TY  - JOUR
A1  - Lupien, Rachel L.
A1  - Russell, James M.
A1  - Pearson, Emma J.
A1  - Castaneda, Isla S.
A1  - Asrat, Asfawossen
A1  - Förster, Verena
A1  - Lamb, Henry F.
A1  - Roberts, Helen M.
A1  - Schäbitz, Frank
A1  - Trauth, Martin H.
A1  - Beck, Catherine C.
A1  - Feibel, Craig S.
A1  - Cohen, Andrew S.
T1  - Orbital controls on eastern African hydroclimate in the Pleistocene
JF  - Scientific reports
N2  - Understanding eastern African paleoclimate is critical for contextualizing early human evolution, adaptation, and dispersal, yet Pleistocene climate of this region and its governing mechanisms remain poorly understood due to the lack of long, orbitally-resolved, terrestrial paleoclimate records. Here we present leaf wax hydrogen isotope records of rainfall from paleolake sediment cores from key time windows that resolve long-term trends, variations, and high-latitude effects on tropical African precipitation. Eastern African rainfall was dominantly controlled by variations in low-latitude summer insolation during most of the early and middle Pleistocene, with little evidence that glacial-interglacial cycles impacted rainfall until the late Pleistocene. We observe the influence of high-latitude-driven climate processes emerging from the last interglacial (Marine Isotope Stage 5) to the present, an interval when glacial-interglacial cycles were strong and insolation forcing was weak. Our results demonstrate a variable response of eastern African rainfall to low-latitude insolation forcing and high-latitude-driven climate change, likely related to the relative strengths of these forcings through time and a threshold in monsoon sensitivity. We observe little difference in mean rainfall between the early, middle, and late Pleistocene, which suggests that orbitally-driven climate variations likely played a more significant role than gradual change in the relationship between early humans and their environment.
Y1  - 2022
U6  - https://doi.org/10.1038/s41598-022-06826-z
SN  - 2045-2322
VL  - 12
IS  - 1
PB  - Macmillan Publishers Limited
CY  - London
ER  - 
TY  - JOUR
A1  - Sier, Mark J.
A1  - Langereis, Cor G.
A1  - Dupont-Nivet, Guillaume
A1  - Feibel, Craig S.
A1  - Joordens, Josephine C. A.
A1  - van der Lubbe, Jeroen Fiji.
A1  - Beck, Catherine C.
A1  - Olago, Daniel
A1  - Cohen, Andrew
T1  - The top of the Olduvai Subchron in a high-resolution magnetostratigraphy from the West Turkana core WTK13, hominin sites and Paleolakes Drilling Project (HSPDP)
JF  - Quaternary geochronology : the international research and review journal on advances in quaternary dating techniques
N2  - One of the major challenges in understanding the evolution of our own species is identifying the role climate change has played in the evolution of hominin species. To clarify the influence of climate, we need long and continuous high-resolution paleoclimate records, preferably obtained from hominin-bearing sediments, that are well-dated by tephro- and magnetostratigraphy and other methods. This is hindered, however, by the fact that fossil-bearing outcrop sediments are often discontinuous, and subject to weathering, which may lead to oxidation and remagnetization. To obtain fresh, unweathered sediments, the Hominin Sites and Paleolakes Drilling Project (HSPDP) collected a ∼216-meter core (WTK13) in 2013 from Early Pleistocene Paleolake Lorenyang deposits in the western Turkana Basin (Kenya). Here, we present the magnetostratigraphy of the WTK13 core, providing a first age model for upcoming HSPDP paleoclimate and paleoenvrionmental studies on the core sediments. Rock magnetic analyses reveal the presence of iron sulfides carrying the remanent magnetizations. To recover polarity orientation from the near-equatorial WTK13 core drilled at 5°N, we developed and successfully applied two independent drill-core reorientation methods taking advantage of (1) the sedimentary fabric as expressed in the Anisotropy of Magnetic Susceptibility (AMS) and (2) the occurrence of a viscous component oriented in the present day field. The reoriented directions reveal a normal to reversed polarity reversal identified as the top of the Olduvai Subchron. From this excellent record, we find no evidence for the ‘Vrica Subchron’ previously reported in the area. We suggest that outcrop-based interpretations supporting the presence of the Vrica Subchron have been affected by the oxidation of iron sulfides initially present in the sediments -as evident in the core record- and by subsequent remagnetization. We discuss the implications of the observed geomagnetic record for human evolution studies.
KW  - Paleolake Lorenyang
KW  - Magnetostratigraphy
KW  - Olduvai Subchron
KW  - Vrica Subchron
KW  - Drill-core reorientation
KW  - ICDP
KW  - Paleoclimate
KW  - Hominin evolution
Y1  - 2017
U6  - https://doi.org/10.1016/j.quageo.2017.08.004
SN  - 1871-1014
SN  - 1878-0350
VL  - 42
SP  - 117
EP  - 129
PB  - Elsevier
CY  - Oxford
ER  -