HR: 1340h
AN: PP13A-0592    [Abstracts]
TI: High-Resolution Holocene SST Changes in the Northeastern Arabian Sea Reveal a Complex Monsoon History
AU: * Lueckge, A
EM: a.lueckge@bgr.de
AF: Federal Institute for Geosciences and Natural Resources, Stilleweg 2, Hannover, 30655 Germany
AU: Staubwasser, M
EM: m.staubwasser@mineralogie.uni-hannover.de
AF: University Hannover, Institute of Mineralogy, Callinstrasse 3, Hannover, 30167 Germany
AU: Scheeder, G
EM: scheeder@bgr.de
AF: Federal Institute for Geosciences and Natural Resources, Stilleweg 2, Hannover, 30655 Germany
AB: Sediments off Pakistan provide biological and sedimentological evidence of past changes in the Indian monsoon system. We measured planktonic foraminiferal oxygen isotopes and alkenones in a complete laminated Holocene sequence from the Arabian Sea oxygen minimum zone. Our age model is based on varve stratigraphy and 44 AMS-$^{14}$C ages. Significant SST changes of up to $\sim$ $3\deg$C suggest a more complex monsoon history during the Holocene than previously thought. A gradual, long-term warming trend occurs between 9 and 6 ka BP reaching a thermal maximum of about $27\deg$C at $\sim$ 6 ka BP. After 6 ka BP temperatures decrease to $25.5\deg$C with superimposed centennial variations. The unusual SST trend is difficult to explain with the classical model of a mid-Holocene summer monsoon wind maximum as reported in the western Arabian Sea, which would cool the surface ocean. A warmer and more humid winter monsoon possibly caused by mid-Holocene Himalayan glaciation may have contributed to the warming in the Arabian Sea. A prominent $\delta$$^{18}$O change at 4.2 ka BP further amplified by the SST record is coherent with the greatest historically recorded drought in western Asia and tropical Africa.
DE: 9340 Indian Ocean
DE: 4267 Paleoceanography
DE: 1055 Organic geochemistry
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting