Surficial Sediments of the Continental Shelf off Karnataka

Abstract

The continental shelf in this area is about 80 km wide and the edge of the shelf varies between 90 and 120 m water depth. Geologically modern fine-grained clastic sediments occur between the water depth. Geologically modern fine-grained clastic sediments occur betweenthe water depths of 15 to 50m corresponding to a distance of about 40 km from the coast. Beyond 50 m to the shelf edge are calcareous sands. Non-carbonate components of these deep water sands are essentially quartz, many of which are heavily iron-strained and are attributed to the presence of rich iron formation on the land. The carbonate components in the outer shelf sediments are mainly foraminifers, pelecypods, gastropods, pteropods, and ooids, while ooids and pteropods are absent on the inner shelf. X-ray mineralogy of the silt fraction of the sediments shows the presence of quartz, calcite, aragonite and orthoclase as major minerals. Some of the sedimentary processes effecting the distribution of these sediments are discussed