1

breakerThe Nansen IceWinter 1996, Number 8

A newsletter from the Nansen Arctic Drilling Program

Northern 2Highlights

Polarstern returnsto the Eurasionmargin 6

TRANSDRIFTIII 10

Laptev & Siberianseas survey 11

NAD contacts 12

Inside

ARCTIC OCEAN ’96:Pilot deep sea drilling in the central Arctic OceanYngve Kristoffersen, University of Bergen/University of Tromsø, Norway and Jan Backman, Stockholm Univeristy, Sweden

Figure 1. Sketch of icebreaker Oden and the position of the drill rig.

During Fridtjof Nansens’s famous drift withFram, O.B. Bøggild was entrusted with examiningthe first four sediment samples ever recoveredfrom the deep Arctic Ocean basin. He publishedhis results “in the hope that a tolerably clear ideathereby be obtained of the lithology of the bottomof the North Polar Sea.” One hundred years later,after more than 600 sediment cores (mostly 2 to 5m long) have been recovered and analyzed, we arestill totally missing the stratigraphic representa-tion of a 40 million year interval in the Cenozoic.This interval holds clues to the paleoceanographicresponse of the Arctic Ocean to Cenozoic globalcooling. In many ways, our scientific progresswith respect to the pre-Pleistocene history of thedeep Arctic Ocean has reached a plateau over thepast decade, except for the exciting data comingfrom the tireless effort of Art Grantz and the USGSgroup investigating the Chukchi Borderland.

The objective of the Nansen Arctic DrillingProgram (NAD) is to reach the stratigraphic andpaleoenvironmental treasuresbeyond the range of a gravitycorer. We have put a substantialeffort into defining targets in theNAD Science Plan and in earlierproposals to ODP by Peta Mudieand others. We have listenedrespectfully to engineers regard-ing the technical issues andlearned that, “Yes, it is possiblebut it will cost a lot of money.”

NAD has taken a phasedapproach to the problem byconcentrating first on thecontinental margins. Specifi-cally, NAD has taken interest ina potential deep borehole intothe Beaufort-Mackenzie sedi-mentary basin to be drilled incollaboration with the oilindustry, as well as a series ofholes drilled from fast ice in theLaptev Sea (see the 7/95 Ice-

breaker). A phased approach to exploring the deepocean is also needed, before we call on tools of thesize of JOIDES Resolution. We have observed thegreat practical issues that arise whenever thedrillship is near the ice edge. The inevitableconclusion is that the JOIDES planning structure isunlikely to make a firm commitment for deepArctic Ocean drilling because of all the hazardsinvolved. Therefore, the simplest way forward isto explore if we can advance and build experiencein a way that is less resource demanding than theengineers originally perceived.

ARCTIC ‘91, when Oden and Polarstern pen-etrated into the central Arctic Ocean, was abreakthrough. Excellent seismic data was obtainedusing the same method Art Grantz had in 1987from Polar Star over Northwind Ridge. Newdrilling sites were defined on the LomonosovRidge where Eocene (probably) and youngersediments are exposed by erosion at the ridge

continued on page 4

2

Northern HighLights

NAD begins breaking ice

The past year has been an important one forthe evolution of the Nansen Arctic DrillingProgram (NAD). In July 1995, a proposal writtenby Dr. G. Leonard Johnson (Chair, NAD Execu-tive Committee) and Dr. Garrett Brass (NADTechnology Committee), was presented to theJOIDES Executive Committee (EXCOM). JOIDES(Joint Oceanographic Institutions for Deep EarthSampling) is the advisory structure for theinternational Ocean Drilling Program (ODP). Thisproposal aimed to build cooperation with ODPwhich would provide NAD with an infrastruc-ture of management, science advice and coordi-nation, and a potential working system of reposi-tories and databases, through access to thoseaspects of the Ocean Drilling Program structure,at cost.

JOIDES EXCOM enthusiastically endorsed theexploration of closer ties between NAD and ODPin a consensus statement which includes thefollowing, “EXCOM recognizes that NADaddresses fundamental scientific problems inregions of the world, and requires facilitiesbeyond ODP capability.” Subsequently, the NADproposal was reviewed by the JOIDES PlanningCommittee (PCOM) in August 1995. PCOM, thehighest JOIDES scientific planning body, stronglyencouraged further discussion and exploration ofcommon interests and possible linkages betweenthe management and planning processes of NADand ODP/JOIDES. By motion, PCOM alsorecommended a framework to EXCOM forlinkage to other programs. EXCOM addressedthis subject and the PCOM motion at its January1996 meeting. By motion, EXCOM “stronglyendorses closer ties with international groupsinvolved in studying the Earth using drilling orcoring platforms or proposing to use such plat-forms, including the JOIDES Resolution. Initiationand strengthening of such ties must be without

prejudice to the scientific goals and legal mandatesof the JOIDES enterprise.” This statement echoedthe general PCOM endorsement.

