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 sediments 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(3) y BP is suppressed with higher terrigenous input into the Central Indian Ocean sediment cores.