A GIS APPROACH TO IDENTIFY POTENTIAL ZONES OF POLYMETALLIC NODULES IN THE INDIAN OCEAN REGION

摘要

Mankind's quest for metals has been growing steadily and has resulted in expanding his search beyond land, that is, in the oceans. Being in the dissolved form, metals are also formed in the ocean in the form of polymetallic nodules. They are submarine rock concretions formed of concentric layers of Iron and Manganese hydroxide around a nucleus. Nodules contain manganese and iron, nickel, copper, cobalt, lead, molybdenum, cadmium, vanadium, titanium, cobalt and copper. Various factors influence the growth and occurrence of polymetallic nodules such as, an abyssal hill topography, water depth ＞4500 m, a low sedimentation rate in order of few mm/1000 yrs, an effective bottom water current. Due to their economic potential, it's needed to identify the potential zones of polymetallic nodules in the Indian Ocean. For this, GIS technology is used in which various factors affecting the occurrence of polymetallic nodules are considered. The methodology adopted includes collection of maps and statistics about the study area and digitization of bathymetry, sedimentation types, a sedimentation thickness, physiographic and ocean currents map. Ranks and weights were assigned to the themes and sub themes and overlay analysis was performed to find the potential polymetallic zones .And it is seen that the central Indian Ocean basin (CIOB) region and certain other linear patches on the western side of the study area have good potential.