HR: 11:00h
AN: PP22A-03    [Abstracts]
TI: Basin-wide Millennial Cycles in Arabian Sea Climate Over the Last Glacial
AU: * Pourmand, A
EM: apourman@tulane.edu
AF: Tulane University, Room 120, Dinwiddie Hall, Department of Earth and Environmental Sciences, 6823 St. Charles Avenue, New Orleans, LA 70118
AU: Marcantonio, F
EM: fmarcan@tulane.edu
AF: Tulane University, Room 120, Dinwiddie Hall, Department of Earth and Environmental Sciences, 6823 St. Charles Avenue, New Orleans, LA 70118
AB: High-frequency Dansgaard-Oeschger (D-O) and Heinrich cycles first discovered in the records of North Atlantic ice and marine sediments have been found to extend beyond the North Atlantic There is ample evidence for these millennial cycles of climate variability in the sediments of the Arabian Sea. We employ uranium-series radionuclide proxies to determine changes in the fluxes of sedimentary components in two cores from the western (W) and northeastern (NE) Arabian Sea in order to investigate fluctuations of export production and wind strength on a large regional scale during the last glacial period. In the NE Arabian Sea off of the Pakistani margin, ²³⁰Th-derived detrital (eolian) fluxes are highest during periods consistent with the timing of North Atlantic D-O stadial and H 1-7 events. Authigenic uranium concentrations, which we interpret as a proxy for primary productivity, also show an increase during North Atlantic D-O interstadials. Preliminary results from W Arabian Sea sediments off of the Oman margin corroborate that these millennial cycles in productivity and eolian fluxes are indeed basin-wide events. Authigenic U concentrations in these sediments are, on average, about twice those measured in the NE Arabian Sea, suggesting, qualitatively, an enhancement of primary productivity in the western part of the basin. In contrast, fluxes of eolian material to the Oman margin are, on average, more than 10 times lower than those delivered to the Pakistani margin, even though the patterns of millennial variability are virtually identical. We associate enhanced export production and a decreased eolian input during relatively warmer D-O interstadials with an intensification of southwest monsoonal winds. Similarly, decreased export production is coincident with an increase in eolian fluxes during North Atlantic stadial and H events. These results provide strong evidence for a basin-wide atmospheric teleconnection between Arabian Sea and North Atlantic climate on sub-Milankovitch timescales.
DE: 1050 Marine geochemistry (4835, 4850)
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 3344 Paleoclimatology
DE: 4267 Paleoceanography
DE: 4279 Upwelling and convergences
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2005 Joint Assembly