Accumulation of Organic Carbon in Northwestern Arabian Sea Sediments

Abstract

In this study accumulation of organic carbon in marine sediments of northwestern Arabian sea has been discussed. This paper presents the geochemical analysis of Organic carbon content and accumulation, 013 stable carbon isotope and Ba/AI. The primary objective was to investigate the high resolution information about the variations in paleoproductivity and source of organic matter in sediments below an upwelling area. Undisturbed sediments (Piston core NIOP-486) of late Pleistocene time were collected during Netherlands Indian Ocean Program (NIOP-1992- 93). The core NIOP-486 was raised from a depth of 2077 meters near the Owen Ridge. This core records deposition history of last 200,000 years and includes 4 warm and 3 cold periods. The distribution of organic carbon content in studied core shows a pronounced cyclicity during glacial and interglacial stages. Organic carbon accumulation trends show that high sedimentation rates in glacial stages results in rapid burial and hence increase organic carbon accumulation. Paleoproductivity indicator Ba/AI has been used to compare with the organic carbon content and is correlated with the warm and cold periods variations in monsoons upwelling intensity. Generally, low paleoproductivity is found in glacial stages. The organic carbon content and accumulation, in sediments however seems to differ from the paleoproductivity trends shown by Ba/AI in glacial sediments of stage 6. 013 C.org isotope results of the core NIOP-486 confirm that organic matter in sediments is predominantly marine (-20 to _23%°).