GEOCHEMISTRY OF SEDIMENTS ALONG THE CENTRAL EAST-COAST OF INDIA .1. MAJOR ELEMENTS

Organic carbon (OC), carbonate, Si, Al, Fe, Ti and Mn were analysed in sediment samples of 75 stations located (in 7 transects) at various d epths of coast between Bhimunipatnam-Amalapuram. The composition of al l constituents could be explained in terms of the sediment texture and the bottom topography. The concentration of Mn increased abruptly som ewhere in the deep in each transect, leaving as many as 13 marginal de ep stations to have (low) concentrations similar to the adjoining slop e (and shelf) while the remaining 27 deep stations (also) falling in a contiguous area further offshore had much higher concentrations. Mn c orrelated well with OC in this set of stations and with Fe in the set of remaining stations. The area containing the 27 Mn-rich stations cou ld be the slow depositing Bengal Fan regime while that containing the latter set of stations the fast-depositing nearshore regime, in which coastal inputs could be reaching upto 90 km and 210 km offshore north and south respectively of Tuni, a town at the centre of the coast unde r study.