Geochemistry of core sediments from Gulf of Mannar, India

Abstract

The Gulf of Mannar, located between India and Sri Lanka, is a shallow embayment of the Bay of Bengal. The gulf, which has been declared a bio-reserve is a highly productive area endowed with rich marine fauna including corals. In order to study the origin and nature of the sediments and paleo-environment, 2.6 m length core was collected with 5cm interval at 1320m water depths. Textural studies indicate that the sediments have been poorly sorted and most of the sub samples are silty clay and few top samples are sandy silty clay. The nature of organic matter also indicate high sedimentation rate. Based on the behaviors of CaCO3, Organic matter (OM) and textural parameters the core was studied under the three units. The first unit represents surface to 65cm (unit-1), the second unit (unit-2) represents 65cm to 165cm and third unit represents 165 cm to the bottom of the core. The major oxide geochemistry shows higher concentration of detritus constituents. The trace element studies indicate ferruginous nature for all elements except Cu and Zn. The element/Al ratios also are computed. The geochemical analysis for trace elements like Mn, Cr, Cu, Ni, Co, Pb, and Zn has been carried out for core sediments. Normalization with Al values for all the trace elements have been calculated.