Conference Agenda

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Session Overview
Session
Poster session for Topic: 16.1
Time:
Tuesday, 21/Sept/2021:
6:00pm - 6:45pm


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Presentations

Drilling overdeepened (Eastern) Alpine Valleys and Basins

Markus Fiebig1, Flavio Anselmetti2, Marius Büchi2, Gerald Gabriel3, Ernst Kroemer4, Frank Preusser5, Jürgen Reitner6, Sebastian Schaller2, Bennet Schuster2, David Tanner3, Ulrike Wielandt-Schuster7

1University of Natural Resources and Life Sciences, Austria; 2University of Berne, Switzerland; 3Leibnitz Institute for Applied Geophysics (LIAG), Germany; 4Bavarian Environment Agency, Germany; 5Albert-Ludwigs-Univeristy, Germany; 6Geological Survey of Austria; 7Regierungspräsidium Freiburg, Germany

The panalpine project "DOVE" (Drilling Overdeepened Alpine Valleys), co-funded by the International Continental Scientific Drilling Program (ICDP), is drilling a series of overdeepened glacial troughs around the Alps that were formed by subglacial erosion during past glaciations.

In the northeastern section of the DOVE project, we (re)investigate the inneralpine basin of Bad Aussee (Traun glacier area, Austria), the subalpine basin of the Salzach Foreland glacier (Neusillersdorf, Bavaria), and the tongue basin area of the Pleistocene Isar-Loisach-Foreland glaciers (Schäftlarn). Depths of the inneralpine glacial erosion below Bad Aussee reach down to –400 m below sea level (the level of the Dead Sea in the Levant, the lowest part of today’s surface topography on Earth). 880 m of core material have been drilled into the basin and will be reinvestigated and physically dated by luminescence and cosmogenic isotopes.

In Neusillersdorf (Bavaria), we continue to study the basin infill of a branch basin of the Salzach Foreland glacier. We know from former dating attempts that sediments from the penultimate glaciation and older are available in the basin.

Finally, the sequence in former tongue basin area of the Isar Loisach Foreland glacier area, close to Munich, offers about 100 m of lake sediments, which are interpreted to contain sediments from Middle Pleistocene glaciations.

All available cores will be studied with state-of-the-art tools and methods in modern sedimentology and dating technics. Especially the combined investigation and interpretation of several drillholes will offer the opportunity to develop a modern reconstruction of past (Eastern) Alpine glacial environments.



Drilling Overdeepened Alpine Valleys: First results from the Tannwald Borehole

Bennet Schuster1, David C. Tanner2, Gerald Gabriel2, Thomas Burschil2, Thomas Wonik2, Frank Preusser1, Flavio Anselmetti3, Marius W. Buechi3, Sebastian Schaller3, Markus Fiebig4, Ulrike Wielandt-Schuster5

1Institute of Earth and Environmental Sciences, University of Freiburg, Germany; 2Leibniz Institute for Applied Geophysics, Hannover, Germany; 3Institute of Geological Sciences, University of Bern, Switzerland; 4University of Natural Resources and Life Sciences, Vienna, Austria; 5Landesamt für Geologie, Rohstoffe und Bergbau, Freiburg, Germany

The panalpine project "DOVE" (Drilling Overdeepened Alpine Valleys), co-funded by the International Continental Scientific Drilling Program (ICDP), is drilling a series of overdeepened glacial troughs around the Alps that were formed by subglacial erosion during past glaciations. The sedimentary fill of these troughs, consisting of multiple stacked and nested glacial sequences, provide the best archives of when and where glaciers reached the Alpine forelands. The combined data from all DOVE sites, comprising synchronous or asynchronous ice advances and ice extents in the different regions, will eventually provide a critical database to evaluate the various patterns in glacial-interglacial paleoclimates and landscape evolution back to the Mid-Pleistocene.

The Tannwald Basin forms a distal, overdeepened part of the Rhine glacial landscape, ca. 50 km north of Lake Constance, and has a maximum depth of 240 m. Core and flush drilling on the western flank of the basin began in April 2021 and reached the bedrock, i.e. top Tertiary Molasse, at a depth of 154 m. The glacial basin is filled by 100 m-thick fine clastics of the Dietmanns Formation (Hosskirchian – Rissian age). This is overlain by 42 m coarse clastics of the Illmensee Formation (Rissian - Wurmian age). We aim to chronologically date the sediments using borehole and core geophysics, OSL, pollen, and noble gases from pore water. Together with detailed sedimentology, these data will be used to constrain the glacial history of the basin. We show the preliminary results of the flush and core drilling, together with the borehole geophysics.



