2
Participant - surname
Participant - first name
Institute Title
Al-Halbouni Djamil GFZ Distinct Element modeling of geophysical signatures during sinkhole collapse
Aranda Viana Germán UP Imaging and photogrammetry models of western scarp of the Candelaria range by Unmanned Aerial Vehicles
Arnous Ahmad UP Landscape evolution in response to reactivated faults in the broken foreland of southern Central Andes, NW Argentina
Borghini Alessia UP Variscan nanogranitoids in Bohemian Massif garnet clinopyroxenites: evidence for metasomatism and partial melting?
Brenner Johannes UFZ Towards reliable evapotranspiration in the semi-arid Júcar region
Coch Caroline AWI
Hydrological and sedimentary response of small watersheds in a Low Arctic setting – A case study on Herschel Island, Yukon Territory, Canada
Codeço Marta GFZ Chemical and 𝜹11B variations in tourmaline from the Panasqueira W-Sn-Cu deposit, Portugal
Escalante Leonardo UP
Allufial-fan terraces as strain markers for Quaternary contractile deformation in the interior of the southern Central Andes: Intermontane alluvial basin fills in the Calchaqui Valley of the Eastern Cordillera (Cachi-Payogasta area), NW Argentina (25°03'S, 66°07'W)
Figueroa Villegas
Sara UP
Holocene Tectonic Deformation Processes in the Transition between Sierras Pampeanas and Eastern Cordillera, Cafayate Valley (26°00’ – 25°50’LAT., 66°00’-65°50’LONG.),Salta
Friese André GFZ A simple and inexpensive technique for assessing contamination during drilling operations
Gholamrezaie Ershad UP 3D structure and conductive thermal field of the sea of Marmara
Ibarra Federico UP Lithosphere-scale 3D gravity and thermal modelling of the Central Andes
3
Participant - surname
Participant - first name
Institute Title
Korges Maximilian GFZ Quantification of ore-forming processes in magmatic hydrothermal Sn-W systems: a fluid inclusion study of the Zinnwald deposit
Liu Sibiao GFZ Influence of the orogenic lithospheric strength on the deformation of the foreland upper crust
Lorenz Melanie UP
REE variations in the pre-Andean crustal basement: Enrichment in a shear zone of Ordovician granitoids and mineralization in a fenitized Devonian monzogranite, Eastern Sierras Pampeanas
Maerz Sven UP
Pore Type Characterization and Detection of Effectice Pore Network with Digital Imge Analysis: A case study from Miocene Lacustrine Carbonates (Southern Germany)
Meijer Niels UP Astronomical forcing of Eocene monsoons
Müller Sebastian UP Extending Theis’ solution to incorporate heterogeneity into pumping test analysis
Nooshiri Nima GFZ Revision of earthquake hypocentre locations in global bulletin data sets using source-specific station terms
Ötztürk Ugur UP Identifying Typhoon Tracks based on Event Synchronization derived Spatially Embedded Climate Networks
Pascual Montanés
Joan GFZ High-resolution reconstruction of past climate and environment from lacustrine deposits in NW Argentina
Pommerencke Julia UP Rock Glacier Response in Changing Climate
Purinton Ben UP Digital topography for geomorphology and beyond: frontiers in meters to sub-meter resolution remote sensing
Ramage Justine AWI Terrain Controls on the Occurrence of Coastal Retrogressive Thaw Slumps along the Yukon Coast, Canada
4
Participant - surname
Participant - first name
Institute Title
Ramezani Ziarani
Maryam UP Determining hydroclimatic extreme events over the south-central Andes
Ruiz Ricardo GFZ Organofacies of the Yacoraite Formation, Salta Basin; Argentina
Schmidt Wera UP Testing long-term controls of sedimentary basin architecture, Tres Cruces Subbasin, Jujuy, Argentina
Siegmund Nicole ZALF Interaction between small scale landscape structure and erosive wind events in La Pampa, Argentina
Stolle Amelie UP Mountain rivers may need centuries to adjust to earthquake-triggered sediment pulses, Pokhara, Nepal
van der Veen Iris UP Defining moisture sources and organic matter transport processes in the NW Himalaya
Wetzel Maria GFZ Numerical homogenization approach for coupling of chemical and mechanical processes in the geological subsurface
5
Distinct Element modeling of geophysical signatures during
sinkhole collapse
Djamil Al-Halbouni, Eoghan P. Holohan, Abbas Taheri, Torsten Dahm
A sinkhole forms due to the collapse of rocks or soil near the Earth’s surface into an
underground cavity. Such large secondary pore spaces are derived by dissolution and
subrosion in the underground. By changing the stress field in the surrounding material, the
growth of cavities can lead to a positive feedback, in which expansion and mechanical
instability in the surrounding material increases or generates new secondary pore space. The
development of models for the mechanical interaction of a growing cavity and fracturing of its
surrounding material has been limited, however.
Here we report on the advances of a general, simplified approach to simulating cavity growth
and sinkhole formation by using 2D Distinct Element Modeling (DEM) PFC5.0 software and
thereby constraining pre-, syn- and post-collapse geophysical and geodetic signatures. This
physically realistic approach allows for spontaneous cavity development and dislocation of
rock mass to be simulated by bonded particle formulation of DEM.
The proposed model development and a possible archive of modeled scenarios may, in
combination with a geodetic and seismological sinkhole monitoring, contribute to an early-
warning tool for end-users and decision makers in areas affected by natural (e.g. Dead Sea)
or man-made sinkhole collapses (mines).
6
Imaging and photogrammetry models of western scarp of the
Candelaria range by Unmanned Aerial Vehicles
Rodolfo G. Aranda 1.2, Carlos Bianchi 1, Alejandro Aramayo 1, Luis Alvarado 1, Ahmad
Arnous 2,3, Fernando D. Hongn 1, Manfred R. Strecker 2
1Instituto de Bio y Geociencias del NOA (CONICET-UNSa), 4405, Salta, Argentina. E-
mail: [email protected].
2Instituto de Ciencias de la Tierra y del Medio Ambiente, Universidad de Potsdam, 14476
Potsdam, Alemania, [email protected], 14476.
3Instituto Miguel Lillo, Universidad Nacional de Tucumán, 4000, Tucumán,
[email protected], 4000.
We present new high-resolution topographic data obtained with an Unmanned Aerial Vehicle
(UAV) and photogrammetric techniques to generate a digital cartographic base for future
earthquake-geology and tectonic geomorphology studies in the western edge of the
Candelaria range, Salta Province (Argentina). The surveyed region covered a rectangular area
of 1.82 km², which was chosen perpendicular to the inferred scarp and identified by terrestrial
control points using geodetic GPS. The set of images obtained were rectified in an
orthomosaic, then created a digital surface model (DSM) with a spatial resolution of 5.75 cm /
pixel. The digital elevation model (DEM) was derived from the original digital surface model,
filtering topographical anomalies related to the vegetation cover, following a combination of a
multi-stage automatic algorithm and manual filtering of noise. These results constitute one of
the first attempts to obtain high quality imagery in the area. Overall, the digital dataset produced
is intended to support neotectonics investigation in this region, and provide tools introduce new
workflows for the creation of Digital Elevation Models.
