Neogene Paleoenvironmental changes in the McMurdo Sound region: High resolution chemical and sedimentological analysis of Miocene (~17 Ma) to Pleistocene sediments from ANDRILL Site SMS

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In late 2007, a 1138 m thick sediment core was drilled from a sea-ice platform at ANDRILL (ANtarctic geological DRILLing) site SMS (Southern McMurdo Sound, Ross Sea, Antarctica). The core covers Early Miocene (~20 Ma) to Pleistocene strata deposited on the western flank of the Victoria Land Basin (VLB), a structural half-graben that forms part of the West Antarctic Rift system. On this core we propose to combine high-resolution on-ice measurement of chemical element concentrations using XRF core-scanner with off-ice highprecision chemical and sedimentological analysis on bulk samples (XRF, XRD, ICP-MS, biogenic components) and individual lithoclasts (LA-ICP-MS, electron microprobe, microscopy). The resulting multiple dataset will provide detailed information on sediment composition and, thus, contribute to several scientific objectives of ANDRILL such as (i) the history of the Ross ice shelf (RIS) expansion and retreat since ~20 m.y., the (ii) varying control of the West (WAIS) and East Antarctic ice sheets (EASI) on RIS dynamics, (iii) seaice presence/absence in the McMurdo region, and the history of Neogene sediment provenance and accumulation rates in the VLB. Our major goal is to improve the understanding of the Miocene paleoenvironmental evolution of Antarctica with special emphasis on high-resolution analysis of the Mid-Miocene climatic optimum (~18-15 Ma), and the subsequent onset of major cooling along with the key question on the stability of coldpolar climate conditions during the last 14 m.y.