UTTAR PRADESH JOURNAL OF ZOOLOGY

This study examines the biogenic silica (BSi) content in a sediment core from the southeastern Arabian Sea (SEAS) to reconstruct paleoceanographic changes over the past 14 kyr. The study investigates the grain size distribution and biogenic silica content of marine sediments. There is a significant amount of silt in the sediments in the entire core, which varies between 80% and 96%. BSi content ranged from 3.4% to 4.4%, with notable fluctuations during key climatic events. Elevated BSi during the Bølling-Allerød event (13.5-13 kyr BP) suggests enhanced productivity linked to intensified Indian Summer Monsoon (ISM) and upwelling. Conversely, the Younger Dryas (12.9-11.6 kyr BP) exhibited reduced productivity, interrupted by multi-centennial scale fluctuations. The early Holocene (11.7-8.5 kyr BP) was characterized by low BSi, indicative of reduced upwelling due to increased monsoonal precipitation and freshwater influx. The Holocene Climatic Optimum (8.5-4.5 kyr BP) saw a resurgence in productivity, correlating with heightened ISM activity and an intensified oxygen minimum zone (OMZ). By the late Holocene (~6-1.1 kyr BP), BSi content stabilized, reflecting steady paleoproductivity under a weakened monsoon regime. These findings underscore the intricate link between monsoon dynamics, upwelling, and productivity in the SEAS during the late Quaternary. Changes in marine paleoproductivity could reflect the history of the marine biogenic cycle process.