7
Quaternary Activity of the Canderlaria Fault, NW Argentina (26° LAT,
65° LON): New Insights from Geomorphic Mapping and Electrical-
Resistivity Prospecting
Ahmad Arnous 1.2, Angela Landgraf 2, Julien Guillemoteau 2, Antonio Gutierrez 1,
Rodolfo G. Aranda 1.2, Manfred R. Strecker 2
1Instituto Miguel Lillo, Universidad Nacional de Tucumán, 4000 Tucumán
2Institute of Earth and Environmental Science, University of Potsdam, 14476 Potsdam,
Germany
Quaternary deposits in the broken foreland of NW Argentina record the spatially and temporally
disparate character of tectonic activity. The Candelaria basement-cored range has
experienced seismicity on its western flanks, where the Candelaria Fault also offsets
Quaternary deposits and forms a pronounced topographic break. Vertical offsets of up to 15m
along the fault scarp affect Quaternary alluvial-fan deposits and point to potential earthquake
hazards along this fault.
our geomorphic mapping of the fault using satellite images and digital elevation models of 5m
reveals different generations of alluvial fans.
In an attempt to reveal the geometry and kinematics of the responsible faults, we acquired a
set of 2D electrical resistivity tomography (ERT) data perpendicular to the strike of the fault.
During an exploratory survey.
The resulting cross-sections of electrical resistivity show a significant contrast below the
inferred fault-scarp position at the surface.
The consistency between our geomorphic mapping and the electrical profiling led us to
interpret the prominent scarp as a reverse fault, where the western block is the hanging-wall
block that was thrust onto fan deposits along a westward-dipping fault.
8
Variscan nanogranitoids in Bohemian Massif garnet
clinopyroxenites: evidence for metasomatism and partial melting?
Alessia Borghini (1), Silvio Ferrero (1,2), Bernd Wunder (3), Laurent O. (4) , Patrick J O’Brien (1),
and Martin A. Ziemann (1)
(1) Universität Potsdam, 14476 Potsdam, Germany,
(2) Museum für Naturkunde (MfN), Leibniz-Institut für Evolutions-und Biodiversitätsforschung,
10115 Berlin, Germany
(3) Helmholtz-Zentrum Potsdam, GFZ, D-14473 Potsdam, Germany
(4) ETH Zürich, 9082 Zürich, Switzerland
Primary nanogranitoids have been identified in garnet from the garnet clinopyroxenites of the
Granulitgebirge, Bohemian Massif. Their distribution as clusters in garnet confirms they formed
during garnet growth. The inclusions can be polycrystalline or glassy and from 5-20 μm in
diameter. The phases were identified by Micro Raman Spectroscopy and the assemblage is
kumdykolite/albite, phlogopite, osumilite, kokchetavite and quartz and were identified. This
association of minerals and the presence of preserved glassy inclusions are consistent with
the origin of these inclusions as former droplets of melt.
Nanogranitoids have been re-homogenized at 1000°C, 22 kbar to a hydrous glass of quartz-
monzonitic composition in a piston cylinder apparatus. The chosen conditions correspond to
the formation of the garnet and thus of melt entrapment. The preliminary interpretation of
normalized trace element data show that the trapped melt is enriched in Cs, Rb and Pb. Such
patterns suggest the involvement of a white mica in the melt-producing reaction.
The studied garnet clinopyroxenites are enclosed in bodies of serpentinized garnet peridotites
hosted in turn in HP felsic granulites. They show a granoblastic texture dominated by garnet
and clinopyroxene with interstitial plagioclase, biotite, two generations of amphiboles and rutile
and ilmenite as accessories. The bulk rock composition is basic to ultrabasic.
These inclusions may be the result of two different possible processes: 1) localized melting of
metasomatized mafic rocks with simultaneous production of garnet, 2) or an interaction
between melted felsic granulites and metasomatized peridotites with consequent formation of
these garnet clinopyroxenites.
9
Towards reliable ET estimates in the semi-arid Júcar region in Spain
Brenner J.1, Zink M.1, Schrön M. 1, Thober S.1, Rakovec O.1, Samaniego L.1
1 Helmholtz Centre for Environmental Research–UFZ, Leipzig, Germany.
Current research indicated that the there is potential for improving evapotranspiration (ET)
estimates in state-of-the-art hydrologic models such as the mesoscale Hydrological Model
(www.ufz.de/mhm). Most models exhibit deficiencies to estimate the ET flux in semi-arid
regions. Possible reasons for poor performance may be related to the low resolution of the
forcings, the estimation of the PET, the joint estimation of the transpiration and evaporation,
poor process parameterizations, among others.
In this study, we aim at sequential hypothesis-based experiments to uncover the main reasons
of these deficiencies at the Júcar basin in Spain. We plan the following experiments: 1) Use
the high resolution meteorological forcing (P and T) to estimate its effects on ET and
streamflow. 2) Use local ET measurements eddy covariance stations to estimate evaporation
related parameters. 3) Test the influence of the PET formulations (Hargreaves-Samani,
Priestley-Taylor, Penman-Montheith).
We set-up mHM for two eddy-covariance sites at the local scale. In the second experiment, for
example, a parameter set is to be found as a compromised solution between ET measured at
local stations and the streamflow observations at eight sub-basins of the Júcar river.
Preliminary results indicate that higher model performance regarding streamflow can be
achieved using local high-resolution meteorology. ET performance is, however, still deficient.
On the contrary, using ET site calibrations alone increase performance in ET but yields in poor
performance in streamflow. Results suggest the need of multi-variable, simultaneous
calibration schemes to reliable estimate ET and streamflow in the Júcar basin.
10
Hydrological and sedimentary response of small watersheds in a
Low Arctic setting – A case study on Herschel Island, Yukon
Territory, Canada
Caroline Coch, Hugues Lantuit, Scott Lamoureux
Coastal ecosystems in the Arctic are being affected by climate change leading to permafrost
thaw, to a shifting streamflow regime and to changing fluxes of freshwater and sediment to the
Arctic Ocean. The hydrological and sedimentary response of large rivers to climate change
have been focus of numerous investigations as they cover 53% of the area draining into the
Arctic Ocean. Small catchments are yet widespread and could contribute large amounts of
sediment to the nearshore zone. Streamflow and sediment transport is being monitored
continuously only at a few sites, which constraints the understanding regarding water quality
and nutrient availability. This project is addressing this knowledge gap by investigating
streamflow regime and sediment dynamics of two adjacent catchments on Herschel Island in
the western Canadian Arctic. By comparing both watersheds, sediment sources and controls
of its mobilization are going to be investigated. This study will contribute to a baseline for pan-
Arctic assessments of sediment flux to the Arctic Ocean.
