Holocene Paleoenvironmental Changes In The Marginal Marine Basin Of Great Rann Of Kachchh, Western India: Insights From Sedimentological And Mineral Magnetic Studies On A Similar To 60 M Long Core

We carried out sedimentological and mineral magnetic studies on a -60 m long core recovered from the central part of the Great Rann of Kachchh (GRK), a marginal marine basin, located on the western continental margin of India to understand the Holocene paleoenvironmental changes. We critically analysed the sedimentation pattern, sediment characteristics along with paleoclimatic signatures of global and regional relevance. In GRK basin, the sedimentation started in early Holocene (-10.6-9.3 kyr BP) under rapidly rising post glacial sea level with very high sedimentation rate (8.71 cm/yr to 2.37 cm/yr) which is also seen in several marginal marine basins across the globe. The abundant laminations, coarse grained sediment flux and environmental magnetic parameters (chi lf, S-ratio) suggests that the sedimentation occurred in developing monsoonal conditions under wetter yet fluctuating climate during this period. After -9 kyr BP, the environmental magnetic proxies show transition toward relatively wetter condition with peak at -6.5 kyr BP. This wetter climatic phase on the other hand corroborates with reduction of sedimentation rate to 0.46 cm/yr. This reduction in sedimentation rate under strengthening monsoonal conditions probably occurred due to rapid filling up of the basin on account of earlier high sedimentation in the basin. The sedimentation rate is reduced significantly after the onset of aridity at -4 kyr BP except a minor wet spell recorded during -1.5 to 1 kyr BP before drying of the GRK basin.