Recent paleoclimatic work on terrestrial and marine deposits from Asia and the Indian Ocean has indicated abrupt changes in the strength of the Asian monsoon during the last deglaciation. Comparison of marine paleoclimate records that track salinity changes from Asian rivers can help evaluate the coherence of the Indian Ocean monsoon (IOM) with the larger Asian monsoon. Here we present paired Mg/Ca and ??18O data on the planktic foraminifer Globigerinoides ruber (white) from Andaman Sea core RC12-344 that provide records of sea-surface temperature (SST) and ??18O of seawater (??18Osw) over the past 25,000 years (ka) before present (BP). Age control is based on nine accelerator mass spectrometry (AMS) dates on mixed planktic foraminifera. Mg/Ca-SST data indicate that SST was ???3 ??C cooler during the last glacial maximum (LGM) than the late Holocene. Andaman Sea ??18Osw exhibited higher than present values during the Lateglacial interval ca 19-15 ka BP and briefly during the Younger Dryas ca 12 ka BP. Lower than present ??18Osw values during the B??lling/Aller??d ca 14.5-12.6 ka BP and during the early Holocene ca 10.8-5.5 ka BP are interpreted to indicate lower salinity, reflect some combination of decreased evaporation-precipitation (E-P) over the Andaman Sea and increased Irrawaddy River outflow. Our results are consistent with the suggestion that IOM intensity was stronger than present during the B??lling/Aller??d and early Holocene, and weaker during the late glaciation, Younger Dryas, and the late Holocene. These findings support the hypothesis that rapid climate change during the last deglaciation and Holocene included substantial hydrologic changes in the IOM system that were coherent with the larger Asian monsoon. ?? 2007 Elsevier Ltd. All rights reserved.
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A ???25 ka Indian Ocean monsoon variability record from the Andaman Sea