11
Chemical and 𝜹11B variations in tourmaline from the Panasqueira W-
Sn-Cu deposit, Portugal
Marta S. Codeço1, Philipp Weis1, Robert B. Trumbull1, Filipe Pinto2, Pilar Lecumberri-Sanchez3
1GFZ German Research Centre for Geosciences, Potsdam, Germany
2Beralt Tin & Wolfram (Portugal), Barroca Grande, Portugal
3Dep. of Geosciences, University of Arizona, Tucson, USA
The Panasqueira W-Sn-Cu vein-type deposit in Portugal is Europe’s largest tungsten deposit.
The subhorizontal W-Sn-Cu-bearing quartz veins are hosted by metasedimentary units of the
Beira Schists and spatially related to a greisenized cupola of an S-type granite [1]. Tourmaline
is absent in the greisen but abundant in wallrock alteration zones which predate the main ore
stage. Tourmaline is also found in late-stage vugs.
We report results from high-resolution in-situ measurements (microprobe and SIMS) showing
the variations in chemical and boron isotopic compositions of tourmalines from the
Panasqueira deposit. All tourmalines have Li-free ferromagnesian compositions and display
optical and chemical zoning. The results show an increase in Fe, F and Na and decrease in
Mg, Al and Ca from core to rim. The total range in tourmaline B-isotope compositions is from
11B -13.3 to -3.7‰, including tourmaline from the wallrocks and vugs. These values are
compatible with either local metasedimentary or granitic sources. However, given the volume
of tourmaline and association with F, W, Sn, Ta, Nb, we consider a boron source from the
adjacent granite more likely.
The results suggest a dynamic hydrothermal system with multiple injections of magmatic-
dominated fluids [2]. The variations in tourmaline composition are interpreted to reflect a
combination of cooling and changes from wallrock- to fluid-dominated conditions.
[1] Kelly and Rye (1979) Econ. Geol. 74: 1721-1822.
[2] Foxford et al. (2000) J. Struct. Geol. 22:1065-1086.
12
Alluvial-fan terraces as strain markers for Quaternary contractile
deformation in the interior of the southern Central Andes:
Intermontane alluvial basin fills in the Calchaquí Valley of the Eastern
Cordillera (Cachi-Payogasta area), NW Argentina (25°03’S, 66°07’W)
Leonardo E. Escalante1, Manfred R. Strecker2, Fernando D. Hongn1.
1Instituto de Bio y Geociencias del Noroeste Argentino (IBIGEO), Consejo Nacional de
Investigaciones Científicas y Técnicas (CONICET)-Universidad Nacional de Salta (UNSA), 9
de Julio 14, 4405 Rosario de Lerma, Salta, Argentina.
2Institut für Erd- und Umweltwissenschaften, Universität Potsdam, Karl-Liebknecht-Straße 24,
14476 Potsdam, Germany.
The E Cordillera of the southern Central Andes in NW Argentina is characterized by
intermontane basins flanked by reverse-fault bounded ranges. The basins are located in the
interior parts of the orogen and straddle the eastern boundary of the high-elevation intra-
orogenic Andean Plateau. One of the largest intermontane basins is the N-S oriented
Calchaqui Valley. In its northernmost sector the valley is bounded by E and W-dipping reverse
faults, respectively. The basin exposes deformed Tertiary strata that are unconformably
overlain by Quaternary conglomerates that are part of coalesced alluvial fans. This sector of
the valley narrows considerably and neotectonic activity in this area has been thought to be
associated with the range-bounding faults. In addition, it has been proposed that the main
Quaternary faults reflect the reactivation of Tertiary structures. The effects of Quaternary
deformation in this area are recorded by faults, folds, unconformities, and cataclasized and
tilted conglomerates. In addition, changes in paleocurrents and provenance, anomalies in the
drainage network, and convex longitudinal stream profiles unambiguously demonstrate the
impact of Quaternary tectonic activity in the Calchaqui Valley. Taken together, available
sedimentological, geomorphological, and structural information as well as historical and
instrumental seismicity data show that the northern sector of the Calchaquíes Valley has been
actively deforming during the Quaternary. This emphasizes the need to perform additional
systematic investigations of the characteristics of the Quaternary deposits and their tectonic
overprint at regional scale to help understand the spatiotemporal evolution of tectonic
processes in light of ongoing contraction and potential hazards.
13
Holocene Tectonic Deformation Processes in the Transition between
Sierras Pampeanas and Eastern Cordillera, Cafayate Valley (26°00’ –
25°50’LAT., 66°00’-65°50’LONG.),Salta
Sara Figueroa Villegas, Escalante Leonardo1, Hongn Fernando1, Strecker Manfred R. 2
1 Instituto de Bio y Geociencias del NOA (UNSa-CONICET). 9 de Julio 4, Rosario de Lerma.
2 Institut fürr Erd- und Umweltwissenschaften, Universität Potsdam, D-14476 Potsdam,
Alemania
The Quaternary deformation in Cafayate valley has been documented, near to Quebrada La
Yesera, mainly as sinsedymentary structures in Cafayate-Santa María paleolake. (13,830
years BP. until 4800 years BP). In this work it has been described the deformation that affect
the fluvio-aluvial Quaternary deposits as well as Cafayate-Santa María paleolake deposits in
the piedmont of Sierra de León Muerto. This range is bounded by the E-dipping Castillo Fault.
The structures that affect the Quaternary deposits are reverse faults that has been interpreted
as splay faults (footwall shortcut) of the Castillo Fault that generated thrust folds. Our new data
documents sustained Holocene shortening in this structurally complex region.
14
A simple and inexpensive technique for assessing contamination
during drilling operations
André Friese1, Jens Kallmeyer1, Jan Axel Kitte1, Edgar Kutschera1, Ivan Montaño Martínez2,
Satria Bijaksana3, Dirk Wagner1, the ICDP Lake Chalco Drilling Science Team and the ICDP
Towuti Drilling Science Team
1 GFZ German Research Centre For Geosciences, Section 5.3. Geomicrobiology, 14473
Potsdam, Germany
2 Laboratorio de Paleolimnologia, Instituto de Geofísica, UNAM, Mexico
3 Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Indonesia
Exploration of subsurface environments relies on drilling, which inevitably causes infiltration of
drilling fluids, containing non-indigenous microbes from the surface, into the core. It is of
paramount importance to assess the degree of contamination to identify uncontaminated
samples for geomicrobiological investigations. To do this, a tracer is mixed into the drilling fluid,
usually dissolved gasses like Perfluorocarbon or microbe-sized fluorescent particles
(microspheres). For microspheres the main problem was the high price, which limited their use
to spot checks or small drilling operations.
