A multi-proxy approach for delineation of ferromanganese mineralization from the West Sewell Ridge, Andaman Sea

Abstract

Based on the Multibeam backscatter data, Sub-bottom profiling and Remotely Operated Vehicle (ROV) dives, an attempt has been made to understand the spatial distribution of ferromanganese crusts and nodules on the West Sewell Ridge (WSR), Andaman Sea. Slope analysis of the multibeam data and echo type characters from sub-bottom profiles were used to identify favorable areas for crust and nodule occurrence and these areas were selected for detailed seafloor feature analysis using ROV videography. Further, histogram analysis of backscatter intensity revealed five boundary values and integrated these threshold values with ground truth observation from ROV videos identified crust dominated, crust and nodule dominated, the hard substrate with thin sediment cover, the hard substrate with thick sediment cover, and complete sediment covered seabed. The seafloor variation map prepared from the different geological classes identified shows that crust-dominated seabed is distributed in the eastern summit region while crust and nodule-dominated seabed in the western summit region of WSR. Further, the flanks of the WSR are covered with turbidity sediments and sediments derived from the slope failure and possess the least possibility of the occurrence of crusts and nodules on the flanks.