ICDP Project DOVE (Drilling Overdeepened Alpine Valleys): First results from the Basadingen Borehole

Sebastian Schaller1, Flavio Anselmetti1, Marius Büchi1, Markus Fiebig2, Gerald Gabriel3, Ernst Kroemer4, Frank Preusser5, Jürgen Reitner6, Bennet Schuster5, David Tanner3, Ulrike Wielandt-Schuster7

1Institute of Geological Sciences, University of Bern. Switzerland; 2Department of Civil Engeneering and Natural Hazards, University of Natural Resources and Life Sciences Vienna, Austria; 3Department for Seismic, Gravimetry, and Magnetics, Leibniz Institute for Applied Geophysics, Hannover, Germany; 4Bayrisches Landesamt für Umwelt, Augsburg, Germany; 5Institute of Earth and Environmental Sciences, University of Freiburg, Germany; 6Geologische Bundesanstalt für Österreich, Vienna, Austria; 7Landesamt für Geologie, Rohstoffe und Bergbau, Baden-Württemberg, Germany

The panalpine project "DOVE" (Drilling Overdeepened Alpine Valleys), co-funded by the International Continental Scientific Drilling Program (ICDP), is drilling a series of overdeepened glacial troughs around the Alps that were formed by subglacial erosion during past glaciations. The sedimentary fill of these troughs, consisting of multiple stacked and nested glacial sequences, provides the best archives of when and where glaciers reached the Alpine forelands. The combined data from all DOVE sites comprising synchronous or asynchronous ice advances and ice extents in the different regions, will eventually provide a critical database to evaluate the various patterns in glacial-interglacial paleoclimates and landscape evolution back to the Mid-Pleistocene.

One of the DOVE sites drilled the overdeepened Basadingen Trough, located in Northern Switzerland, within the extents of several Middle-Late Pleistocene foreland glaciations of a lobe of the Rheine Glacier. The trough is a narrow, ca. 250-300 m deep structure that runs SSE-NNW, forming a so-far poorly understood, old overdeepened valley system that connected the present-day Thur Valley with the Rhine Valley – a connection that does not exist in the present surface morphology and that was probably only active during the Middle Pleistocene. New high-resolution 2-D seismic displays a detailed seismic stratigraphy with several depositional sequences, indicating that the valley fill consists of deposits from multiple glaciations, making the Basadingen Trough an ideal target for DOVE. We aim to establish a chronostratigraphic and sedimentological model to identify and understand the older glaciations that affected the Basadingen Trough and the Northern Alpine foreland in general.



ICDP Project DOVE (Drilling Overdeepened Alpine Valleys): Seismic surveys across the sites

Thomas Burschil1, Hermann Buness1, Anna-Catharina Brandt2, David C. Tanner1, Gerald Gabriel1,2, Ulrike Wielandt-Schuster3, Jürgen Reitner4

1Leibniz Institute for Applied Geophysics, Germany; 2Leibniz University Hannover, Germany; 3Landesamt für Geologie, Rohstoffe und Bergbau, Freiburg, Germany; 4Geologische Bundesanstalt, Vienna, Austria

The panalpine project "DOVE" (Drilling Overdeepened Alpine Valleys), co-funded by the International Continental Scientific Drilling Program (ICDP), is drilling a series of overdeepened glacial troughs around the Alps that were formed by subglacial erosion during past glaciations. The sedimentary fill of these troughs, consisting of multiple stacked and nested glacial sequences, provides the best archives of when and where glaciers reached the Alpine forelands. The combined data from all DOVE sites comprising synchronous or asynchronous ice advances and ice extents in the different regions, will eventually provide a critical database to evaluate the various patterns in glacial-interglacial paleoclimates and landscape evolution back to the Mid-Pleistocene.

In this context, we accomplished several seismic surveys at the Tannwald Basin and Basadingen Valley as well as the Lienz Basin. Deploying small-scale vibratory sources in vertical and horizontal orientations, we examined both P- and S-wave reflection imaging. We were able to image (1) the bedrock topography and (2) the interior of overdeepened valleys in high resolution in all investigated sites. Especially, the sedimentary succession and thickness of the deposits vary in detail across the sites. Even the infills of valleys in the same catchment area differ significantly (e.g. Tannwald Basin and Basadingen Valley in the Rhine Glacier arena). Nonetheless, foreland and intra-mountainous valleys show the same overall structure for each accumulation cycle (more or less from bottom to top: basal till, basin fines, fluvial deposits). As conclusion, a detailed seismic study of each overdeepened valley is mandatory for a comprehensive understanding of overdeepened structures.