We developed a modified microsphere tracer approach using an aqueous fluorescent pigment
dispersion, that costs four orders of magnitude less, allowing for a liberal use even in large
drilling operations. Its suitability was successfully tested at two ICDP Drilling campaigns at
Lake Towuti, Indonesia and at Lake Chalco, Mexico.
Contamination can be detected by fluorescence microscopy or by flow cytometry at a
sensitivity that is in the range of established techniques. By using a small portable cytometer,
high-resolution data can be obtained directly on-site with minimal effort. Also, the tracer is
stable and can be detected long after core retrieval. Therefore this approach offers an
inexpensive but powerful alternative technique for contamination assessment for future drilling
campaigns.
15
3D structure and conductive thermal field of the sea of Marmara
Ershad Gholamrezaie (1,2), Magdalena Scheck-Wenderoth (2,3), and Oliver Heidbach (2)
(1) University of Potsdam, Potsdam, Germany
(2) Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Potsdam,
Germany
(3) RWTH Aachen University, Aachen, Germany
The Sea of Marmara and its basins mainly evolved due to the activities of the Thrace-Eskisehir
Fault Zone (TEFZ) in Neogene and the North Anatolian Fault Zone (NAFZ) in Quaternary. At
present-day, the Sea of Marmara is still evolving due to the NAFZ and the Marmara region is
an earthquake danger zone while hosting around 20 million of inhabitants. For a better
understanding of the tectonic processes and geodynamics evolution, it is important to model
the geological structure and the thermal field of this region. The aim of this study is to build a
3D lithospheric-scale structural model and a 3D conductive thermal model for the Sea of
Marmara and including its adjacent onshore areas. Therefore, we integrate different geological
and geophysical data such as existing structural models, well data, seismic observations and
gravity to build a new 3D lithospheric-scale structural model which is additionally constrained
by 3D gravity modelling. The final 3D structural model differentiates various sedimentary,
crustal and mantle units and is the base for the 3D thermal field calculation. The 3D conductive
thermal model is a numerical solution to the Fourier’s law equation in steady-state condition
and considering the thermal properties of the corresponding structural model. Our 3D
lithospheric-scale models of the geological structure and the conductive thermal field are the
key points for further general research and useful particularly for mechanical modelling,
considering variations in rheology and strength of the lithosphere in the Marmara region. In
addition, our results have application in geo-resources exploration and would be helpful in risk
management and hazard mitigation.
16
Lithosphere-scale 3D gravity and thermal modeling of the Central
Andes
Federico Ibarra
We developed a lithosphere-scale 3D thermal model of the Central Andes between 20-30ºS
and 76-61ºW. The aim of this work is to investigate the thermal state of the region and
characterize its anomalies. The thermal calculations are based on the assumption that the heat
is transported mainly by conduction in the lithosphere using the finite element method. The
lithospheric structure on which the calculations were made is taken from a previous 3D density
model, simplified and updated with new published data and constrained by forward modelling
of the Bouguer anomaly. Six thermal fields were calculated using different boundary
conditions, keeping one of them as the final model. The resulting thermal field shows
anomalies consistent with the location of low velocity zones, and the temperature is also high
enough to produce partial melt in the crust. This is the first 3D thermal model developed for
the region and it will contribute to understand and quantify geological and geodynamical
processes.
17
Quantification of ore-forming processes in magmatic hydrothermal
Sn-W systems: a fluid inclusion study of the Zinnwald deposit
Maximilian Korges1, Philipp Weis1, Volker Lüders1, Oscar Laurent2
1GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany
2Institute of Geochemistry and Petrology ETH Zürich, Clausiusstrasse 25, Zürich, Switzerland
The Sn-W-Li deposit in the roof zone of the Zinnwald granite is associated with Sn-bearing
greisen and sub-horizontal veins containing economical contents of cassiterite and wolframite.
The relation between the contrasting mineralizations remains elusive. We analysed fluid
inclusions from samples of the German part of the deposit using conventional, infrared-
microthermometry and LA-ICP-MS.
The most common primary FI in the quartz veins show homogenization temperatures (Th)
between 360°C and 380°C and high variability in salinity (1–8 eq.w(NaCl)). IR
microthermometry of FI in ore from the vein reveal lower Th but higher salinities (12
eq.w(NaCl)). In contrast FIA in greisen have similar Th (360–380°C) to the vein quartz and
salinities between 5 and 8 eq. w(NaCl). Few quartz vein samples contain boiling assemblages
of brine (up to 35 eq.w(NaCl)) and vapor-rich inclusions (Th = 300-340°C)
LA-ICP-MS data show that all elements required for forming a Sn-W deposit are included in
the hydrothermal fluid. The results suggest that ore formation is controlled by two processes:
1) fluid rock interaction during greisen formation and 2) boiling and the loss of HCl leading to
ore precipitation in the veins, which are interpreted as former fluid pathways in the peripheral
parts of the granite.
18
Influence of the orogenic lithospheric strength on the deformation of
the foreland upper crust
Sibiao Liu1,2, Stephan V. Sobolev 1,2, Andrey Y. Babeyko 1, Frank Krüger 2, Javier Quinteros 1
and Anton Popov 3
1 German Research Center for Geosciences GFZ, Potsdam, Germany
2 Institute of Earth and Environmental Science, University of Potsdam, Potsdam, Germany
3 Institute of Geosciences, Johannes Gutenberg University Mainz, Mainz, Germany
In the Central Andes, the Altiplano-Puna Plateau was formed with a pronounced N-S oriented
deformation diversity including a broad thin-skinned Sub-Andean thrust belt in Altiplano and
the thick-skinned deformation in the Santa Barbara system in south Puna foreland. The
mechanism of different deformation patterns in the orogenic foreland remain controversial.
Previous studies suggested that they might be controlled by strength variations of the
lithosphere in which the lithospherical and crustal thickness, the thermal regime, as well as
sedimentary loads and their strength play an important role. Here we use high-resolution
numerical models to investigate these factors controlling mechanical and thermal strength of
the lithosphere. Our model results demonstrate that the first prerequisite for thin-skinned
deformation in the foreland sediment cover is internal weak sedimentary rocks due to high pore
fluid pressure. With the friction drop of foreland sediments, the simple shear shortening
accompanied by thin-skinned thrusting at the uppermost crust of foreland is formed by the
weakening of the orogenic lithosphere by either thickening the crust or thinning the entire
lithosphere. The deformation shifts from thin-skinned to thick-skinned structure in the foreland
uppermost crust when the orogenic lithosphere is getting stronger due to the cold and thick
lithosphere or the weak sediment cover above the foreland is absent. In addition, the transition
from compression to extension on top of the orogen is controlled by the intensity of sediments
weakening.
