Implications of organic carbon, trace elemental and CaCO_3 variations in a sediment core from the Arabian Sea

摘要

Arabian Sea differs from other oceanic areas by strong seasonal variations in sea surface circulation controlled by the monsoonal wind system, very high primary productivity (PP) and the presence of an intense Oxygen Minimum Zone (OMZ). Sediment core, collected from a depth of 803 M in OMZ of eastern Arabian Sea, was analyzed for organic carbon, CaCO_3, grain size and trace metals (Cu, Zn, Cr, Mn and Fe). Organic carbon and CaCO_3 varied from 0.5-4.7% and 34-55.9% respectively and exhibit an inverse relation, whereas a positive correlation is observed between organic carbon and clay fraction in the upper 150 cm. Cu, Zn and Cr show positive correlation with organic carbon and is negatively related to CaCO_3. Mn and Cr show inverse correlation due to the influence of redox conditions of the sedimentary column. Low productivity, oxic conditions and less intense southwest monsoon prevailed during the deglacial period. Productivity has increased from 16 kyr to the modern age.