Development of manganese nodule resources in the Central Indian Ocean

Abstract

Resources evalution on grade and abundance of nodules using statistical methods for grab samples and photography data, combined with bathymetric and structural mapping, were carried out for delineation of the potential area of Central Indian Ocean. Results show that distribution of nodules is patchey (1 to 20 kg/sqm. abundance and 1 to 75% coverage), sizes are variable (less than 1 to 10 cm), and the burial is differential (0 to 100%), which are influencEd. by the seabed morphology and distribution of associated features, such as the sediments and rock exposures, on the seafloor. Geochemical, petrological, mineralogical and geochronological studies on nodules and the associated sediments have resulted in understanding the formation process of the deposits. Occurrence of megabenthic organisms (6 individuals /100 sq.m.) and their activities in nodule areas (4-12 traces/sq. m.), as well as geotechnical properties of the seafloor sediments have been evaluated. Studies on characterization of seabed from backscatter of multibeam data are uderway Time-series measurements on various oceanographic parameters in the claim area, have also been undertaken for collection of baseline information to evaluate the effects of mining during test and commercial mining operations. The requirements of specific data parameters have resulted in development of newer sampling methods, such as, corers with cameras and modified dredges, evolve techniques for data processing and cataloguing, as well as efforts at fabricating a multipurpose bottom lander equipment. The variety of data parameters collected are useful for designing the future mining system. Future program is aimed at dredging large quantities of nodules for testing of the metallurgical processing plant, detailed bathymetric mapping of potential mine-sites, geotechnical investigations and bottom photography with deeptowed TV system