Evidences of climatic variations during Late Pleistocene- Holocene in the eastern Bay of Bengal

Abstract

Based upon the variations of clay minerals, sediment texture, heavy mineral assemblage and sup(230)Th excess in the Late Pleistocene sediments of a hemipelagic core from the eastern Bay of Bengal (2713 m water depth), 35 cm and 73-78 cm levels are assigned as Holocene-Pleistocene boundary and last glacial maxima (LGM) respectively. Two dominant arid phases and weak monsoon around LGM (73-110 cm) and at Holocene-Pleistocene boundary are identified from high concentration of chlorite, C/I ratio maxima (aridity reflector), decrease in characteristic clay mineral suites of humid climate, i.e. smectite and illite and a Iow K/C ratio. The intensity of monsoon between LGM and 15 ky sup(-1) has been cyclic, and enhanced thereafter until the beginning of Holocene as deduced from high smectite, reduced chlorite and higher K/C ratio of sediments in 40-73 cm section (LGM-Early Holocene). Between 35 and 40 cm, at the beginning of Holocene, a significant reversal in the climate from humid to arid, and associated decrease in the monsoon intensity is interpreted