Geomorphology and surficial geology of the western continental shelf and slope of India: A review

Abstract

Coastal geology and geomorphology of the area and nearshore currents played a significant role in the distribution of placer minerals off Kerala and Maharashtra. Transport and sedeimentation of fine-grained materials at places on the shelf are influenced by high-energy conditions. Clay minerals derived from the Indus, Deccan Trap basalt and Gneissic provinces are distinct along the inner shelf, but bypassed the outer shelf and got deposited on the continental slope. Relict biogenic carbonates comprising Halimeda litho-facies, rhodalgal-coral facies and molechfer facies, occur in the northern, central and southwestern shelf, respectively. Terrestrial limestones described as palaeo-shoreline indicators occur at mid-shelf. Several evidences exist in favour of Late Quaternary neotectonic activity and subsidence. Phosphorites and phosphatized limestones occur on the shelf and slope and phosphatization seems to be a short event in the Early Holocene. Vardine and Glaucony facies occur on the shelf and slope of the central and southwestern margin of India. Systematic sampling/radiocarbon dating is lacking on many geomorphic features. Some coastal bays in Maharashtra are least explored for heavy minerals. Phosphorites at places could prove economic, if detailed exploration is done. Several gaps exist inthe data on sea level changes during the Late Quaternary. Shelf edge exchange processes are to be studied in understanding the organic carbon distribution. Attention should be directed in solving the problems highlighted.