19
REE variations in the pre-Andean crustal basement: Enrichment in a shear zone
of Ordovician granitoids and mineralization in a fenitized Devonian
monzogranite, Eastern Sierras Pampeanas
Melanie Lorenz1 , Uwe Altenberger1, Robert Trumbull2 ,Raúl Lira3 , Monica López de Luchi 4,
Nicolas Viñas5, José Pablo Lopez6
1 University of Potsdam
2 GFZ Potsdam
3 University of Córdoba
4 University of Buenos Aires
5 Michelotti e hijos Córdoba
6 University of Tucuman
In the light of an increasing demand for high-tech elements like rare earth elements
for the globa markets, this study focuses on obtaining knowledge about the genesis
of their primary deposit and secondary enrichment processes.
An unusual REE-bearing assemblage was identified in a hydrothermally altered
(fenitized) biotite-monzogranite at Rodeo de Los Molles, which is part of the
Devonian Las Chacras-Piedras Coloradas Batholith in San Luis province, Eastern
Sierras Pampeanas. The fenitization occurs in an elliptical, NNE-SSW trending zone
that may be fault-related. Fenitization is characterized by metasomatic gain of Na
and K as well as loss of Ca and Sr. The fenitized zone is locally enriched in light
rare earth elements (LREE) and has been subject to a mineral exploration
campaign (Lira et al., 1999). Drill-core samples from that campaign and new surface
samples are the basis for the present investigation, which aims to decipher the fluid
evolution and REE-mineralization.
In the Sierras de Paiman, an Ordovician mountain range in the north-west of the
Eastern Sierras Pampeanas, a one kilometer long strain profile along a mylonitic
shear zone was sampled. Fluid-rock interaction during shear zone evolution is
commonly associated with strongly channelized fluids as well as changes in element
chemistry. The mobility of fluid mobile elements like LREE is controlled by the
stability of minerals in which they are incorporated in as well as by the nature of
infiltrating fluids, which forms another focus of this study.
20
Pore Type Characterization and Detection of Effective Pore Network
with Digital Image Analysis: A case study from Miocene Lacustrine
Carbonates (Southern Germany)
Sven Maerz
University of Potsdam, Institute of Earth and Environmental Science, Potsdam, Germany
In addition to routine porosity and permeability measurements, the application of Digital Image
Analysis (DIA) results in quantitative data of pore geometry, which is the main factor controlling
petrophysical properties in a sedimentary rock. In this study, these DIA-derived data are
utilized to characterize each occurring pore type and to detect the most effective pore types
which form an interconnected pore network and therefore determine permeability. We provide
a step by step workflow of a new approach based on DIA, performed on 76 samples of marginal
lacustrine carbonates from the northern lake margin of the Miocene Nördlinger Ries crater lake
in Southern Germany. This method comprises four main steps, each providing multi-scale
information to characterize each individual pore, each pore type and the entire pore system.
Since each pore type is confined by the sedimentary fabric and linked to a distinct genetic
process, results can be transferred to recent and ancient analogues settings, and complement
to diagenetic studies of the paragenetic history of the pore-hosting sedimentary rock. As a
result, the extraction of the interconnected (or effective) pore network leads to an improved
correlation between porosity and permeability which eases the often difficult prediction of both
petrophysical parameters in carbonates.
21
Astronomical forcing of Eocene monsoons
Niels Meijer1,2, Hemmo Abels3, Mustafa Kaya1,2, Pierrick Roperch2, Alexis Licht4, Rik Tjallingii5,
Yang Zhang6, Zhaojie Guo6, Zhongping Lai7, Guillaume Dupont-Nivet1,2,6
1) Institute of Earth and Environmental Sciences, Universität Potsdam, Germany.
2) Géosciences Rennes, UMR CNRS 6118, Université de Rennes, France.
3) Department of Geosciences and Engineering, Delft University of Technology, The
Netherlands.
4) Department of Earth and Space Sciences, University of Washington, USA.
5) Section 5.2: Climate Dynamics and Landscape Evolution, GFZ German Research Centre for
Geosciences, Germany.
6) Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, Beijing,
China.
7) School of Earth Sciences, China University of Geosciences, Wuhan, China.
Monsoons are the major source of moisture for central Asia but their dynamics remain poorly
understood. To provide insight in their driving forces we focus on early monsoonal records
during the transition from a greenhouse to an icehouse world, as a part of the ERC “MAGIC”
project.
The continental mudrocks of the Xining Basin in central China provide a unique opportunity to
study early monsoons because of their relatively continuous deposits from 40 to 15 Ma yielding
reliable records of Earth’s magnetic reversals and observed astronomically-forced alternations
of monsoonal moisture. This study specifically aims to extend the stratigraphy further back in
time to examine cyclicity in the Early to Middle Eocene.
Magnetostratigraphic analysis of three parallel sections near Xining shows three chrons that
are correlated to C20, C21 and C22. The lithostratigraphy shows dry mudrocks alternating with
wetter fluvio-lacustrine intervals in regular 10-12 meter cycles. These cycles are paced by the
405 kyr eccentricity cycles according to the age model, with lacustrine facies occurring in
eccentricity maxima. This indicates astronomically-forced monsoons at this time. Towards the
Late Eocene the lacustrine intervals become increasingly gypsiferous and the cyclicity
disappears. This has been linked to the 4th Paratethys sea incursion supplying moisture via
the westerlies.
22
Extending Theis’ solution to incorporate heterogeneity into pumping
test analysis
Sebastian Müller (1,2), Alraune Zech (1), Carsten Leven (3), Falk Heße (1), Peter Dietrich (1,3),
Sabine Attinger (1,2)
(1) Helmholtz Centre for Environmental Research - UFZ
(2) Institute of Earth and Environmental Sciences, University of Potsdam
(3) Center for Applied Geoscience, University of Tübingen
A framework for interpreting transient pumping tests in heterogeneous transmissivity fields is
developed to infer the overall geostatistical parameters of the medium without reconstructing
the specific heterogeneous structure point wise. This method is applied to the field sites
“Horkheimer Insel” and “Lauswiesen” (South- West Germany) to estimate the respective
parameters of heterogeneity from pumping test data of each site. The methodology is based
on the upscaling approach Radial Coarse Graining which is applied to deduce an effective
radial description of multi-Gaussian transmissivity. It was used to derive an Effective Well Flow
Solution for transient flow conditions including not only the storativity, but also the geometric
mean, the variance, and the correlation length of log-transmissivity. This solution is shown to
be appropriate to characterize the pumping test drawdown behavior in heterogeneous
transmissivity fields making use of ensembles of simulated pumping tests with multiple
combinations of statistical parameters. The whole procedure is described in detail in Zech et
al. 2016 (doi: 10.1002/2015WR018509).