There have been two NAD meetings since thelast issue of the Icebreaker. The first was a generalinterest meeting held during the May 1995 Ameri-can Geophysical Union meeting in Baltimore, USA.The second was an open NAD business meetingheld in October 1995 during the Fifth InternationalConference on Paleoceanography (ICP-V) inHalifax, Canada. At the first meeting it becameclear that a “NAD Implementation Plan” is neededand the second meeting affirmed the idea.

The purpose of a NAD Implementation Plan willbe to outline the strategy and steps necessary toachieve NAD’s scientific goals. Because of thedifficult and costly nature of scientific oceandrilling in the Arctic, the endeavor will requireclose multinational cooperation and funding. TheImplementation Plan will be the action plan tomobilize the NAD member and observer countriesto pursue the objectives outlined in the NADScience Plan. Creating an Implementation Plan aimsto establish international consensus and support.The plan is intended to be international in scopeand plans for individual member country activitiescan be embedded in it. It is also essential for theNAD Implementation Plan to consider the next stepin establishing a relationship with JOIDES.

A strawman NAD Implementation Plan iscurrently being developed by the chairs of theNAD committees. This plan will be discussed andfinalized at a workshop that is currently beingplanned for May 1996. If you wish to be on aspecial mailing list in order to review the draft planor to receive a workshop notice, contact the NADSecretariat at JOI (ajohnson@brook.edu; fax: 202-232-8203). Expressions of interest must be receivedby April 1, 1996.

3

Russia considersODP membership

A special workshop was held in Moscow onNovember 26, 1995 to discuss the future collabora-tion of the Russian scientific community with theOcean Drilling Program (ODP). The workshopwas organized by the Institute of the Lithosphere,Russian Academy of Sciences. Dr. Dave Falvey,Director of the Ocean Drilling Program, attendedand met with the Directors of Russia’s major earthscience institutions (including the Academy ofSciences, the Shirshov Institute, and the Instituteof Geology), the Russian Ministry of Geology, aswell as representatives of the Russian oil and gasindustry. Russian scientists have both a stronginterest in Arctic science and experience withArctic drilling. All participants were pleased to seethe developing connection between the NansenArctic Drilling Program and ODP. All involved inthe meetings and workshop are optimistic andexcited about Russia’s possible future participa-tion in ODP.

The submission deadline for the next issueof The Nansen Icebreaker is 1 July 1996. Send yourtext (and graphics) to: Andrea Johnson, Editor,The Nansen Icebreaker, Joint OceanographicInstitutions, Inc., 1755 Massachusetts Ave., NW,Suite 800, Washington, DC 20036-2102, USA.Tel: (202) 232-3900 ext. 213; Fax: (202) 232-8203;Internet: ajohnson@brook.edu. Text submittedby e-mail or on computer disk is appreciated.

Contributions to theIcebreaker are welcome!

Russia is proposing several drill sites in theRussian Arctic for collaborative internationaldrilling in the future. These sites are in the Barents,Kara and Laptev seas. Relatively easy access—aswell as oil and gas potential—makes the BarentsSea interesting. Scientifically, drilling in the BarentsSea would provide data on the late Cenozoicevolution of the western Russian Arctic. In contrast,drilling in the Kara Sea will explore Triassic riftsand grabens as well as a rich Cenozoic record withhigh terrigenous inputs. The Laptev Sea sites arethe same sites that were promoted at the NADLaptev Sea drilling workshop in late 1994. Thesesites would penetrate a rift system filled with thicklayers of Cenozoic sediments.

Russia proposesArctic drill sites

A full color map titled “Tectonic Elementsof the Arctic” and a detailed wall chart titled“Stratigraphic distribution of oil and gasdeposits in the former Soviet Union” areavailable from the Cambridge Arctic ShelfProgramme (CASP). The map, designed forwall display, shows the principal tectonicelements of the circum-Arctic region presentedon a polar stereographic projection. It includesWest Siberia, the Alaskan North Slope andTiman-Pechora and has been prepared jointlyby CASP (Cambridge, UK) and Aerogeolgiya(Moscow). This map is part of CASP’s RegionalArctic Project which is an ongoing geologicalsynthesis of the Late Paleozoic and Mesozoicsedimentary basins of the Arctic.

