GSA Annual Meeting in Seattle, Washington, USA - 2017

Paper No. 375-5
Presentation Time: 9:00 AM-6:30 PM


FOERSTER, Verena1, ASRAT, Asfawossen2, BRONK RAMSEY, Christopher3, CHAPOT, Melissa S.4, COHEN, Andrew S.5, DEAN, Jonathan R.6, DEOCAMPO, Daniel M.7, DEINO, Alan L.8, GÜNTER, Christina9, JUNGINGER, Annett10, LAMB, Henry F.11, LENG, Melanie12, ROBERTS, Helen M.13, SCHAEBITZ, Frank1 and TRAUTH, Martin H.9, (1)University of Cologne, Institute of Geography Education, Gronewaldstrasse 2, Cologne, 50931, Germany, (2)Addis Ababa University, School of Earth Sciences, Addis Ababa, 1176, Ethiopia, (3)Oxford Radiocarbon Accelerator Unit, University of Oxford, Oxford, OX1 3QY, United Kingdom, (4)Aberystwyth University, Department of Geography and Earth Sciences, Aberystwyth, United Kingdom, (5)Department of Geosciences, University of Arizona, Tucson, AZ 85721, (6)University of Hull, School of Environmental Sciences, Hull, United Kingdom, (7)Geosciences, Georgia State University, 24 Peachtree Center Avenue Northeast, Atlanta, GA 30303, (8)Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, CA 94709, (9)University of Potsdam, Institute of Earth and Environmental Science, Potsdam, Germany, (10)Eberhard Karls Universität Tübingen, Department of Earth Sciences, Tuebingen, Germany, (11)Institute of Geography and Earth Sciences, Aberystwyth University, Aberystwyth, SY23 3DB, United Kingdom, (12)NERC Isotope Geosciences Laboratory, British Geological Survey, Keyworth, Nottingham, NG12 5GG, United Kingdom, (13)Department of Geography and Earth Sciences, Aberystwyth University, Llandinam Building, Penglais Campus, Aberystwyth, SY23 3DB, United Kingdom,

Through Continental Scientific Drilling, six sites in Ethiopia and Kenya, all adjacent to key paleoanthropological sites have been investigated as part of the Hominin Sites and Paleolakes Drilling Project (HSPDP), aiming at an enhanced understanding of climatic influences on human physical and cultural evolution. Together the sites cover the last ~3.5 Ma of climate change. Initial results show that sediment core records archive environmental change during diverse milestones in human evolution, and times of dispersal and technological and cultural innovation. The 280 m-long Chew Bahir lacustrine record, recovered from a tectonically-bound basin in the southern Ethiopian rift in late 2014, covers the past ~550 ka of environmental history, a time period that includes the transition to the Middle Stone Age, and the origin and dispersal of modern Homo sapiens.

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.