Sulfur and oxygen isotopic geochemistry of sulfate in the black ore deposits of Japan

Abstract

Abstract-The sulfur isotopic values of barite, gypsum and anhydrite from the typical strata-bound submarine ore deposits (black ore deposits) of Miocene age in Japan have a narrow range of +21 to 24%o with respect to the meteoritic sulfur. However, the oxygen isotopic values (in SMOW) vary from +5 to +19%o and have a general tendency to increase in the order : barite < anhydrite -alabaster < secondary gypsum (satin spar and selenite). The sulfate minerals from the late Paleozoic cupriferrous iron sulfide ore deposits of the Yanahara and Besshi mines are similar in the sulfur isotopic values (+11 to +15%o) to inferred Permian sea water sulfate, whereas the oxygen isotopic values have a wide range of variation.The observed sulfur isotopic pattern is most likely due to a submarine hydrothermal system in which sulfate of marine origin (connate or actual sea water) predominated over other sources of sulfur. The variable oxygen isotopic data of sulfate are explained by the oxygen isotopic exchange between sulfate and water during depositional and post-depo sitional processes. The sulfur and oxygen isotopic ratios of "hot sulfate" in the Wairakei and the Red Sea geothermal brines are consistent with this idea.The sulfates in secor dary gypsum ores in the Noto mine are enriched in both 34Sand 180, suggesting that the alteration of the primary ores in this mine may have taken place under the influence of sulfate-reducing bacteria.

Oxygen and hydrogen isotopic study on the water of crystallization of gypsum from the Kuroko type mineralization

“…Gypsum ores in the Kuroko and Kuroko type deposits often consist of anhydrite and gypsum and the former tends to be concentrated toward the center of the ore bodies suggesting that anhydrite precipitated as a primary phase and later was hydrated to gypsum (MATSUKUMA and HORIKOSHI, 1970;KAJIWARA, 1971). The sulfur and oxygen isotopic ratios for sulfate of these gypsums are consistent with this view (SAKAI et al, 1970).…”

“…1) Except for the Noto gypsum and Recent evaporite, the 5180 values of sulfate in gypsum of the present study fall within a range from +6.5 to +13.0 %o (SAKAI et al, 1970 and unpublished data by H. SAKAI) and no definite correlation is observed between the 5180 values of sulfate and w.c.g. Three Noto gypsum samples (36,37,38) have the 5180 values of sulfate of +12.7, +14.9 and +17.1 %o, respectively (SAKAI et al, 1970), showing significant enrichment of 180 in sulfate as well as in the w.c.g. However, they are also significantly enriched in 34S, implying that the sulfates were subjected to extensive bacterial reduction (SAKAI et al 1970).…”

“…Three Noto gypsum samples (36,37,38) have the 5180 values of sulfate of +12.7, +14.9 and +17.1 %o, respectively (SAKAI et al, 1970), showing significant enrichment of 180 in sulfate as well as in the w.c.g. However, they are also significantly enriched in 34S, implying that the sulfates were subjected to extensive bacterial reduction (SAKAI et al 1970). The high 5180 values of the sulfates apparently resulted from the extensive bacterial reduction of sulfates and may not be directly connected to the high 5180 values of water (compare MIZUTANI and RAFTER, 1973 …”

“…Most of the gypsum ores are considered to have been deposited originally as anhydrite, and later hydrated to gypsum (SAKAI et al, 1970;MATSUKUMA and HORIKOSHI, 1970;KAJIWARA, 1971). However, questions are yet to be answered on the nature of the water of hydration and the geologic time and processes of hydration.…”

Oxygen and sulfur isotopic compositions of quartz, barite and sulfide minerals from the Sambo Pb-Zn-barite ore deposits, South Korea.

“…6345 vs 6180 plot for sulfate minerals. BK and GK: Barite and gypsum from the Kuroko ore, Japan (Sakai et al, 1970). BR: Barite of Rosebery, Tasmania (Solomon et al, 1969).…”