GLACIAL TO INTERGLACIAL CONTRASTS IN THE CALCIUM-CARBONATE CONTENT AND INFLUENCE OF INDUS DISCHARGE IN 2 EASTERN ARABIAN SEA CORES

Two cores collected in the eastern Arabian Sea were studied for coarse fraction, calcium carbonate content and Globorotalia menardii complex abundance. Based on the fluctuations of calcium carbonate and G. menardii complex abundance, the Holocene/Pleistocene boundary is placed at 50 cm level from the top of the core and the Last Glacial Maximum (LGM) at 80 cm depth for the northern Arabian Sea core. While for the southern Arabian Sea core the boundaries of Holocene/Pleistocene and LGM are placed at 40 cm and 65 cm respectively. The carbonate content and G. menardii complex abundance variations in these cores reveal that carbonate maxima with less abundance of G. menardii complex reflects glacials (cold periods). While carbonate minima with high abundance of G. menardii complex reflects interglacials (warm periods). High percentage of coarse fraction and CaCO3 during glacials attributed to high productivity, low percentage of coarse fraction and CaCO3 is due to less productivity during interglacials. Productivity variations during glacial and interglacial periods in the Arabian Sea is discussed in relation to SW and NE monsoon intensities. Northern Arabian Sea core shows less CaCO3 during Holocene period and high during glacial periods suggesting that the dilution by terrigenous flux derived from the Indus river is significantly lower during glacial periods than in the Holocene period.