1,2,2,4,5,6,1,8,2,4,1,2,9,10,4,3,11,12,13,14,1,2,4,8,- 1Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Marine Geology, Bremerhaven, Germany (johann.klages@awi.de)
- 2Cluster of Excellence „The Ocean Floor – Earth’s Uncharted Interface”, University of Bremen, Germany
- 3British Antarctic Survey, Cambridge, UK
- 4MARUM – Center for Marine Environmental Sciences, Germany
- 5Chair of Organic Biogeochemistry in Geo-Systems, RWTH Aachen University, Germany
- 6Department of Geography and Environmental Sciences, Northumbria University, UK
- 7Institute of Earth Sciences, University of Heidelberg, Germany
- 8Faculty of Geosciences, University of Bremen, Germany
- 9Environmental Physics, University of Bremen, Germany
- 10Institute for Earth System Science and Remote Sensing, University of Leipzig, Germany
- 11Australian Centre for Excellence in Antarctic Science, Institute for Marine and Antarctic Studies, University of Tasmania, Australia
- 12Department of Earth Science and Engineering, Imperial College London, UK
- 13Division of Water and Environmental Engineering, KTH Royal Institute of Technology, Sweden
- 14GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel, Germany
- *A full list of authors appears at the end of the abstract
West Antarctica’s transition to its first extensive glaciation likely post-dated the establishment of the East Antarctic Ice Sheet (EAIS) by more than 10 million years, yet the timing and nature of West Antarctic Ice Sheet (WAIS) development have remained poorly constrained due to the absence of reliable sediment records. Newly recovered sediment sequences drilled with the seafloor drill rig MARUM-MeBo70 during RV Polarstern Expedition PS104 from the eastern Amundsen Sea Embayment were explored using multi-proxy sediment analyses alongside biostratigraphic and isotopic dating methods. These revealed ice-proximal terrigenous and diatomaceous diamictites as well as diatomaceous mudstones indicating the advance of a substantial WAIS to these drill sites already prior to the Oligocene–Miocene transition (~23 million years ago). Coupled climate-ice sheet modelling simulates the growth of a distinct WAIS separated from the EAIS, which expanded far into basins below sea level. Therefore, our new sedimentary data validate these model results and demonstrate that extensive WAIS expansion to the coast occurred several million years earlier than previously thought.
K. Gohl, G. Kuhn, V. Afanasyeva, J. E. Arndt, B. Ebermann, C. Gebhardt, K. Hochmuth, K. Küssner, Y. Najman, F. Riefstahl & M. Scheinert
How to cite: Klages, J. P., Hillenbrand, C.-D., Bickert, T., Bauersachs, T., Salzmann, U., Titschack, J., Bohaty, S. M., Müller, J., Frederichs, T., Knahl, H. S., Lohmann, G., Ehrmann, W., Freudenthal, T., Larter, R. D., Hochmuth, K., van de Flierdt, T., Reinardy, B. T. I., Eisenhauer, A., Knorr, G., and Pälike, H. and the Science Party of Expedition PS104: Marine-terminating West Antarctic Ice Sheet during the latest Oligocene, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1740, https://doi.org/10.5194/egusphere-egu26-1740, 2026.
