Bulk chemical composition of pelagic sediment samples from the Central Pacific Basin, GH 79-1 detailed survey area

During the ten R/V Hakurei-Maru cruises from 1984 through 1988 in the Northwestern Pacific island-arc area, a widespread occurrence of hydrogenetic iron-manganese crusts and nodules and hydrothermal manganese deposits were discovered. During shipboard survey, the wet iron-manganese minerals were stored with sea water in a refrigerator immediately after recovery from a sampler, in order to prevent mineralogical transformation on air drying. The subsamples, in both wet and air-dried conditions, were subjected to X-ray powder diffraction (XRD) analysis to ascertain structural stability upon dehydration. Powder samples dried at 110°C for 3 hours were analyzed for metal concentration by atomic absorption spectroscopy according to the Geological Survey of Japan (GSJ) standard analytical technique.