Paleothermometric fluctuations and ornamentation pattern of Ostracoda species from a short core, off Ongole, Bay of Bengal, South-east Indian coast

Abstract

An investigation on the elemental chemistry and its fluctuation in Ostracoda carapace to render the environmental traits from off Ongole, Andhra Pradesh is outlined in the paper. Paleothermometric elucidation of the environment using elements Ca, Mg, As, Nb, Sb, Al, Si, Cl, K and Na and the ornamentation pattern exhibited by Ostracoda are identified and ventilated. A short core of length 20 cm was collected from the study area using a multicorer during the ORV Sagar Kanya cruise (SK-308 Leg 1) fieldwork, at a water depth of 47 m. Ostracoda separated from the sediment matrix were subjected to standard micro-paleontological procedures. The elemental weight percentages reveal that the distribution of the elements in the carapace for different species is not the same and fluctuates along the downcore. The occurrence of Niobium in the offshore sediments is observed to be of terrestrial influence, which is derived from granitic and pegmatite rocks of the adjoining coastal terrain. A traceable quantity of Antimony and Arsenic is identified in the carapace of the certain Ostracoda. Mg/Ca ratio in carapace indicates that an endurance of mild temperature fluctuation to the downcore. Smooth, spinose, pitted, punctate and reticulate ornamentation are found occurring in Ostracoda carapace which reflects on the depositional environment and granulometry.