| Research Abstract |
An integrated systematic study has been carried out on the earth's environmental and metallogenic histories, in the hope of verifying and further developing the author's original working-hypothesis linking derivation of both the syngenetic Kuroko-type heavy metal deposits and the crude oil deposits in the Miocene Green Tuff region of Japan to a common sedimentary organic source material named PUMOS presumably accumulated in association with an intense oceanic anoxia in the back-arc basin of paleo-Japan Sea. Present intensive sulfur isotope studies on some major biological mass extinction boundaries (PC/C, F/F, G/L, P/T, C/T and K/T) and also on some major time-restricted strataboud-type syngenetic mineralizations (Kieslager cupriferous pyritic deposits, bedded manganese deposits, and Kuroko-type massive sulfide deposits) from various localities in the world have revealed that these biological and metallogenetic events almost always concur with, or sometimes predate and/or postdate, the
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occurrence of intense oceanic anoxia throughout the geologic history This finding would provide evidence for the larger-than-expected intimate genetic relationship of the earth's environmental evolution to the economically important heavy metal mineralizations as well as hydrocarbon resource formation. Another important result is a fundamental contribution to the sulfur isotope stratigraphy. A number of analyses for the SSS (structurally substituted sulfate) of modern biogeic carbonate shells and skeletons (mollusks, brachiopods, urchins and corals) have yielded isotopic compositions similar to the average values of ambient dissolved seawater sulfates. This would provide sound evidence that the biogenic SSS in the geologic record can be utilized as a good proxy for the isotopic composition of ancient coeval seawater sulfate. Applying the SSS-based isotope stratigraphy to limestone sections (Cambro-Ordovician, Devonian, Carboniferous, Permo-Triassic, Cretaceous) from various localities in Asia and Europe, additional information has been successfully obtained to make up for the higher-order oceanic isotope evolution and the marine redox environmental change during the Phanerozoic time Less
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