The wall chart includes data on the stratig-raphy, depositional environments and hydro-carbon occurrence in 80 areas of the major oiland gas provinces of the former Soviet Union(FSU). It includes all period, stage and areanames in both English and Russian (Cyrillicscript) plus a map of all FSU provinces produc-ing oil and gas. For an order form and priceinformation please contact: CASP, West Build-ing, Gravel Hill, Huntingdon Road, Cambridge,CB3 0DJ, UK Fax: +44 1 223 27 6604.

Arctic map andwall chart are available

4

because the vessel did not hold position wellenough relative to the water depth. Several trialswere scheduled in 1995 and the approach is beingtruly tested on the continental shelf in Antarcticaby drilling in 400 m water depth from the Finnishresearch vessel Aranda in January-February 1996.

Sweden is planning a scientific expedition tothe central Arctic Ocean in July-September 1996 incooperation with the Alfred Wegener Institute forPolar and Marine Research (ARCTIC OCEAN ‘96).The Swedish Polar Science Committee respondedvery positively to a proposal for a comprehensivegeological sampling program on the LomososovRidge using the diamond drilling concept. Selcore,the newly-developed hydrostatic corer will serveas a backup system. The effort will focus on ob-taining Paleogene and Neogene pelagic sedimentsfor paleoceanographic studies. During Leg 1,fourteen days of ship time will be devoted togeological sampling in addition to conventionalcoring on Leg 2. Scientific crew rotation is planned

Figure 2. Target area for drilling on the Alaska-facing side of the Lomonosov Ridge.

perimeter (see 4/93 Icebreaker). With the keeninterest of Captain A. Backman, icebreaker Odenperformed a test of its ability to keep position in2.5 m thick sea ice drifting at several hundredmeters per hour. After the vessel broke through apressure ridge using a 30 m run to pick up mo-mentum, it had no problems keeping within 50 mof the location as the 2 km wide flow passed overthe site (see the 3/92 Icebreaker).

After looking for a suitable drill rig for severalyears, one of us (Kristoffersen) contacted anIcelandic drilling company while attending aJOIDES Technology and Engineering Develop-ment Committee meeting in Reykjavik in the fallof 1993. He learned that drilling rigs suitable forour objectives were actually available in Norway.A $900 drilling platform was built and, in May1994, tested from the University of Bergen re-search vessel in a fjord with a 130 m water depth.Much was learned from an operational point ofview, but not a grain of sediment was recovered

from the Eurasia Basin usinglong-range Russian helicoptersafter about 40 days.

The ice-covered sea surfacehas no vertical motion whicheliminates the need for heavecompensation of the drillingplatform. During Leg 1, geologi-cal sampling is proposed for theLomonosov Ridge using dia-mond drilling with a lightwireline rig mounted on the sideof the icebreaker (Figure 1). Thestrategy is to drill a transect ofup to 50 m deep holes from theshallowest part of the ridge (840m water depth) to the maximumcapacity of the drill string (1400m). The purpose is to capturemuch of a >500 m thick Eoceneand younger section of pelagicsediments that were depositedon the ridge and exposed byerosion at the ridge perimeter(Figure 2). Drilling deeper than50 m will be pursued if feasible.At each site, the upper 10-15 mof sediment will be recoveredwith Selcore.

The drill rig is a conventionalland exploration wireline rigwhich can handle a 1400 m drillstring and produce a 43 mm

ARCTIC OCEAN ’96, continued from page 1

5

Figure 3. The first commercial version of Selcore.

diameter core. Weight of the rig is 5 tons plus the17.5 ton weight of the drill string out of which 9.6tons is supported by the winch wire. The weightof the whole rig rests on the deck and the drillstring runs into the water in a protected chuteattached to the hull of the vessel. First an outerstring (outer diameter 73 mm) will be lowered toserve as casing. The casing is secured by the deepsea winch wire attached to the bottom end andclamped to the pipe at regular intervals. Thissetup will prevent the drill string whipping in thewater during rotation and will serve as a safetymeasure against accidental loss of equipment. Adrill string of outer diameter 63 mm is thenlowered inside the casing. If the latter is acciden-tally lost, it is still contained within the casing andcan be retrieved by a standard fishing operation.The sediment core is retained by an inner 3 m longcore barrel and brought to the surface inside thedrill string by a wire line whenever the diamonddrill bit has advanced 3 m.

