Biogenic silica in space and time in sediments of Central Indian Ocean

Abstract

Biogenic silica content in 50 surface sediments and in 7 sediment cores from Central Indian Ocean shows a variation from 1.88 to 35.76%, while radiolarian abundance (number.g/1 dried sediment) ranges from 500 to 345000. Biogenic silica accumulation rate averages 2.25 x 10/5 g.cm/2.y/1 and it is contributed from 33 to 50% of the total silica. Higher biogenic silica content of the surface sediment is well correlated with Mn, Cu and Ni concentration of the overlying manganese nodules. Higher biogenic silica (30-35%) in the surface sediments from 11 degrees to 13 degrees S, may be due to higher productivity and better preservation of siliceous tests. The lowest biogenic silica at approximately 100 to 140 x 10 sup(3) y BP is suppressed with higher terrigenous input into the Central Indian Ocean sediment cores