Palaeoclimatic and sea-level fluctuations from the last deglaciation to late Holocene from western India: Evidence from multiproxy studies

Abstract

• At least 4 episodes of marginal marine sedimentation environments are reported between last deglaciation to the late Holocene in Western India.. • The first phase of deposition under marine influence is at ~20 ka BP, the second phase between ~11,210 and 9759 cal yr BP and third phase of sea level rise at around ~6118 cal yr BP. The final phase of marine to marginal marine conditions are noted to be of post ~2650 ± 180 cal yr BP until ~1530 ± 350 cal yr BP. • There were coeval dry climatic conditions of the Older Dryas and Younger Dryas periods besides the warm and humid conditions of the Bolling-Allerod period. • During the last deglaciation to late Holocene times, at several times the Gulf of Kachchh extended inland and the rivers debouched into these extended gulfs rather than in the Little Rann as seen at present. A sediment core from a palaeochannel distributary of the Saraswati River basin in western India was investigated through a multi-proxy study using palynology, phytoliths, sedimentology, geochemistry, magnetic mineralogy and chronology. The site is located at the eastern margin of the Little Rann of Kachchh in the northwestern part of the Gujarat Alluvial Plains. The goal was to reconstruct the paleoclimatic and sea level flucutations spanning from the last deglaciation to the late Holocene in the area. The core records suggest at least four episodes of marginal marine environment between the last deglaciation and the late Holocene. The first phase of sediment deposition under marine influence was observed post LGM. The signatures of coeval dry climatic conditions of Older Dryas and Younger Dryas periods besides warm and humid conditions of Bølling-Ållerød period are reflected in the core records. The second phase of rise in sea level occurred between ~11,210 and ~9795 cal yr BP, which falls within the period of high gradient of sea-level rise of western India. The third phase of global sea level rise in the area is at around ~5747 cal yr BP which coincides with a high sea level phase along the west coast of India. The final recurrence of sediments with predominant marine signatures post ~2650 ± 180 cal yr BP until ~1530 ± 350 cal yr BP suggests marine to marginal marine conditions in the area.