A critical point will be protecting the drillstring below and above the water line as the vesselis breaking ice to maintain position in a polaricepack of 2 to 3 m thickness while drifting. Theicebreaker Oden has a Thyssen-Waas bow designwhich has a reamer wider than the hull forward ofthe bridge (Figure 1). The idea is to let the drillstring go into the water just behind the reamerwhere the ice stress against the side of the ship isrelieved. The Swedish Icebreaker Administrationwill design and implement an ice protectionsystem. This system will be tested in ice in Gulf ofBothnia during the winter of 1995/96. Furtheropportunities to improve on the ice protection willbe available during station work on the week-longtransit from the ice edge to the Lomonosov Ridgeat the beginning of the expedition.

The Norwegian drilling contractorTERRABOR A/S provides two decades of dia-mond drilling experience (6 to 8 rigs) whichinclude marine sediment sampling by wirelinedrilling from anchored barges in water depths upto 115 m for geotechnical studies for most of themajor bridges in Norway. The company will beinvolved in all the planned tests and the drilling inAntarctica in early 1996.

The proposed drilling is a high risk endeavor,but we feel a capable backup system is available inthe Selcore hydrostatic corer (Figure 3). Originally,incentive for this development was sedimentcoring from ice station FRAM-I in 1979 where <1m core was recovered (and provided the data forthe first published sedimentation rates on the

Gakkel Ridge). Selcore operates as a pile driverafter the initial penetration by free fall. More than20 times the energy is available for sea bed pen-etration compared to a conventional gravity corerof the same weight. This feature is importantwhen the primary goal is to obtain the pre-Pleistocene material. Selcore has been developedby Selantic Industrier A/S, Ågotnes in coopera-tion with University of Bergen with partialsupport of Elf Aquitaine, Norway and is now incommercial use on the global market for sea bedsurveys.

The NAD feasibility study for drilling opera-tions in the Arctic Ocean concluded that the bestapproach would be to use an icebreaker to clearthe way and to drill from another vessel or abarge. We have considered this, but another vesselmeans large added costs. A barge deployed from asingle icebreaker is too cumbersome and probablyis more a safety risk than an advantage.

We consider the proposed pilot drilling onLomonosov Ridge a contribution to the NansenArctic Drilling initiative and hope that a successfuloperation during ARCTIC OCEAN ‘96 will openfor a cost-effective approach to new advances inour understanding of the role of the Arctic Oceanin global climate evolution. If aluminum pipe isused, we will be able to access the crest of theAlpha Ridge with this rig size in the future.

6

The polar research vessel Polarstern made itssecond cruise (ARK-XI/1) to the Eurasian conti-nental margin and adjacent deep-sea from July 7to September 20, 1995. Scientists on board studiedoceanographic circulation patterns, the marineecosystem, sea-ice characteristics, and the deposi-tional environment and its change through the lateQuaternary (Rachor et al., in press). The main goalof the marine geological program was to performhigh-resolution studies of changes in paleoclimate,paleocirculation, paleoproductivity, and formersea-ice distribution. Of major interest was thesignificance of the Arctic Ocean for the globalclimate system, the correlation of paleoen-vironmental data from different depositionalenvironments, and the correlation of marine andterrestrial climatic records. Accordingly, detailedsedimentological, geochemical, mineralogical, andmicropaleontological investigations will beperformed.

Research will focus on:• high-resolution stratigraphy (isotopes, AMS-

14C-datings, amino-acids, and magneticsusceptibility);

• river run-off and corresponding surface-water

contributed by R. Stein, F. Niessen, M. Behrends, M. Bourtman, K. Fahl, M. Mitjajev,E. Musatov, N. Norgaard-Petersen, V. Shevchenko, and R. Spielhagen

Polarstern returns to the Eurasian margin:Report of the geology program

salinity changes (stable isotopes);• terrigenous sediment supply (grain size; clay-,

light-, and heavy minerals; organics;geochemical tracers);

• organic carbon fluxes (total organic carbon, C/N ratios, hydrogen and oxygen indices, carbonstable isotopes, maceral composition,biomarkers);

• reconstruction of paleoproductivity by traceranalyses (biomarkers, barium, biogenic opal);

• reactions of biota to environmental changes;• physical properties (magnetic susceptibility,

wet bulk density, porosity, shear strength);• specific depositional environments with

PARASOUND echo-sounding surveys.The research program will also investigate

aerosols, water column particles (using sedimenttraps and in situ pumps), surface sediments, andlong sediment cores. During the Polarstern expedi-tion ARK-XI/1, geologic sampling took place inthe western East Siberian, Laptev, and easternKara seas as well as the adjacent continental slopeand deep-sea (Figure 1). When possible, coringpositions were carefully selected usingPARASOUND to avoid areas of sedimentredeposition and erosion.

