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

S. D. Iyer ¹, M. Sudhakar ¹

Affiliations
1 Geological Oceanography Division, National Institute of Oceanography, Dona-Paula, Goa - 403 004, IN

Abstract

Based on various lines of evidence such as the widespread occurrence of basalts. pumice. volcanic glass shards and their transformational products (zeolites, palagonites, and smectite-rich sediments), we suggest the presence of a volcanic province in the Central Indian Basin (CIB). In addition to the rocks studied, the occurrence of many morpho-tectonic features such as seamounts, abyssal hills and major fracture zones at 73°E, 75°45'E and 79°E, have helped in correlating and in deciphering the source of the rock types. Further, the large manganese nodule fields in the CIB are seen to occur in conj unction with the volcanic materials, since the latter forms nuclei and substrates for ferromanganese deposits. It is concluded that a spatial relation exists between the occurrence of the volcanic materials and the ferromanganese deposits in the CIB.

Keywords

Marine Geology, Ferromanganese Deposits, Volcanism, Central Indian Basin.

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Uma Shankar ¹, Maheswar Ojha ¹, Kalachand Sain ¹, Ramesh Khanna ¹, M. Sudhakar ², Abhishek Tyagi ²

Affiliations
1 National Geophysical Research Institute, Hyderabad-500007, IN
2 National Center for Antarctic and Ocean Research, Headland Sada, Goa-403804, IN

Abstract

New data have been collected using the multibeam echosounder (Hydrosweep) and high resolution subbottom profiler (Parasound) systems in deep water of the Western Continental Margin of India (WCMI) during the 41^st cruise of R/V Academic Boris Petrov from 17 to 26 November, 2006. The six meters gravity coring along with CTD (Conductivity-Temperature-Depth) measurements are also carried out. Two sites in the Saurashtra and Kerala-Konkan offshore basins have been covered to find out features related to gas hydrates during this short cruise. High resolution multibeam echosounder and sub-Bottom profiling delineate the fine-Scale structure of the sedimentary layer of about 50-100 m thickness below the seafloor. Gravity corer is operated at five stations, out of which four gravity cores of more than 5 m length are recovered successfully. Gas and pore waters from cores have been collected for performing the laboratory studies. The Rosette system is used for temperature and salinity measurement in the water columns. The gravity cores collected on sites show the evidence of sediment fluidization and contain certain amount of gas. The gas is collected from sediments using the technique developed in the V.I.Vernadsky Institute of Geochemistry and Analytical Chemistry for the chemical and isotopic analysis for future research. The preliminary results show that the continental slope and rise of the oceanic margin of the Western India are prospective for exploration of gas hydrate. The more definite conclusion can be drawn after carrying out laboratory studies.

Keywords

WCMI, Gas Hydrates, Hydrosweep, Parasound, and CTD.

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