p. 85, 123MARGOTTA José: p. 91MAS Ramón: p. 103, 117MASSART Benoit: p. 77MASSEI Nicolas: p. 79, 127MASSUANGANHE Elidio: p. 93MEAR Yann: p. 31MEIRLAND Antoine: p. 75MELENDEZ N.: p. 15MICHAUD Kain: p. 95MILBRADT Peter: p. 125MOUAZE Dominique: p. 49, 135MURAT Anne: p. 31MØLLER Ingelise: p. 69

NNANAYAMA Futoshi: p. 87NICHOLS Gary: p. 37NIELSEN Lars Henrik: p. 47, 69, 69NWAJIDE Sunny: p. 37

OOBI Gordian: p. 37OH Chung Rok: p. 27OLARIU Cornel: p. 23, 109OLAUSSEN Snorre: p. 59

PPARIZE Olivier: p. 29, 107PARK Soo Chul: p. 97PEJRUP Morten: p. 47, 69PELLETIER Jonathan: p. 99, 101PEREZ Laurent: p. 49POIZOT Emmanuel: p. 31, 85, 123

QQUIJADA I. Emma: p. 103, 117

RRAMIREZ Rafael: p. 1RAVNAS Rodmar: p. 77REITH Geoff: p. 105REYNAUD Jean-Yves: p. 107RIETHMUELLER Rolf: p. 45ROSSI Valentina: p. 109ROZET Marianne: p. 127RUBINO Jean-Loup: p. 99, 101, 107

SSAITO Yoshiki: p. 111SCASSO Roberto: p. 113SCHUSTER Mathieu: p. 99, 101SEIBEL Meg: p. 29SHANG Shuai: p. 39SOLIER Luc: p. 127SON Chang Soo: p. 115SONG Shengli: p. 129SORREL Philippe: p. 121SPALLUTO Luigi: p. 83STEEL Ronald: p. 23, 109SUAREZ-GONZALEZ Pablo: p. 103, 117

TTANAKA Akiko: p. 119TESSIER Bernadette: p. 49, 107, 121, 135THOMAS Sandrine: p. 127TIMUR Erol: p. 61TRENTESAUX Alain: p. 85, 91, 123TRIBOVILLARD Nicolas: p. 91TU Jinbiao: p. 39TURKMEN Banu: p. 61

VVALERIUS Jennifer: p. 125VAN ZOEST Michael: p. 125VEIGA Gonzalo: p. 55VENNIN Emmanuelle: p. 107VIEL Félix: p. 49VREL Anne: p. 127

WWANG Dong: p. 129WANG Ling: p. 129WANG Ping: p. 141WANG Ya Ping: p. 131WANG Yunwei: p. 133WEILL Pierre: p. 135WESTERBERG Lars-Ove: p. 93WINTER Christian: p. 57WU Jichun: p. 129WU Yijing: p. 39

YYIN Yong: p. 137YOO Dong-Geun: p. 17YU Qian: p. 133, 139

ZZEILER Manfred: p. 125ZHANG Jicai: p. 141ZHU Qingping: p. 129

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programme tuesday, july, 31