Lithostratigraphy and sediment characteristicsAll surface sediments obtained during ARC-

TIC’95 indicated well-oxygenated surface layers.On the shelf and on the upper slope, sedimentswere described as ranging from sandy silty clay tosilty sand, while on the lower slope and in thedeep sea, silty clays were predominant. Oneexception was the Lomonosov Ridge’s easternflank (Transect F) and the adjacent Makarov Basin(Transect A), where surface sediments containedsignificant amounts of sand — even in waterdepths greater than 1000 m. Currents across theLomonosov Ridge may be winnowing the finematerial.

In general, ice-rafted gravel was rare. How-ever, gravel up to 5 cm in diameter was commonin the cores taken north and northeast ofSevernaya Zemlya (200 to 1000 m water depth)reflecting major iceberg rafting.

One exceptional discovery was five flatmanganese nodules (4 to 7 cm diameter, 1 to 2 cmthick) on the surface of box core PS2726-5 from theshallow Eastern Laptev Sea (48 m water depth).Figure1. Polarstern cruise ARK-XI/1 (1995), geological stations and transects.

7

continued on page 8

Figure 2. Transect across the Lomonosov Ridge (Transect F in Figure 1, 81°N),geological stations and recovery. Polarstern cruise ARK-XI/1, 1995.

These nodules were also ob-served in several Agassiz trawlsfrom this area suggesting asignificant regional distribution.

The long sediment corestaken from the Eurasian conti-nental margin and the deep seaare dominated by terrigenoussilty clays. Sandy lithologies aswell as biogenic components arerare. The sedimentary sequencesshow distinct variations insediment color and the degree ofbioturbation, indicating majorchanges in the depositionalenvironment through time.

In general, the shelf coresfrom the western East SiberianSea and the Laptev Sea consist ofgray partly-bioturbated siltyclays. High Fe-sulphide amountsin many of the cores may be dueto the decay of marine organics by sulphate-reducing bacteria activity. Occasional well-preserved bivalves and shell debris will allowAMS-14C dating of the sedimentary sequences.

The continental slope and deep-sea cores, incontrast, are mainly composed of brown siltyclays. Most fine-grained material was probablytransported in suspension by currents and/or seaice. Athough transport by turbidity currentsbecomes very important on the lower slope.

Sedimentary sequences recovered from theAmundsen Basin, across the Lomonosov Ridge,and into the Makarov Basin are shown in Figures2 and 3. On this transect (F), ten stations weresampled using a giant box corer, a multicorer, anda gravity/kastenlot corer. The long cores havelengths between 4.9 and 9.1 m. A correlationacross the ridge is possible between the coresusing the degree of bioturbation, specific silty-sandy layers, and a prominent thick dark-grayinterval. This correlation is also supported bymagnetic susceptibility records (Figure 4).Changes in sediment composition suggest majorvariations in source-rock areas, transport pro-cesses, and/or biological productivity, probablyrelated to climatic (glacial/interglacial) variations.

The shipboard data is still being interpretedand is preliminary. The 14C ages for absolute age

control—as well as more detailed sedimentologi-cal, mineralogical, and geochemical studies—mustbe completed before sedimentary processes andtheir correlation to climate change can be preciselyreconstructed.

Sediment echosounding and physical propertiesDuring ARK-XI/1 the ice conditions allowed

nearly-continuous profiling and quality resultsusing the hull-mounted sediment echosoundingsystem PARASOUND (4kHz). Generally, thereflection pattern along the continental slopeshows a strong gradient of increasing sedimentthicknesses towards the continental shelf indicat-ing a predominance of terrigenous sedimentinput. However, on a more regional scale, differ-ent reflection patterns suggest major temporal andspatial changes of the depositional character.Based on interpretation of the PARASOUNDprofiles, five major areas can be distinguished.Discussion of each area follows:

(1) Laptev Sea ShelfOn the Laptev Sea shelf, PARASOUND can

penetrate 20 m subbottom showing well-stratifiedsediments of probable Pleistocene age, whichcommonly dip gently eastward. In places, strong

8

Polarstern, continued from page 7

tion down to 50 m sediment depth can be ob-served. The beginning of the lower fan (about 2300m) is characterized by diffraction hyperbolae. Thiscan be explained by small-scale morphologicalfeatures, such as numerous small channels, whichform the transition to the morphologically flatturbidite deposits of the Amundsen Basin. Duringthe ARK-IX/4 cruise in 1993, similar profiles wereinterpreted as river channels which were erodedduring glacial times when sea level was lowerand river mouths were near the present-day shelfedge. This entire pattern indicates a continuingsediment supply from the Eurasian continent intothe Arctic deep sea during the last glacial (stage 2).

