Changing depositional environments during the Late Quatrnary along the western continental margin of India
Abstract
Sedimentalogical and palaeoceanographic studies were carried out on two sediment cores collected within the Oxygen Minimum Zone (OMZ - between 150 to 1200 m water depth) along the western continental margin of India. The glacial to interglacial variations on a shallow core off Cochin, suggests that the average sedimentation rates were very high (~6 13.2 cm/kyr) and varied widely during the Holocene and the late Pleistocene. Grain size measurements reveal that the clay content varied with the Late Quaternary climatic changes, as inferred from the stable isotope studies. The boundary between the Stage 2 and 1 is marked by a pronounced increase in the flux to terrigenous clays and a fall in organic (C@dorg@@) and carbonate (CaCO@d3@@) content. The rapid sea level fluctuations during the deglaciation and the proximity of the core site to the continent during the lowered sea level, lead to a relatively high average sedimentation rate. Contrastingly, a core from the isolated topographic high off Goa showed relatively lower average sedimentation rates (~6 5.2 cm/kyr) during the Holocene and the late Pleistocene. The contrasting sedimentation features observed at two different locations within the same oceanographic regime underlines the fact that topographic features and proximity of the core site to the continent, controls the sedimentation rates during the late Quaternary.
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