Oxygen isotope records of Globigerina bulloides across a north-south transect in the south-western Indian Ocean

Abstract

Oxygen isotopic analysis of planktic foraminifera (Globigerina bulloides) from a total of 23 surface sediment samples collected along a north-south transect (9.69°N to 55.01°S) in the southwestern Indian Ocean during the Indian Pilot Expedition to Southern Ocean (PESO), was carried out to assess the relationship between oxygen isotopic composition and ambient seawater temperature and salinity. An increasing trend in the δ 18 O value is noticed towards higher latitude.Apparently such an increase in δ 18 O values is inversely related to the seawater temperature changes along the transect. However, slight mismatch is observed at a few stations, which is attributed to significant seawater salinity changes. The preliminary results of the present study, if extended to the subsurface sediments coupled with other parameters, may contribute to the reconstruction of the paleohydrography of the region, especially the position of various seawater fronts during the geologic past, albeit with areal limitation.