(3) Western Laptev Sea Continental SlopeThe continental slope west of 120°10’E (be-

tween 2000 m and 3250 m water depth) is charac-terized by a large number of debris flow deposits.Typically, they appear in PARASOUND profilesas lenticular-shaped bodies (each about 30 mthick) which are acoustically transparent. They aremostly draped by a few meters of stratifiedsediments. The debris flows indicate that, at thetime of their deposition, there was a strongdownslope movement of sediments over a largearea of the western continental slope of the LaptevSea and off Severnaya Zemlya. Further analysisand dating of sediment cores is necessary todetermine whether their formation might havebeen controlled by a larger glaciation along theTaymyr-Severnaya Zemlya shelf.

(4) Gakkel RidgeThe deep-sea area of Transect D is dominated

by the geology of the Gakkel Ridge. There are twocrests seen along profile G (at 80°50.5’N, 122°05’Eand at 80°36.8’W, 121°01’E). West of 122°E there isevidence for several faulted blocks, more or lessvertically displaced by up to 200 m. The blocks areprobably related to oceanic crust sheared by sea-floor spreading. The blocks are draped by well-stratified sediments which allow sound penetra-tion to about 20 m sediment depth. West of120°45’E, PARASOUND profiles indicate thetransition into the Nansen Basin. Several smallerblocks of bedrock (ca. 1 km across and elevated upto 100 m above the sea floor) alternate laterallywith sediment fills of more than 30 m in thickness.It is assumed that the bedrock represents the

reflectors cut these well-stratified units roughlyparallel to the sea floor (10 to 20 m sedimentdepth), indicating their post-depositional origin.One possible explanation for the significantcontrast in acoustic impedance at these horizons isthe onset of sub-surface permafrost. A secondpossibility is a higher concentration of sedimen-tary gas at this depth.

(2)Eastern Laptev Sea Continental Slope In the central to eastern Laptev Sea, the

continental slope along Transect C down to 3200m water depth can be characterized as a deep-seafan facies. On the upper fan (down to about 1200m) typical channel and levee deposits appear.Several channels (up to 100 m deep) are observedwhich cause high acoustic backscatter—probablybecause of the coarser channel fill. In contrast,levee deposits are well-stratified. Sound penetra-

Figure 3. Lithological profile Amundsen Basin - Lomonosov Ridge - Makarov Basin(Transect F in Figure 1).

9

logging. In the susceptibility records the occurrenceof dark gray and very dark gray sediments ischaracterized by strong fluctuations and highamplitudes of up to 100 x 10-5 SI. These units arealso indicated by increased wet bulk densities (upto 1.9 g/cm3) and significantly higher P-wavevelocities (ca. 1600 ms-1). In general, the lateral corecorrelation across the Lomonosov Ridge usingmagnetic susceptibility is consistent with those ofwet bulk density and P-wave velocity. There is,however, some uncertainty in the correlationtoward the westerly end of the profile in theAmundsen Basin (Figures 3 and 4, cores PS2753-2and PS2754-8).

Reference:Rachor, E. (ed.) The Expedition ARCTIC '95, Leg ARK-XI/1 ofRV Polarstern 1995. Reports on Polar Research, Alfred WegenerInstitute, Bremerhaven (in press).

Figure 4. Correlation of core-logging results Amundsen Basin - Lomonosov Ridge -Makarov Basin (Transect F in Figure 1).

older, more distal parts of the fractured crust ofthe Gakkel Ridge. The blocks are increasinglyburied by sediments towards the Nansen Basin.This is indicated by reflectors which show theincrease of sediment thickness to the west. Theonlap geometry of the fill is typical for turbiditedeposits.

(5) Lomonosov RidgeAlong the transects across the Lomonosov

Ridge and the continental slope of the westernMakarov Basin (Transects A and E), thePARASOUND profiles are characterized by well-stratified sediments which drape subsurfacemorphologies. This implies a predominance ofmore pelagic conditions and thus relatively lowsedimentation rates. Penetration is generally up toabout 50 m. For most of the area, an upper seismicunit (A) of stronger backscatter can be distin-guished from a lower unit (B) which shows ahigher degree of acoustic transparency (Figure 5).This subdivision is more pronounced near thecrest of the Lomonosov Ridge and in the MakarovBasin and is less distinct towards the AmundsenBasin. The thickness of unit A varies between 4and over 30 m. The thinnest units are observed onand near the crest of the ridge. Also, there is asignificantly higher thickness of unit A toward theAmundsen basin compared to the Makarov side ofthe slope, which implies relatively low sedimenta-tion rates on the eastern (Makarov) part of thetransects. This is consistent with the correlation ofboth lithology (Figure 3) and magnetic susceptibil-ity (Figure 4) as determined by 1 cm-interval core

Figure 5. PARASOUND profile across the crest of the Lomonosov Ridge and seismic units A and B.

