A 131-Year High-Resolution Record of Coccolith Assemblages in Laminated Sediments from the Arabian Sea

Abstract

This study looked at a 131-year high-resolution record of coccolith assemblages in laminated sediments from the Arabian Sea. The SO90-39KG core obtained from the northeastern Arabian Sea was sampled at an annual resolution for the period of 1861-1993 A.D. Analyses of Scanning Electron Microscope (SEM) images of these samples revealed a declining trend in the relative abundances of the upper to mid photic zones coccolithophore species and an increasing trend in the relative abundances of the lower photic zone coccolithophore species over the 20th century. These trends could be the result of a reduction in paleoproductivity caused by the deepening of the nutricline and the thermocline due to a warming climate. The 1883 A.D. Krakatau eruption was also evident in the results as decreased paleoproductivity. Similarities between the observed trends and monsoon precipitation as well as sunspot cycle records were also observed. No particular similarity with El-Nino Southern Oscillation (ENSO) record could be detected. Caution should be observed regarding the correlation of the results obtained here to past climatic and geologic events.