Summary of Abstract Submission

Abstract Submission No. IO50-02-0009PresentationPoster

U-TH SERIES NUCLIDES IN THE INDIAN OCEAN: INFERENCES ON PARTICLE TRANSPORT AND SEDIMENTARY RECORD

M.M. Sarin*1

1 Physical Research Laboratory, Ahmedabad-380009, INDIA

ABSTRACT :

The Bay of Bengal, an embayment of the Indian Ocean occupying ~2.2x106 km2, is a unique ocean basin that receives large quantities of fresh water and sediment supply (~109tons/yr) from several rivers draining the Indian sub-continent. A first comprehensive study on the geochemistry and geochronology (based on depth profiles of U-Th series nuclides) of sediments from the Bay of Bengal and the equatorial Indian Ocean was carried out in the late seventies (Sarin et al. 1979). An unambiguous signal of Th-230 excess (230Thex) was measurable in sediments cores south of 13oN; whereas in the north, 230Thex signal was not detectable suggesting rapid sediment accumulation to the north of 13oN. The mean clay accumulation rates in the latitudinal belt 13oN to 02oS\ ranged between 1 to 7 mm/ky. The scatter and changes in the slope of 230Thex profiles further suggest that sediment history of this region has gone through episodic changes in the past. A later study (Sarin et al. 2000) on 230Th, 228Th and 210Pb in suspended particles settling through the water column has provided insight into the processes and their removal by vertical flux and/or lateral transport (removal at the ocean boundaries). The fluxes of 210Pb and 230Th are in excess compared to the overhead production suggesting re-suspension of sedimentary material and/or lateral transport in the Central Bay.