The Federal Institute for Geosciences and natural Resources (BGR) has been exploring manganese nodules in a 75.000 km2 area in the central equatorial Pacific since 2006. The economic potential of the nodules results from their high and rather uniform Cu+Ni+Co content. Exploration activities focus on a detailed assessment of nodule abundance using a combined utilization of remote acoustic methods, close-up video mapping and selective box core sampling. In this paper, we briefly describe the technology used and present first results.
In 2006 the BGR has signed a 15-years contract with the International Seabed Authority (ISA) of the United Nations for the exclusive right to explore manganese nodules in a 75.000 km2 area in the central equatorial Pacific (Fig. 1). Based on three cruises carried out so far as well as on data from the 1970ies and 1980ies, it can be stated that most of the nodule samples have Cu+Ni+Co contents that scatter between 2.5 and 3.0% clearly indicating the overall appearance of valuable nodules in the license area. However, the nodules are not equally distributed on the seabed but their coverage changes irregularly. To assess the commercial viability of future nodule mining requires a detailed knowledge of nodule distribution of the investigated area. To explore vast areas of the seafloor as it is necessary for nodule exploration, methods with high resolution (such as video survey) must be linked with methods of low resolution (such as vessel-mounted survey).
For bathymetric mapping of the 75.000 km2 area the hull-mounted multibeam (swath) echosounding system Simrad EM 120 of Hawaiibased R/V Kilo Moana has been used in 2008 and 2009. It took us several weeks to prepare the first bathymetric map with total coverage of the exploration area (Rühlemann et al., 2009).