23
Revision of earthquake hypocentre locations in global bulletin data
sets using source-specific station terms
Nima Nooshiri
Global earthquake locations are often associated with very large systematic travel-time
residuals even for clear arrivals, especially for regional and near-regional stations in
subduction zones because of their strongly heterogeneous velocity structure. Travel-time
corrections can drastically reduce travel-time residuals at regional stations and, in
consequence, improve the relative location accuracy. We have extended the shrinking-box
source-specific station terms technique to regional and teleseismic distances and adopted the
algorithm for probabilistic, nonlinear, global-search location. We evaluated the potential of the
method to compute precise relative hypocentre locations on a global scale. The method has
been applied to two specific test regions using existing P- and pP-phase picks. The first data
set consists of 3103 events along the Chilean margin and the second one comprises 1680
earthquakes in the Tonga-Fiji subduction zone. Pick data were obtained from the GEOFON
earthquake bulletin, produced using data from all available, global station networks. A set of
timing corrections varying as a function of source position was calculated for each seismic
station. In this way, we could correct the systematic errors introduced into the locations by the
inaccuracies in the assumed velocity structure without explicitly solving for a velocity model.
Residual statistics show that the median absolute deviation of the travel-time residuals is
reduced by 40–60 per cent at regional distances, where the velocity anomalies are strong.
Moreover, the spread of the travel-time residuals decreased by ∼20 per cent at teleseismic
distances (>28◦). Furthermore, strong variations in initial residuals as a function of recording
distance are smoothed out in the final residuals. The relocated catalogs exhibit less scattered
locations in depth and sharper images of the seismicity associated with the subducting slabs.
Comparison with a high-resolution local catalog reveals that our relocation process
significantly improves the hypocentre locations compared to standard locations.
24
Identifying Typhoon Tracks based on Event Synchronization derived
Spatially Embedded Climate Networks
Ugur Ozturk1,2, Norbert Marwan1, Jürgen Kurths1,3
1Potsdam Institute for Climate Impact Research, Potsdam, Germany
2Institute of Earth and Environmental Science, University of Potsdam, Potsdam, Germany
3Department of Physics, Humboldt University, Berlin, Germany
Complex networks are commonly used for investigating spatiotemporal dynamics of complex
systems, e.g. extreme rainfall. Especially directed networks are very effective tools in
identifying climatic patterns on spatially embedded networks. They can capture the network
flux, so as the principal dynamics of spreading significant phenomena. Network measures,
such as network divergence, bare the source-receptor relation of the directed networks.
However, it is still a challenge how to catch fast evolving atmospheric events, i.e. typhoons.
In this study, we propose a new technique, namely Radial Ranks, to detect the general pattern
of typhoons forward direction based on the strength parameter of the event synchronization
over Japan. We suggest to subset a circular zone of high correlation around the selected grid
based on the strength parameter. Radial sums of the strength parameter along vectors within
this zone, radial ranks are measured for potential directions, which allows us to trace the
network flux over long distances. We employed also the delay parameter of event
synchronization to identify and separate the frontal storms' and typhoons' individual behaviors.
25
High-resolution reconstruction of past climate and environment from
lacustrine deposits in NW Argentina
Joan Pascual-Montañés
The lake-complex Lagunas de Yala (24°06’S, 65° 29’W, NW Argentina) is located along the
slope of the Eastern Cordillera (EC) in the Central Andes. The high topography blocks moisture
from equatorial latitudes and defines an abrupt precipitation gradient from the humid EC foothill
and Chaco foreland basin to the arid Puna Plateau. For this work, an 82cm long surface core
from Comedero Lake (24°06’50”S, 65°29’03”W, 2026m above sea level) was analyzed.
According to geochemical data and microfacies analysis, five different facies have been
identified along the core, and the lithology for every facies has been established. Among them,
extreme events layers have been identified along the complete record. Wood and leaf remains
have dated the lowermost sediments to 600yr cal. BP. Micro-XRF data, organic matter analysis
and microfacies observation show the potential of the Yala Lakes sedimentary sequence as a
high-resolution archive of environmental and climate change in the tropical Andes and will
provide crucial information of the evolution of the South America Monsoon System (SAMS)
during the mid-late Holocene. Identifying and understanding extreme events and climate
variability recorded in Comedero Lake sediments provide essential knowledge for predicting
future climate change and managing resources in this region.
26
Rock Glacier Response to Climate Change
Julia Pommerencke (1), Oliver Korup (1), Stella Moreiras (2)
(1) University of Potsdam, Institute of Earth and Environmental Science, Potsdam, Germany
(2) Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales, Mendoza, Argentina
Rock glaciers are bodies of frozen debris and ice that move under the influence of gravity in
permafrost areas. They play an important role as potential prime mover of the Central Andean
sediment cascade. Using temperature and precipitation data from the global climate model
(CCSM 4) from the WorldClim dataset, rock glacier response under different climate scenarios
were analysed for upper Atuel River catchment, south of Mendoza Province (Argentina). Rock
glaciers are traditionally viewed as diagnostic of sporadic alpine permafrost. Their tongues are
often near the annual mean 0°C isotherm located.
Rock glaciers in Atuel River are sensitive to changes in temperature, and may change in
activity and abundance. Where active rock glaciers become inactive their coarse material,
which was bounded by ice, will be released into the sediment cascade.
27
Digital topography for geomorphology and beyond: frontiers in
meters to sub-meter resolution remote sensing
Ben Purinton
Since the flight of the Shuttle Radar Topography Mission (SRTM) in February 2000 the
geoscience community has benefited from rapid improvements in the coverage and quality of
digital elevation models (DEMs). Most recently the 12 m resolution TanDEM-X DEM was
released by DLR for research purposes, with many submitting successful proposals to attain
this cutting edge dataset. Additionally, there now exists a plethora of open-access, commercial,
and research agreement DEMs, both as edited products and raw data for manual processing,
at resolutions of 1-10 m. Many of these datasets are derived from satellite sensors, which
provide wide-coverage in remote regions of geologic interest. Importantly, many geologists
utilizing DEMs to quantify changes in topography do so without rigorous accuracy
assessments that include not only vertical and horizontal elevation errors, but also the effect
of various sensor types (e.g., radar versus optical) and platforms (e.g., SRTM versus TanDEM-
X) on key derivatives of elevation, such as slope and curvature. In this PhD work we seek to
test the quality of satellite derived (and drone/lidar) DEMs across a range of scales, from
individual catchments to entire mountain ranges, in order to provide a fuller assessment of
DEM applicability for the calculation of geomorphic metrics. This work has already begun with
a comparison of DEMs from the SRTM, ASTER, TanDEM, and ALOS missions in northwestern
Argentina on the Puna Plateau. Here we assessed vertical accuracy by comparing standard
deviations of DEM elevation versus 307,509 differential GPS measurements, followed by
channel profile analysis of m/n values, a comparison of slope and curvature distributions, and
a 2D Fourier analysis of high-frequency noise in the DEMs. Ongoing work involves the
comparison of the SRTM and TanDEM-X DEMs for elevation differencing, accounting for
systematic biases between the datasets. This work is applicable not only to geomorphologists,
but also to glaciologists interested in using these DEMs for glacier mass-balances. Future PhD
work will include the use of lidar and drones to create dense 3D point clouds. In combination
with satellite data, these point clouds will be used to bridge the gap between individual plots
and catchment-scale geomorphology and to answer questions related to fine-scale variability
in hillslope and channel morphology related to climatic, tectonic, lithologic, and biologic
forcings.
