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Tracking the pace of Middle Pleistocene Revolution in the southern Alpine Foreland

Author Soumita PATRA
Director of thesis Naki Akçar Institute of Geological Sciences, University of Bern, Baltzerstrasse 1-3, 3012, Bern, Switzerland
Co-director of thesis Susan Ivy-Ochs Labortory of Ion Beam Physics (LIP),ETH Zurich, Schafmattstrasse 20, 8093, Zurich, Switzerland
Summary of thesis The southern Alpine foreland, enclosed between the Adriatic Sea and the Alps, represents a key area to understand the climate and environmental transition between Mediterranean and Central Europe through the Quaternary global climate change. During the Middle Pleistocene Revolution (MPR), the structure of the glacial-interglacial cycles changed from 41 ka (low-amplitude/high-frequency) to 100 ka (high-amplitude/low-frequency) oscillations. This transition resulted in changes in landscape evolution. These changes are recorded terrestrial geo-archives, which are generally discontinuous in space and time. In the Middle Pleistocene the first major expansion of the alpine glaciers triggered a change in drainage patterns and a marked increase in erosion rates in the southern Alpine Foreland, where the MPR is commonly attributed to re-organization of the drainage system of the rivers. During the Middle Pleistocene glaciers advanced repeatedly from the Alps to the Alpine foreland. The chronology of the records of those changes in the southern Alpine Foreland is not completely constrained. Therefore, the aim of this study is to quantify landscape evolution since the onset of Early Pleistocene based on the detailed study of glacio-fluvial deposits which was accumulated by glacial meltwater. For this, we will apply detailed mapping, analyze the sedimentology of these sequences and calibrate their chronology with cosmogenic nuclides. We will apply both depth-profile and isochron-burial techniques with cosmogenic 10Be, 26Al and 36Cl to date these deposits. Based on the reconstructed chronology, we will report post-depositional incision rates into bedrock. For the provenance analysis, the lithology of approximately 250 clasts from the gravel fraction (16-63 mm) will be determined and counted. Subsequently, counted gravels will be grouped into different lithological classes. In addition key lithologies will be identified. Based on the results, we will define the provenance of sediments, gather information on their transport, depositional environments, date their accumulation and calculate bedrock incision rates.
Administrative delay for the defence