GRANULOMETRIC STUDIES, RATE OF SEDIMENTATION AND OSTRACOD DISTRIBUTION FROM A SHORT CORE OFF ONGOLE COAST, ANDHRA PRADESH, BAY OF BENGAL

A preliminary study on the marine Ostracoda is carried out from a shallow short core of length 20 cm collected from the region of Bay of Bengal, off the coast of Ongole using a multicorer during the ORV Sagar Kanya cruise (SK-308 Leg 1), at a water depth of 47 metres. The core is further sampled at an interval of 1 cm and thus, a total of 20 samples were obtained and are subjected to standard micropaleontological and sedimentological analyses. The classification by Hartmann and Puri (1974) is followed through which 41 ostracod taxa belonging to 33 genera of the order Podocopida have been identified, from which 2 species belong to suborder Platycopa and the remaining to suborder Podocopa. Ostracod assemblage recorded is characteristic of shallow insitu marine, inner shelf and tropical in nature. Sedimentological parameters such as CaCO3 Organic matter and sand-silt-clay ratios were estimated and their down core distribution is discussed. Granulometric studies reveal that fine grained silt and clay are more than sand in the core sample reflecting on low energy condition of sediment deposition. Ostracods from the area are larger in size, ornamented and well preserved. Approximate averages of only 42 specimens are found per 10 grams. The ratio between the carapaces and open valves has been taken into consideration for determining the relative rate of sedimentation and it has been identified as slower rate of sedimentation prevailing in the area.