Subsidence of gold grains in allochthonous alluvial and coastal-marine placers |
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| Abstract: | An absolute-age determination of the tuffs, volcanic bombs, re-explosive fragments, lava flows, and extrusive rocks of the Korvunchana series of the central part of the Siberian Platform indicates that most of the volcanics appear to be older (P1-P2) than that assumed up to now (T1). Among the determinations, Late Permian dates predominate. Two determinations gave figures of 190 and 172 m.y., and one of 241 m.y. The age of the re-explosive fragments has apparently been underestimated (200-188 m.y.). The data indicate the presence of a lengthy break in the effusive-explosive volcanism during the course of a substantial portion of Triassic time.—Author. |
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