10

TRANSDRIFT III expedition studies Laptev Seacontributed by Heidemarie Kassens, GEOMAR

well as workshops and the exchange of scientists.The GEOMAR Research Center for Marine Geo-sciences in Kiel, Germany and the State ResearchCenter for Arctic and Antarctic Research in St.Petersburg, Russia, are jointly responsible fororganizing and coordinating the multidisciplinaryproject, which is funded by the Russian and Ger-man Ministries of Science and Technology.

The successes of the pilot phase (AMEI’91 toKotelnyy, ESARE’92 to the Lena Delta and the NewSiberian Islands, and TRANSDRIFT I to the LaptevSea in 1993) as well as the LENA’94 expedition tothe River Lena and the TRANSDRIFT II expeditionto the Laptev Sea on board RV Professor Multanovskyin 1994 were very encouraging. This prompted thenext expedition, TRANSDRIFT III, to be planned forthe autumn to study freeze-up processes in theLaptev Sea; a first for this time of year. Conse-quently, the expedition logistics were extremelydifficult. The expedition out of Murmansk on theRussian icebreaker Kapitan Dranitsyn had 50 scien-tists from Russia and Germany and took place from1 to 30 October 1995.

The TRANSDRIFT III expedition mainlytargeted the eastern Laptev Sea, e.g., the Lena Deltaand the region of the Laptev Sea polynya. Thehighest priority program objectives were to study:• the extent and composition of sea ice,• incorporation processes of various particulates

into new ice,• alteration of oceanographic and hydrochemical

processes during ice formation,• impact of ice cover on the biological productivity.

The TRANSDRIFT III cruise was joined by thesecond land expedition to one of the main sourceareas of the eastern Laptev Sea, the Lena and Yanarivers. The work here specifically concentrates on:• identification of riverine geochemical and miner-

alogical tracers,• qualification and quantification of sediment

transport.

Although the impact of the polar regions onglobal climate is recognized, there is much to learnabout the impact of climate on the Arctic Ocean.For instance, limited knowledge of how climatechanges influence sea-ice formation makes itdifficult to predict possible future global climatechanges. This is true for the Siberian shelf seaswhere large amounts of Arctic sea ice are formedand which, for logistical and political reasons,have been inaccessible to the international scien-tific community. The Laptev Sea is of particularinterest because it’s a source area for both the Transpolar Drift and sediment-loaded sea ice. In the Laptev, it might be possible to demonstrate the extent to which global ocean circulation and climate development are influenced by extremely large influxes of freshwater from the Siberian river systems. Current oceanographic models have not yet consid- ered such a direct terrestrial impact on the global climate.

The Russian scientific community has long worked on the Siberian shelf seas because of their oil, gas and mineral resources aswell as the economic advantages of the NorthernSea Route. Unfortunately, only a few of manyRussian scientific reports have been translated toother languages. U.S. data from the 1960s andsome recent studies also clearly point to the centralimportance of the Siberian shelf seas for the Arctic.However, little was known about the complexgeosystem of the Laptev Sea.

In 1994, a major multidisciplinary researchprogram ‘Laptev Sea System’ was designed byRussia and Germany to understand the Arcticenvironment and its significance for the globalclimate. Ongoing bilateral research activitiesinclude land and marine expeditions to the LaptevSea area during different seasons of the year as

11

contributed by G. Leonard Johnson, GERG, Texas A&M University

nivorous and bottom feeders) and other localfauna were obtained to determine their contami-nant levels. Of NAD interest were two cores takenat the proposed NAD sites for Laptev Sea drilling(Figure 1). Both cores are being analyzed forphysical properties and for hydrocarbon traces.

Southerly winds created the area’s lightest iceyear since 1945 and allowed good access. Thisopportunity was optimized with ice forecasting byon-board AARI scientists using U.S. and Russianreal-time satellite data. Of special interest was animmense surface freshwater lens (salinity: 10-15ppt; surface temp: 10°C; thickness: 5-10 m) ex-tending north from the coast to the latitude ofNovaya Sibir Island.

