THE CHEW BAHIR DRILLING PROJECT (HSPDP). FROM MUD, GRAINS AND CRYSTALS TO >500,000 YEARS OF CONTINUOUS CLIMATE HISTORY IN SOUTHERN ETHIOPIA
To develop a continuous climate history based on sediment core composition is challenging due to the complex relationship between climate and sedimentary deposits. Our composite core record represents >90% recovery, verified through multi-proxy inter-core correlation, together with high-resolution µXRF, XRD, and sedimentological data. Initial results suggest mineralogical and geochemical proxies are potential climate indicators of wet, dry and hyper-arid climate intervals. Mineral assemblages include salinity indicators such as zeolitic alteration and authigenic clay minerals. Understanding mineral alteration in the Chew Bahir records will enable interpretation of µXRF-derived proxies (e.g. K indicating aridity), and provide direct paleohydrologic data. The high quality geochronology, nearly continuous record, and our growing understanding of site-specific proxy formation will provide a robust environmental history on decadal to orbital timescales. This will enable us to test current hypotheses of the impact of climate change and variability on human evolution and dispersal.