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Drilling Overdeepened Alpine Valleys: First results from the Tannwald Borehole

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.


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
GeoKarlsruhe 2021