The chartered Russian research vessel, Y. Smir-nitsky, was excellent and the captain and crewwere very cooperative. Permits were coordinatedby the GERG Moscow Office, and the charter washandled by VICAAR, a logistic support companylocated in St. Petersburg, Russia.

During the summer of 1995, the RV Y. Smir-nitsky made a reconnaissance survey in the Laptevand East Siberian seas. With support from the U.S.Office of Naval Research’s Arctic Nuclear WasteAssessment Program, the Geochemical andEnvironmental Research Group (GERG) of TexasA&M University conducted the survey jointly withseveral Russian institutes. The primary Russianinstitutes involved were: the Arctic and AntarcticResearch Institute (AARI), the State Enterprise All-Russia Research Institute for Geology and MineralResources of the World Ocean (VNII Okeangeo-logia), and the Research Institute for Nature Con-servation of the Arctic and the North (RINCAN),and the Tiksi Nature Reserve.

The survey program focused on the interactionof Arctic Ocean water with the discharge frommajor Siberian rivers. Sampling (Figure 1) in-cluded CTD, nutrients, oxygen, as well as watersamples for contaminants and radionuclides andseafloor samples for physical properties, radionu-clides, contaminants, organic carbon, paleostrati-graphy and benthic fauna. Samples of fish (car-

Figure 1. 1995 Laptev and East Siberian Seas sampling stations. Stations 59 and 60 are proposed NADsites (DS-3: 74°48'N, 134°15'E and DS-7: 73°54'N, 135°E)

Joint U.S. and Russian survey ofLaptev and East Siberian seas conducted

12

breakerThe Nansen Ice

The Nansen Ice breakerNewsletter Editor: Andrea JohnsonNewsletter Design: Johanna Adams

The Nansen Icebreaker is issued twice a year by Joint Oceano-graphic Institutions, Inc. (JOI). JOI serves as the Nansen ArcticDrilling Program (NAD) Secretariat. NAD is supported by contri-butions from its member nations: Canada, France, Germany, Japan,Norway, Sweden, the United Kingdom, and the USA. Denmark,Iceland, Russia, and The Netherlands participate as observers.

Any opinions, findings, conclusions, or recommendations ex-pressed in this publication do not necessarily reflect the views ofJOI, NSF, or the NAD member institutions. Please contact the JOIOffice for more information or to subscribe. The Nansen Icebreakeris available free of charge and is printed on recycled paper.

The sidebar photo is used courtesy of the Scott Polar ResearchInstitute. Close inspection of the photo reveals the Polar Bjørn duringthe MIZEX ‘84 expedition.

Dr. Richard HaworthDirector GeneralGeological Survey of Canada601 Booth StreetOttawa, Ontario K1A 0E8CANADA

Dr. Jean-Claude SibuetDept. des Geosciences MarinesIFREMER BP 7029280 PlouzaneFRANCE

Prof. Dr. Dieter FüttererAlfred Wegener Inst. für Polar- und MeeresforschungColumbusstraße, Postfach 120161D27515 BremerhavenGERMANY

Dr. Gunnar OlafssonIcelandic Museum of Natural HistoryP.O. Box 5320125 ReykjavikICELAND

Dr. Nobuo OnoArctic Environ. Research CenterNational Institute for Polar Research9-10, 1-Chome, Itabashi-kuTokyo 173JAPAN

Prof. Dr. Tore O. VorrenDepartment of Geology, IBGUniversity of TromsøP.O. Box 3085N-9001 TromsøNORWAY

Prof. Dr. Kurt BoströmDepartment of GeologyUniversity of StockholmS-10691 StockholmSWEDEN

Dr. Roger PadghamEarth Sciences DirectorateNatural Environ. Research CouncilPolaris House, North Star AvenueSwindon SN2 1EUUNITED KINGDOM

Dr. G. Leonard Johnson4601 N. Fairfax DriveSuite 1130Arlington, VA 22203USA

Dr. Vladimir PavlenkoArctic Research CentreRussian Academy of Sciences4, Shvernick117036 MoscowRUSSIA

Dr. Naja MikkelsenGeological Survey of DenmarkThoravej 312400 CopenhagenDENMARK

Dr. Jan H. Stel, DirectorThe Netherlands Geo- sciences FoundationLaan van Nieuw Oost Indië 131NL-2509 AC The HagueTHE NETHERLANDS

NAD points of contactThe NAD Executive Committee

Nansen Arctic Drilling Program SecretariatJoint Oceanographic Institutions, Inc.1755 Massachusetts Ave., NW, Suite 800Washington, DC 20036-2102 USA

Non-Profit Org.US Postage

PAIDWashington, DCPermit No. 2268