28
Terrain Controls on the Occurrence of Coastal Retrogressive Thaw
Slumps along the Yukon Coast, Canada
Justine Ramage
Retrogressive thaw slumps (RTSs) are among the most active landforms in the Arctic; their
number has increased significantly over the past decades. While processes initiating discrete
RTSs are well defined, the major terrain controls on the development of coastal RTSs at a
regional scale remain unrevealed. Our research brings new insights into the dynamics
of coastal RTSs. We reveal the main geomorphic factors that determine the development of
RTSs along a 238 km coastal segment of the Yukon Coastal Plain, Canada. We 1) show the
current extent of RTSs, 2) ascertain the factors controlling their activity and initiation, and 3)
explain the differences in the density and areal coverage of RTSs. We mapped and classified
287 RTSs using high-resolution satellite images acquired in 2011. We highlighted the main
terrain controls over their development using univariate regression trees. Both activity and
initiation of RTSs were influenced by coastal geomorphology: active RTSs and RTSs initiated
after 1972 occurred primarily on terrains with slope angles greater than 3.9° and 5.9°,
respectively. The density and coverage of RTSs were constrained by the volume and thickness
of massive ice bodies. Differences in coastal erosion rates along the coast did not affect the
model. We infer that coastal erosion rates averaged over a 39-year period are unable to reflect
the complex relationship between RTSs and coastline dynamics. We emphasize the need for
large-scale studies of RTSs – to evaluate their impact on the ecosystem and to measure their
contribution to the global carbon budget.
29
Determining hydroclimatic extreme events over the south-central
Andes
Maryam Ramezani Ziarani (1,2), Bodo Bookhagen (1), Torsten Schmidt (2), Jens Wickert (2,3),
Alejandro de laTorre (4), and Jan Volkholz (5)
(1) University of Potsdam, Potsdam, Germany
(2) GFZ German Research Centre for Geosciences, Potsdam, Germany
(3) Technische Universität Berlin, Berlin, Germany
(4) Austral University, Buenos Aires, Argentina
(5) Potsdam Institute for Climate Impact Research (PIK), Potsdam,Germany
The south-central Andes in NW Argentina are characterized by a strong rainfall asymmetry. In
the east-west direction exists one of the steepest rainfall gradients on Earth, resulting from the
large topographic differences in this region. In addition, in the north-south direction the rainfall
intensity varies as the climatic regime shifts from the tropical central Andes to the subtropical
south-central Andes. In this study, we investigate hydroclimatic extreme events over the south-
central Andes using ERA-Interim reanalysis data of the ECMWF (European Centre for
Medium-Range Weather Forecasts), the high resolution regional climate model (COSMO-
CLM) data and TRMM (Tropical Rainfall Measuring Mission) data. We divide the area in three
different study regions based on elevation: The high-elevation Altiplano-Puna plateau, an
intermediate area characterized by intramontane basins, and the foreland area. We analyze
the correlations between climatic variables, such as specific humidity, zonal wind
component, meridional wind component and extreme rainfall events in all three domains. The
results show that there is a high positive temporal correlation between extreme rainfall events
(90th and 99th percentile rainfall) and extreme specific humidity events (90th and 99th
percentile specific humidity). In addition, the temporal variations analysis represents a trend of
increasing specific humidity with time during time period (1994-2013) over the Altiplano-Puna
plateau which is in agreement with rainfall trend. Regarding zonal winds, our results indicate
that 99th percentile rainfall events over the Altiplano-Puna plateau coincide temporally with
strong easterly winds from intermountain and foreland regions in the east. In addition, the
results regarding the meridional wind component represent strong northerly winds in the
foreland region coincide temporally with 99th percentile rainfall over the Altiplano-Puna
plateau.
30
Organofacies of the Yacoraite Formation, Salta Basin; Argentina
Ricardo Ruiz
The Yacoraite Formation (Maastrichtian-Danian), of the middle Balbuena Subgroup, has been
identified as the main oil-source rock in NW Argentina in the Salta Rift Basin. It was deposited
immediately following Lower Cretaceous rifting, and represents the last Cretaceous marine
ingression (Marquillas et al, 2007) although some evidences have also been found for a
lacustrine setting in some areas (Terra et al., 2012; Schmidt et al, 2017). Depending on its
depositional environment, this formation exhibits wide ranges of organic content from poor up
to rich (up to 6% TOC) and I - II kerogen types (Stinco and Barredo, 2014). The biggest oil
field is Caimancito where light oil (42º API) is produced. In this work rock-eval pyrolysis results
are shown to preliminary assess oil potential and it´s depositional environment of Metán-
Alemanía (M-A) and Tres Cruces (TC) sub-basins.
31
Testing long-term controls of sedimentary basin architecture. Tres
Cruces Subbasin, Jujuy, Argentina
Wera Schmidt (1), Claudia Galli (2,3), Maria Mutti (1)
1 University of Potsdam, Potsdam, Germany
2 Universidad Nacional de Jujuy, Argentina
3 Universidad Nacional de Salta, Argentina
Concepts of reciprocal sedimentation link the vertical alternation of clastics and carbonates
and their lateral continuity in shallow-marine environments with relative sea-level changes.
Mixed, clastic-carbonate strata of the Maastrichtian to Danian Yacoraite Formation (Salta
Group) provide an ideal setting to test how the concept of reciprocal sedimentation can be
applied in a syn- and post-rift basin with significant lateral and vertical facies heterogeneity.
Focus of this study is the Tres Cruces subbasin. The Tres Cruces subbasin is the northern
extent of the triradiate Salta basin (NW Argentina). A total of 14 stratigraphic sections have
been measured along two regional transects. The physical correlation of the facies packages,
integrated with petrographic, geochemical and biosedimentary analyses, provide a tool to
visualize how facies and sedimentary architecture change throughout the Tres Cruces
subbasin.
The spatial superposition of lithofacies at basin-scale indicate a longer-term control by relative
sea-level changes. However, observations at the outcrop scale suggest that a locally
heterogeneous facies distribution is governed by environmental changes. Hence, concepts of
reciprocal sedimentation must be applied with care in spatially complex rift basins, because
environmental conditions may locally overrun regional stratigraphic patterns.
