Holocene and Late Pleistocene relative sea level fluctuations along the east coast of India

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Abstract Hermatypic coral colonies and intertidal fossil bearing grainstone, packstone and sandstone beds of Holocene and of a Late Pleistocene highstand are exposed above the present High Tide Level (HTL) at a number of locations along the east coast of India from Cape Comorin to Rameswaram. Being a passive margin boundary, free from indications of Late Quaternary seismogenic movements, this sector provides a benchmark for defining minor relative sea level perturbations during the Late Pleistocene and Holocene highstands along a tropical coast lying between latitudes 5°N and 10°N. A series of marine terraces, carved on and locally blanketted by Late Pleistocene biotic and terrigenous accumulations, occur at different elevations (up to 4.4 m) above LTL at Manappad Point, possibly signifying discrete stillstand episodes followed by abrupt intervals of rising/falling sea level. Sea level indicators of the Holocene highstand occur in this sector, as well as along the fringes of the Godavari delta further north. The Holocene highstand reached nearly 3 m above LTL at 7.3 ka, remained stable for approximately 1.7 kyr and was followed by a relative sea level fall. Between 5.2 and 4.2 ka, there was a second pulse of relative sea level rise of a few metres leading to a fresh spurt in coral growth along the northern coast of Mandapam and Rameswaram. This was nearly contemporaneous with fresh melting of ice sheets of Antarctica. The Little Ice Age (LIA) witnessed a minor (>1 m) relative sea level fall along this coast, resulting in rapid diagenetic hardening and infiltration of goethite into the emerged foreshore sand at Karikovil and its neighbourhood. This was followed by a rise of the sea level during the last few centuries.