HR: 1340h
AN: PP23A-1392    [Abstracts]
TI: African Climate Change Leads Deglaciation at Termination II
AU: * Trauth, M H
EM: trauth@geo.uni-potsdam.de
AF: Institut fuer Geowissenschaften, Universitaet Potsdam, POB 601553, Potsdam, 14415 Germany
AU: Deino, A
EM: al@bgc.org
AF: Berkeley Geochronology Center, 245 Ridge Road, Berkeley, CA 94709 United States
AU: Bergner, A G
EM: bergner@geo.uni-potsdam.de
AF: Institut fuer Geowissenschaften, Universitaet Potsdam, POB 601553, Potsdam, 14415 Germany
AU: Strecker, M R
EM: strecker@geo.uni-potsdam.de
AF: Institut fuer Geowissenschaften, Universitaet Potsdam, POB 601553, Potsdam, 14415 Germany
AB: The onshore lake-sediment sequence exposed in the Ol Njorowa Gorge south of Lake Naivasha in the Central Kenya Rift together with previously published sediment cores from the modern lake area represents a unique record of East African climate during the last two glacial-interglacial cycles. Based on sediment characteristics, diatoms, authigenic mineral assemblages and 17 single-crystal 40Ar/39Ar age determinations we found that Lake Naivasha was subjected to dramatic water level and hydrochemical changes during the last 175 kyrs. Assuming that the fluctuations recorded in the sediments reflect climate changes, the Lake Naivasha record demonstrates that between 146 and 60 kyr BP, periods of increased humidity in East Africa mainly followed maximum equatorial solar radiation in spring causing periods of more intense April-May rains every 23 kyr similar to the present. Interestingly, the most dramatic change in the Naivasha Basin occurred as early as 146 kyr BP and the highest lake level was recorded at about 139 to 133 kyr BP. This is consistent with other low-latitude climate records, but does not correspond to peaks in Northern Hemisphere summer insolation as the trigger for ice-age cycles. The Naivasha record therefore provides further evidence for a low-latitude forcing of the ice-age climate cycles. The new "Lake Naivasha Coring Project" now aims to test the hypothesis that East African climate also leads at Termination I (see abstract by Bergner et al., this session).
DE: 1655 Water cycles (1836)
DE: 1620 Climate dynamics (3309)
DE: 1645 Solid Earth
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting