CLAY MINERAL DISTRIBUTION IN THE CONTINENTAL-SHELF AND SLOPE OFF SAURASHTRA, WEST-COAST OF INDIA

Clay mineral distribution in the sediments of the west coast of India indicates that the illite and chlorite-rich sediments, derived from the Indus, occupy the continental shelf of the northern part of the Gulf of Kutch. Montmorillonite derived from the Deccan trap coastal province is the predominant clay mineral in the sediments of the continental shelf south of the Gulf of Kutch. Lateral variations reveal that the montmorillonite contents are high in the innershelf and on the continental slope with relatively low values on the outershelf. Illite and chlorite contents are high on the outershelf. These variations are attributed to the influence of depositional environment and individual property of the clay minerals. Distinct differences in the nature of montmorillonite derived from basic and gneissic rocks are identified. Review of the clay mineralogy suggests that their distribution is related to the provenance, and the latitudinal zonation of clay minerals may not be valid in this part of the Arabian Sea.