LATE MIOCENE TO PLEISTOCENE LITHOSTRATIGRAPHIC CHANGES FROM IODP SITE U1522 ON THE ROSS SEA CONTINENTAL SHELF

International Ocean Discovery Program (IODP) Expedition 374 recovered 702 meters of Late Miocene to Pleistocene sedimentary sequences from the outer continental shelf in the Ross Sea at Site U1522. Geochemical and mineralogical comparisons of bulk sediment between the Antarctic Geological Drilling Project (ANDRILL) AND-1B site and U1522 will allow us to assess whether ice streams from WAIS vs. EAIS contributed to ice sheet advances across the shelf during Neogene and Quaternary lowstand events.

IODP Site U1522 primarily consists of stacked diamictites. Here we present a new bulk mineralogy record derived from X-ray diffraction (XRD) to examine compositional changes in quartz, feldspar, albite, muscovite, biotite, calcite, and kaolinite. We integrate this new mineralogy record with physical property data (e.g., MS, NGR, color), clast count data, CT-scan imagery, bulk sediment d13C of organic matter, and X-ray fluorescence (XRF) core scanning data that has been calibrated to major and trace elements in order to provide a high-resolution record of sedimentary geochemical variations, and sedimentary facies analysis to evaluate late Miocene to Pleistocene changes in relative ice sheet proximity, sediment provenance, and paleoproductivity. We also use downhole logging data to assess lithological changes across core gaps, including an unrecovered interval between 230 and 250 mbsf that likely corresponds to the mid-Pliocene Warm Period. This integrated approach allows us to develop a better understanding of Antarctic ice sheet sensitivity in a warming world.