(Table 1) Compositions of magnetites and ferric hydroxides from sediments from DSDP Holes 31-301 and 31-296

Twenty-eight specimens of clastogenic magnetites and ferric hydroxides recovered by the "Glomar Challenger". from Cenozoic deposits in the deep-sea basins of the Japan and Philippine seas were examined using an electron probe.
Paragenesis of trace elements in these minerals suggests their source to be tholeiitic basalts of continental type and serpentinites. The latter may be an indication of the presence of an ophiolite complex within the deep-sea basins of marginal seas.