Project Details
Projekt
How wet is wet? Reconstruction of water availability in the cradle of humanity
Applicants
Dr. Annett Junginger; Dr. Hubert Vonhof
Subject Area
Mineralogy, Petrology and Geochemistry
Geology
Geology
Term
since 2022
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 497337382
The role that climate and environmental history may have played in influencing human evolution is controversially discussed among paleoanthropologists for decades. Inspired by these discussions, the Hominin Sites Paleolakes Drilling Project (HSPDP) conducted five deep drilling campaigns adjacent to key hominin fossil sites in Eastern Africa. The Chew Bahir Basin in Southern Ethiopia is one of these sites and near to the oldest find site of Homo sapiens in Eastern Africa and neighboring basin of Lake Turkana rich in even older hominin fossils. Analysis of the ICDP-Chew Bahir drill cores CHB14 revealed, that over the past 620 ka, phases of environmental stability and instability occur contemporaneously with milestones in human history including pulsed dispersal events out of Africa coinciding with potential humid periods (pluvials). Although proxies in Chew Bahir sediment analysis have intensely been tested for their reliability we still lack quantitative information on temporal water availability and an understanding of the driving and competing mechanisms. The overall aim of the project is therefore to provide a 620-ka record of hydrological changes in the S-Ethiopian Rift by applying a multi-isotope study (87Sr/86Sr, δ18O, δ13C) on microfossils extracted from the CHB14 cores. 87Sr/86Sr will be used to reconstruct connectivity (today not the case) of S-Ethiopian lakes Abaya, Chamo and Chew Bahir. Connected lake basins reflect +25-40% enhanced precipitation and present several connected large freshwater bodies on the migration route out of Africa. δ18O and δ13C will provide additional information on the evaporative as well as open/closed status of the fluctuating Chew Bahir paleo-lake. Furthermore, a paleo-seasonality study will apply δ18O and δ13C to seasonal increments of fossil stromatolites and freshwater oyster shells from the last African Humid Period (15-5 ka). The study will provide detailed insights into E/P balance of the paleo-lake and possible facies shifts even during one precessional-forced pluvial. The outcome of this project will provide the longest (nearly) continuous record of water availability in the Ethiopian Rift and shed light on the impact and interference of orbital parameters and glacial-interglacial cycles as well as short-term influences on the region's water budget. The results will help refining hypotheses on hominin dispersals which suggest that wetter environmental conditions may have facilitated long-range human expansion into new territories, while less favorable dry periods may have led to spatial constriction and isolation of local human populations.
DFG Programme
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