Response of cassidulinids to the oxygen minimum zone intensity fluctuations during the last 70 KYR in the Eastern Arabian sea, Off Goa

Abstract

In order to study the response of benthic foraminifera, a closely spaced samples of a 9.65m long sediment core which was retrieved from 1230m water depth off Goa, were analysed both qualitatively and quantitatively. The down-core abundance pattern of cassidulinids shows millennial-scale variation almost paralleling the organic-carbon-concentration (%Corg) sediment record. The cassidulinid population appears to be controlled by both bottom oxygen condition and primary productivity. This study deciphers that the intervals during 15 – 17 kyr BP, 23 – 24 kyr BP, 28 – 29.5 kyr BP, 38 – 39 kyr BP, 45 – 46 kyr BP and 60 – 61 kyr BP were the periods of cassidulinid minima related to the weak Oxygen Minimum Zone (OMZ) intensity and low surface primary productivity in the eastern Arabian Sea. These events of abundance minima of cassidulinds correspond with the time equivalents of north Atlantic Heinrich Events.