Holocene palaeoenvironmental conditions in the Baltic: Reconstructions based on palynological and biogeochemical data from IODP Expedition 347, Site M0063 (Landsort Deep)

Ulrich Kotthoff1, Thorsten Bauersachs2

1Centrum für Naturkunde, Universität Hamburg, Germany; 2Sektion Geowissenschaften, Christian-Albrechts-Universität zu Kiel, Deutschland

Restricted basins, such as the Baltic Sea, are particularly affected by global warming, which leads to intensifying stratification, severe oxygen depletion and increasing water temperatures. This, in turn, results in significant and lasting ecosystem alterations. Sediment cores recovered during IODP Expedition 347 allow reconstructing such changes. We analysed Holocene sediments from the Landsort Deep (IODP Site M0063) using combined palynological and biogeochemical approaches to reconstruct palaeoclimate variations as well as ecosystem changes and to identify anthropogenic influences. Comparison of pollen data with organic-walled dinoflagellate cysts and other palynomorphs provides a direct land-sea comparison, while increasing palynomorph concentrations are indicative for dysoxic conditions and better preservation. Our results indicate particularly warm conditions (based on TEX86) that are paralleled by high primary productivity (high TOC) and increased anoxia (low pristane/phytane ratios) around the Holocene Thermal Maximum (~7 to 5 kyr BP), Medieval Climate Optimum (~1 kyr BP) and Modern Hypoxic Period (since ~1950). For the late to middle Holocene (~7 to ~4 kyr BP), our data imply a decreasing brackish-marine influence until 4 to 3 kyr BP, accompanied by diminished aquatic primary productivity indicated by declining abundances of dinoflagellate cysts and an increase of the terrestrial vs. aquatic ratio (TARHC). Our data do not reveal equally strong terrestrial ecosystem changes until the past ca. 1000 years, which witnessed increased agricultural activity, implied by higher abundances of rye pollen as well as probably anthropogenically induced deforestation, implied by a relative decrease in non-saccate tree pollen and increase in non-arboreal pollen.



Indian subcontinent hydroclimate and vegetation changes during the last ~75 kyr reconstructed from terrestrial leaf wax stable isotope data obtained from IODP Site U1446

Stefan Lauterbach1,2, Nils Andersen1, Thomas Blanz2, Philippe Martinez3, Ralph R. Schneider1,2

1Leibniz Laboratory for Radiometric Dating and Stable Isotope Research, Kiel University, 24118 Kiel, Germany; 2Institute of Geosciences, Kiel University, 24118 Kiel, Germany; 3Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), UMR 5805 CNRS – Université de Bordeaux – EPHE – OASU, 33615 Pessac, France

Understanding past variability and forcing of the Indian Summer Monsoon (ISM) is essential for better anticipating its behaviour under future climate change scenarios and the resulting consequences for the subsistence of a large part of the world’s population. However, long-term high-resolution proxy records of terrestrial hydroclimate variability from the ISM core zone are still relatively scarce. To reconstruct ISM variability and associated vegetation changes in northern India during the last ~75 kyr, we analysed the stable hydrogen and carbon isotope composition (δD, δ13C) of long-chain n-alkanes (n-C29, n-C31) from higher terrestrial plants that are preserved in marine sediments from IODP Site U1446 in the northwestern Bay of Bengal. Being located within the reach of several large rivers, this site is characterized by high riverine input of terrestrial organic matter and thus ideal for establishing representative records of past hydroclimate and vegetation changes on the northern Indian subcontinent. The obtained δD data reveal a stepwise ISM intensification at the last glacial-interglacial transition but also several distinct centennial- to millennial-scale reductions in ISM intensity during the last glacial period. These so-called Weak Monsoon Intervals (WMIs) occurred parallel to cold events in the North Atlantic realm, e.g. during Heinrich events H1, H2, H4, H5 and H6, pointing at a close hemisphere-scale climatic teleconnection between the North Atlantic and Asia. In contrast, hydroclimate-driven changes in vegetation composition during the WMIs – reflected by the δ13C data – were only very subtle, possibly reflecting a partial resilience of the vegetation during the last glacial period.



 
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