Climatology of the Eastern Arabian Sea during the last glacial cycle reconstructed from paired measurement of foraminiferal delta sup(18)O and Mg/Ca

Abstract

Paired measurements of Mg/Ca and delta sup(18)O of Globigerenoides sacculifer from an Eastern Arabian Sea (EAS) sediment core indicate that sea-surface temperature (SST) varied within 2 degrees C and sea-surface salinity within 2 psu during the last 100 ka. SST was coldest (approx. 27 degrees C) during Marine Isotope Stage (MIS) 4 and 2. Sea-surface salinity was highest (approx. 37.5 psu) during most of the last glacial period (approx. 60-18 ka), concurrent with increased delta sup(18)O sub(G. sacculifer) and C/N ratios of organic matter and indicative of sustained intense winter monsoons. SST time series are influenced by both Greenland and Antarctic climates. However, the seasurface salinity time series and the deglacial warming in the SST record (beginning at approx. 18 ka) compare well with the LR04 benthic delta sup(18)O-stack and Antarctic temperatures. This suggests a teleconnection between the climate in the Southern Hemisphere and the EAS. Therefore, the last 100-ka variability in EAS climatology appears to have evolved in response to a combination of global climatic forcings and regional monsoons. The most intense summer monsoons within the Holocene occurred at approx. 8 ka and are marked by SST cooling of approx. 1 degrees C, sea-surface salinity decrease of 0.5 psu, and delta sup(18)O sub(G. sacculifer) decrease of 0.2 ppt.