In order to understand the origin of metal spherical minerals in the Okinawa Trough sediments, the authors have microscopically examined 215 samples (161 surface and 54 core samples) from 150 stations scattered in the shallow-sea continental shelf and trough areas,on the basis of the extensive studies of detrital minerals in the East China Sea continental shelf sediments. It is found that no metal spherical minerals occur either in surface or in core samples from sediments in the vast shallow-sea continental area, with an occurrence probability of zero, while in the narrow trough area the occurrence probability is 43% or more. And their distribution, either in. lateral or in vertical direction, shows an obvious regional speciality. This regional speciality is related to the assemblage type in which volcanoclastic minerals are predominant in the Okinawa Trough sediments, i.e., the occurrence probability of metal spherical minerals is proportional to the contents of pyroxene of volcanic origin and volcanic glass. A few metal spherical minerals are found enclosed within the volcanic glass. These facts strongly.indicate that metal spherical minerals in the Okinawa Trough sediments are of terrestrial rather than cosmic origin.
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