32
Interaction between small scale landscape structure and erosive
wind events in La Pampa, Argentina
Nicole Siegmund
The landscape of the semiarid Pampa in central Argentina is characterized by glacial aeolian
depositions (loess) leaving large planes with sporadic dune structures. Since the land use
change from pasture to arable land, the upper soil is exposed to frequent and strong wind
events. How far the old structures influence the recent erosion processes by wind was
investigated on a sandy measuring field in the province La Pampa. This study is focused on
the inter-relationships between small topographic characteristics and wind erosion of different
directions at the plot scale. To investigate the spatial variability of mass-transport by saltation
18 Modified Wilson and Cook (MWAC) were installed on a 1.44 ha large field in a 20 x 40 m
grid. Seven storms from three different wind directions were analyzed. Physical and chemical
soil properties from the upper soil as well as a digital elevation model were recorded in a 20 x
20 m grid. The spatial high resolute analysis of the soil properties and the aeolian transport
processes allows conclusions about the individual pattern of erosion and deposition for each
storm.
It can be shown that erosion occurs on exposed and luv and deposition on sink and lee terrain
positions. Furthermore, a multiple regression model is build, explaining up to 90% of the
variance of erosion by just using four predictors: topsoil thickness, relative elevation, carbon
content and slope direction. Our findings suggest a structure-process-structure complex where
the ancient dune structure determines the recent wind erosion and the ongoing erosion
process can lead to an increase of the soil heterogenity.
33
Mountain rivers may need centuries to adjust to earthquake-
triggered sediment pulses, Pokhara, Nepal
Amelie Stolle (1), Oliver Korup (1), Wolfgang Schwanghart (1), Anne Bernhardt (2), Basanta Raj
Adhikari (3), Christoff Andermann (4), Hella Wittmann (4), Silke Merchel (5)
1Institute of Earth and Environmental Sciences, University of Potsdam, Germany
2Institute of Geological Sciences, Freie Universität Berlin, Malteserstr. 74-100, 12249 Berlin,
Germany
3Institute of Engineering, Tribhuvan University, Kathmandu, Nepal
4Helmholtz-Zentrum Potsdam, German Centre for Geosciences GFZ, Germany
5Helmholtz-Zentrum Dresden-Rossendorf, Helmholtz Institute Freiberg for Resource
Technology, Dresden, Germany
Mountain rivers respond to strong earthquakes by rapidly aggrading to accommodate excess
sediment delivered by co- and post-seismic landslides. Detailed sediment budgets suggest
that it takes rivers several years to decades to recover from such seismic disturbances,
depending on how recovery is defined. We test this notion and study how rivers adjusted to
catastrophic sedimentation triggered by at least three medieval earthquakes in the central
Nepal Himalaya. Rapid aggradation formed a large fan in the Pokhara Valley covering 148 km2
of mountainous terrain. A robust radiocarbon chronology provides an ideal framework for
gauging average rates of fluvial incision and adjustment. We use high-resolution digital
elevation data, geodetic field surveys, and historic aerial photos documenting channel
changes. We estimated removed volumes, use long-term denudation rates, clasts counts and
several re-exhumed tree trunks in growth position as proxies to define whether the river system
is adjusted since medieval times. We find sediment yields of up to 4200 t km–2 yr–1 that greatly
exceed the density-adjusted background rates of 10Be catchment-wide denudation. The
lithological composition of active river banks differs from local bedrock and confirms that rivers
are still excavating medieval deposits. Pronounced knickpoints at tributary junctions add to the
picture of a drawn-out fluvial response, while the re-exhumed tree trunks indicate that terraces
at tributary margins have been incised to near their base. Our results challenge the notion that
mountain rivers recover within years or decades. The Pokhara Valley document that even
highly erosive Himalayan rivers may need centuries to millennia to adjust. Our results may
motivate some rethinking of post-seismic hazard appraisals and infrastructural planning during
the rehabilitation phase in earthquake-struck regions.
34
Defining moisture sources and organic matter transport processes
in the NW Himalaya
Iris van der Veen
δ2H and d18O values of surface waters provide information on snowmelt time and magnitude,
moisture sources and evapotranspiration processes. Increased rates of glacial/snow melt not
only increase river discharge and flood potential, but also the temporal heterogeneity in river
discharge. This study focuses on the western Himalaya where moisture originates
predominantly from the Indian summer monsoon, while higher elevation catchments receive
precipitation from the Westerly Disturbances. δ2H in both the Sutlej and Alaknanda transects
show a significant negative correlation with mean catchment elevation, which is mainly caused
by Rayleigh fractionation in progressive rainout during orographic uplift, and cooling of moist
air masses. Second, a 6-25% increase in d-excess during peak snowmelt season, and a
decrease in snow cover from >90% in winter to <30% in summer indicates substantial input of
snow/ice melt into surface waters of high-elevation catchments. The time series shows a
relationship between spring snowmelt and surface water d-excess values. These results
suggest that snowmelt in high elevation catchments can alter surface water isotopic content,
and can be used as a tracer for snow/ice meltwater. Additionally, we use compound specific
stable isotopes (δ2H) and GDGTs along four altitudinal gradients, to investigate the impact of
environmental factors on δ2H and brGDGTs. These transects have varying precipitation
regimes, relative influences of moisture sources and vegetation. Combining this multi proxy
study with satellite derived root-zone soil moisture content and TRMM-derived precipitation,
we strive to identify the controlling secondary factors that complicate the relationship between
source water δ2H and soil alkane δ2H.
35
Numerical homogenization approach for coupling of chemical and
mechanical processes in the geological subsurface
Wetzel, Maria; Kempka, Thomas; Kühn, Michael
Reactive transport and related processes as dissolution and precipitation of minerals may
substantially change rock composition, and consequently its geomechanical properties.
However, this chemo-mechanical interaction is rarely considered in assessments of
subsurface processes. An approach to determine the macroscopic stress-strain-relationship of
a composite material, based on the mechanical characteristics of its constituents is provided
by analytical homogenization models. This method is widely used within the field of materials
sciences and highly promising for geoscientific applications. However, none of the analytical
models can accurately determinate elastic parameters of the composite for the entire range of
the inclusions mechanical properties, their specific volume fractions and aspect ratios.
Numerical 3D models allow for a more precise quantification and help to overcome the
limitations of analytical solutions, especially regarding the spatial distribution of inclusions and
their interaction. For a representative rock volume element, effective elastic properties are
determined in our approach by taking into account the characteristic geomechanical
parameters of all relevant mineral inclusions. We successfully validated our model against
available analytical solutions and published experimental data. Sensitivity analyses indicate
that the calculated elastic rock properties vary up to 28 % due to the spatial distribution of the
inclusions within the rock matrix. Additionally, the developed numerical homogenization
method enables an improved quantification of rock parameters: particularly for high inclusion-
to-matrix-volume fractions and high mechanical property contrasts, the analytical solution
deviates up to 58 % from the numerical results. In conclusion, the introduced homogenization
approach provides an essential basis for coupling chemical and mechanical processes in
numerical simulations related to the geological subsurface.