33 Glacial Geology and Proxy Records in Northeastern North America and Beyond

Monday, 21 March 2022
1:30 PM - 5:30 PM
Commonwealth Salon 1

AN ABRUPT TEMPERATURE AND HYDROCLIMATE TRANSITION IN EASTERN AFRICA DURING TERMINATION V (~430 KA)

Paper number: 33-10
Program: Theme Sessions
Time: 3:55 PM – 4:15 PM

Authors

Abstract

Over the last few million years, Africa’s climate exhibits a long-term drying trend with episodes of high climate variability coinciding with the intensification of glacial-interglacial cycles. Of particular interest is a transition between 500 and 400 ka in which fossil evidence record a major turnover of ~85% from large-body mammalian fauna to smaller-body related taxa that may have been more resilient to the changing climate (Potts et al., 2018; (Faith et al., 2012; Potts and Deino, 1995). Here, we analyze Lake Malawi drill core MAL 05–1 (~11ºS, 34ºE) to investigate if a specific climatic event stands out as a possible driver of the dramatic change observed in the East African mammal community. Core MAL 05-1 extends from the present to 1.3 Ma and is the longest high-resolution record of past climate recovered from the African continent. We used organic geochemical proxies including branched glycerol diaklyl glycerol tetraethers (GDGTs) and leaf wax carbon and deuterium isotopic records to develop temperature, vegetation, and precipitation records, respectively, between 600 and 200 ka. Results show an abrupt temperature increase of ~6°C occurring in less than 3000 years during Glacial Termination V, which is the Marine Isotope Stage (MIS) 12 to MIS 11 transition at ~430 ka. Notably, this deglacial warming coincides with enriched leaf wax deuterium isotopic values suggesting a shift to more arid conditions in interglacial MIS 11 than in glacial MIS 12. This change from a cold/wet glacial to a warm/dry interglacial contrast with the cool/dry pattern of the Last Glacial Maximum (LGM) in East Africa which transitioned to a warm/wet Holocene. We propose that the major warming and drying during Termination V in East Africa represents a significant abrupt change in the climate of eastern Africa and was a likely driver of the major faunal turnover noted in the region.

Geological Society of America Abstracts with Programs. Vol. 54, No. 3

doi: 10.1130/abs/2022NE-375274

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