Phosphorite occurrences on the western continental margin of India: An update

Abstract

Marine phosphorites are well known from the tropical upwelling zones along the west coast of North America, South America, and African continents. Despite having similar oceanographic and topographic set-ups, comparable scales of phosphorite occurrences have not been reported from the western margin of the Indian subcontinent. However, Seabed surveys carried out by the Geological Survey of India during the last decade unearthed phosphatic crusts and nodules from several elevated topographic domains off the west coast of India. These new findings necessitate an update to the phosphorite zone map of the present-day Ocean. On the seamounts and spurs off the west coast of India, ferruginous and non-ferruginous phosphorites occur in the form of crusts and nodules within the water depth range of 300 to 800 m. Geochemical evidence and concurrent occurrences of varied types of phosphorites within the same topographic domain point to the prevalence of multiple episodes of short-duration phosphogenesis along the western margin of India.