Paired Sulfur Isotopic Belts: Late Cretaceous-Paleogene Ore Deposits of Southwest Japan.

Abstract

Abstract:Sulfides from late Cretaceous-Paleogene ore deposits of the Inner Zone of Southwest Japan were analyzed for 34 S/ 32 S ratios (δ 34 SCDT values) on 5 samples from the Ryoke Belt, 18 from the Sanyo-Naegi Belt, 15 from the Uetsu-Kanto District and 47 samples from the Sanin-Shirakawa Belt. Together with the published data, the average δ 34 S values are calculated for individual deposits of the whole region; 109 localities for the ilmenite-series granitic belt and 56 localities for the magnetiteseries granitic belt.The sulfur isotopic ratios vary regionally rather than with sulfide species or types and commodities of the ore deposits. The δ 34 S values are generally negative in the fore-arc, ilmenite-series belt, and positive in the back-arc, magnetite-series belt. This regional variation is considered to reflect the ilmenite-/magnetite-series pairing of the genetically related granitic or volcanic activities, in which the positive δ 34 S ore sulfur was derived from a deep igneous source, but the negative δ 34 S sulfur was originated in biogenic sulfur of the accreted sedimentary complex. Within each terrane, δ 34 S values and mineral commodities vary locally, which is called domains in this paper. A few negative δ 34 S minima are observed in the Kinki, Hiroshima and Mino domains. These anomalies may have been brought by the most sediments-dominant granitic magmas generated within the accretionary sedimentary complex.The paired δ 34 S belts, called the Japanese-type pattern, may be unique to island arcs where their fore-arc sediments have been accreted in the arc-front associated with the back-arc rifting.

Bismuth minerals from the W–Mo–Sn deposits hosted in the Iwafune granitoids, Niigata Prefecture, Japan

“…Although cassiterite has been reported by Ishihara and Sasaki (2002), it was not found in the present study. Quartz is the only gangue mineral.…”

Reconnaissance study on sulfur isotopic ratios of lead-zinc ores from North Vietnam

“…Empirically speaking, ore sulfi des are generally ca. 2 per mil lower than the related rock sulfides in granitic terrains (Ishihara and Sasaki, 2002). With this regards, 5-6 per mil could be assumed for the host rhyolitic magma, which is similar to the values of the magnetite-series granitoids in the Japanese Islands (Sasaki and Ishihara, 1979 S depleted sulfur like the one in black shale to the source fl uids is most probable, yet we need further detailed sampling and microscopic and isotopic studies on representative ore deposits in the Cho Dien mine area.…”

“…In the Japanese Islands, sulfur of the late Mesozoic to Tertiary vein-and skarn-type deposits show corresponding 34 S values of the ores to those of the related granitic rocks Sasaki and Ishihara, 1979;Shimazaki, 1985;Ishihara and Sasaki, 2002). In North Vietnam, many small to middle size lead-zinc ore deposits occur mostly in Paleozoic sedimentary terrain to the north of the capital Ha Noi, and also one small deposit in Triassic rhyolites to the northeast of Ha Giang, very close to the Chinese border ( Fig.…”

山口県後期白亜紀防府バソリスの三次元形態：地質・岩石と重力異常からの推定

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