Mid-late Holocene climatic reconstruction from coastal dunes of the western Kachchh, India

Abstract

The present study focuses on the mechanism, climate, and sea-level implications of the coastal dune building activity in the eastern coast of Kori Creek (Gulf of Kachchh). Around 10 m thick dune is investigated using sedimentology, geochemistry, and optical chronology. This study suggests that the dune sediment that overlies the Tertiary Oyster Bed is dated to ∼4 ka. The grain size analysis and correlation of textural parameters of the inland dunes and coastal dunes showed no stark difference, revealing they were deposited during the same time. Further, the geochemical data generated from the samples of the coastal dune site represent semi-arid to semi-humid climate with increasing chemical maturity and weakening monsoon during the time of deposition. Based on the current erosion dune face and optical ages of the samples, it can be related that the Kachchh coastline was exposed due to the lowering of the sea level at the time of the deposition of coastal dunes. The sea must be at a lower level to attain a preferable condition for the deposition of dunal landforms. The lowering of the sea exposed the beach with sandy material, which got blown away in strong wind, leading to dunes deposition. The cold phase at ∼4.2ka became the most conducive environment of coastal dune formation.