Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

P. M. Mohan ¹, K. Shephard ¹, N. Angusamy ¹, M. Suresh Gandhi ¹, G. V. Rajamanickam ¹

Affiliations
1 Department of Industries and Earth Sciences, Tamil University, Thanjavur - 613 005, IN

Abstract

Quaternary landforms between Vedaranyam and Rameshwaram on the east coast of India show a wide range from inland sand dune, flood plain, estuary, delta, cusp, beach, coastal dune, barrier ridge, mud flat, tidal creek to mangrove. The study area has been classified into inland, beach and offshore regions to evaluate the variation in the distribution of grain size and the depositional environments. 147 sediment samples were collected using hand augur along the beach (53) and inland (37) environments, and by Van Veen grab in the offshore area (57). Grain size analysis indicates that the area may have extended approximately 25 km towards inland from the present-day low water mark. In those days, the coast must have developed by almost similar processes as acting at present in the nearshore environment, and the sea level oscillation may have been significant in the past. Further, based on the present day rate of sedimentation, it is suggested that the study area may have developed within the last 1,50,000 years B.P.

Keywords

Quaternary Sedimentation, Coastal Geomorphology, Palk Strait, Tamil Nadu.

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M. Suresh Gandhi ¹

Affiliations
1 University of Madras, IN

Abstract

No Abstract.

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M. Suresh Gandhi ¹, G. V. Rajamanickam ²

Affiliations
1 Department of Earth Sciences, Tamil University, Thanjavur - 613 005, IN
2 Department of Disaster Management, SASTRA Deemed University, Thirumalaisamudaram, Thanjavur - 613 402, IN

Abstract

In order to use foraminifera as a tool for siltation studies, benthic foraminiferal studies of both living and dead have been undertaken in the Palk Strait, East coast of India. Forty Two offshore sediment samples upto 10 m water depth in eight transects have been collected using Lafond-Dietz snapper. The study has yielded a total of 102 benthic foraminiferal species. It has been observed that benthic foraminifera are abundant at Mandaparn and Devipattinam transects with high diversity in living species while the Manalmelkudi transect has displayed less abundance with the low diversity. The living/dead ratio is 6.6 % in Manalmelkudi and 24.57 % in Devipattinam. Based on the living/dead ratio, the raté of sedimentation has been estimated to be more in the south of Manalmelkudi than in the north. Unlike in the adjacent Gulf of Mannar and Bay of Bengal, an abrupt reduction in the diversity of benthic foraminifera, abnormality in the shape and size of the tests of species of Lagena, Asterorotalia, Quinqueloculina, Spiroloculina, Pararotalia, etc., and the presence of agglutinated foraminifera in the Palk Strait, in fact, suggests the prevailing high turbidity and in turn siltation, leading to an unfavourable environment in the present study area.

Keywords

Benthic Foraminifera, Siltation, Palk Strait, Tamil Nadu.

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