Sulfur Isotope Study on Hg and Sb Deposits in Japan

Abstract

. Sulfur isotope ratios of cinnabar from Hg deposits and stibnite, jamesonite and berthierite from Sb deposits in Japan are examined in order to understand metallogeneses of Hg and Sb deposits in Japanese island arcs. The studied Hg and Sb deposits include the Hg deposit at Yamato‐suigin (Honshu) and the Sb deposit at Ichinokawa (Shikoku) in the Southwest Japan arc. In addition, Hg deposits including Itomuka and Ryushoden in central Hokkaido and Hg and Sb mineralizations in Northeast Japan arc are examined. The δ34S values of cinnabar from the Hidaka‐Kitami district, central Hokkaido, including the Itomuka and Ryushoden deposits range widely, from ‐10 to +16 %o, the highest values encountered at the Samani deposit. The δ34S values of cinnabar from other areas in Japan range from ‐12 to +5 %o, having δ34S values higher than +2 %o from southwestern Hokkaido (Meiji deposit), Shikoku (Suii deposit) and Kyushu (Hasami and Yamagano deposits). On the other hand, the δ34S values of stibnite from all areas in Japan range from ‐14 to +5 %o, having positive δ34S values higher than +2 %o up to +5 %o from southwestern Hokkaido (Yakumo, Toyotomi and Teine deposits) and eastern‐central Honshu (Hachiman and Daikoku deposits). The variation in δ34S values of Hg and Sb deposits may reflect the variation in δ34S values of country rocks or variation in mixing ratio of sulfur extracted from the country rocks, sulfur derived from seawater sulfate, and sulfur derived from magmatic emanations. The relatively high δ34S values of cinnabar and stibnite higher than +2 %o from southwestern Hokkaido, eastern‐central Honshu and Kyushu are probably caused by contribution of volcanic emanation from arc magmas having positive σδ34S values, whereas the positive δ34S values of cinnabar higher than +2 %o from Suii deposit in Shikoku may be attributed to structurally substituted sulfate in limestone country rocks and/or sulfur derived from seawater sulfate. However, the wide range of the δ34S values of cinnabar from the Hidaka‐Kitami district, central Hokkaido, is difficult to explain at this moment. Other relatively low, negative δ34S values of cinnabar and stibnite, berthierite from other areas in Japan may be attributed to 1) incorporation of isotopically light sedimentary sulfur or sulfur derived from ilmenite‐series silicic magma, or 2) less contribution of volcanic emanation from arc magmas having positive σδ34S values.

Organic matters and acid‐sulfate alteration in Itomuka mercury mine, Hokkaido, Japan: Implications for the transportation and deposition mechanisms of Hg

“…In general, sedimentary rocks like shale and greywacke are enriched in Hg and contain several hundred ppm of Hg (Barnes & Seward, ) and the alternation of shale‐sandstone is better source rock of Hg than pure shale due to the large volume of pore fluids in sandstone (Krupp, ). Sulfur isotope ratios of cinnabar from Itomuka mine are negative values (δ 34 S = −9.0, −4.1, −3.0‰: Imai et al ., ) and suggests that sulfur in Itomuka mine was emanated from the basement rock, which is consistent with this interpretation on the origin of Hg and organic matters.…”

Crystal Chemistry and Genesis of Organic Minerals: A Review of Oxalate and Polycyclic Aromatic Hydrocarbon Minerals

“…Mercury deposits in Japan occur along the Median Tectonic Line and volcanic front (Imai et al 2006), which is similar in that mercury deposits in California are along the San Andreas Fault. Many mercury deposits in both Japan and California are epithermal deposits and associated with a subduction-zone setting, which implies the potential occurrences of PAH minerals in mercury deposits in Japan.…”

“…Recently, kerogen-like solidified organic matter was reported from the mercury ore at the Itomuka mine, Hokkaido, Japan (Echigo et al 2007b). The Itomuka mine is an epithermal mercury deposit formed during the Miocene-Pliocene (Imai et al 2006). Most mercury deposits in California were formed in the Pliocene (Bailey 1962).…”

Sulfur isotopic ratios and mode of occurrence of stibnite at the Hishikari epithermal Au-Ag deposit, Japan

“…However, sulfur isotopic values for stibnite at the Hishikari deposit have not been previously documented, except for one value of -0.2‰ reported by Imai et al (2006); this was not fully discussed in terms of the source of stibnite sulfur.…”

“…Sulfur isotope data for stibnite are a powerful tool for understanding the genesis of stibnite mineralization, in conjunction with other geological, mineralogical, and geochemical data (e.g., Robinson and Farrand, 1982;Gokçe and Spiro, 1991;Ishihara et al, 2000;Imai et al, 2006). However, sulfur isotopic values for stibnite at the Hishikari deposit have not been previously documented, except for one value of -0.2‰ reported by Imai et al (2006); this was not fully discussed in terms of the source of stibnite sulfur.…”