Summary of Abstract Submission

Abstract Submission No. IO50-05-0021PresentationPoster


J.N.Pattan*1, Thomas J Algeo 2, Parthiban, G.1, A. Amonkar1

1 CSIR-Natioonal Institute of Oceanography, Doan Paula, Goa, 403 04, India
2 Department of Geology, University of Cincinnati, Cincinnati, Ohio 45221-0013, USA


Productivity proxies (total organic carbon, calcium carbonate, and phosphorous) and redox-sensitive elements (uranium, molybdenum, and cadmium) were analysed for the last ~18 ka in a sediment core located off Cochin (southern India) in the southeastern Arabian Sea at a water depth of 280m, in order to investigate the linkage between productivity and redox conditions in a mainly suboxic open-ocean system. These proxies document a combination of higher productivity and more reducing conditions during the last deglaciation (~18 to 14 ka) and late Holocene (4 ka to present) versus lower productivity and less reducing conditions between these intervals (~14 to 4 ka). The productivity and redox proxies all show strong positive correlations from ~18 to 4 ka, suggesting that variations in productivity controlled redox conditions in the deep watermass during this interval. This relationship is supported by patterns during the last deglaciation, when a decrease in productivity at~16 ka preceded improved deep water oxygenation by ~14 ka. Titanium (Ti), a terrigenous element, increased at ~14 to 4 ka, suggesting intensification of the southwest monsoon and a consequent increase in freshwater runoff and terrigenous sediment fluxes at that time. It is evident that calcium carbonate flux control the bulk accumulation and in turn control the redox conditions in the sediment core.