Role of crude oil in the genesis of Mississippi Valley-type deposits: Evidence from the Cincinnati arch

Sulfur Isotope Geochemistry of Sulfide Minerals

“…Thus, stable isotope data from sulfi de minerals from Mississippi Valley-type deposits should provide information about the source of sulfi de and its geochemical history. Stable isotope studies of Mississippi Valley-type deposits are dominated by sulfur isotope data from both sulfi de and sulfate minerals (Ault and Kulp 1960;Sasaki and Krouse 1969;Ohmoto 1986;Kaiser et al 1987;Richardson et al 1988;Kesler et al 1994;Appold et al 1995;Kesler 1996;Misra et al 1996;Jones et al 1996).…”

“…The lower values may refl ect formation from H 2 S derived either directly or indirectly from open-system bacterial reduction of sulfate. Kesler et al (1994) proposed that low δ 34 S H 2 S was derived from oil in the deeper parts of the basin for the Central Tennessee and Kentucky Mississippi Valley-type districts. This H 2 S ultimately would have been derived from the bacterial reduction of sulfate.…”

Zn-Pb Ores of Mississippi Valley Type in the Lycksele-Storuman District, Northern Sweden: A Possible Rift-Related Cambrian Mineralisation Event

“…A genetic link between hydrocarbons and mineralising fluids has often been proposed for MVT deposits [34] and references therein]. Besides creating an anoxic environment, the hydrocarbons may have provided reduced sulphur for sulphide deposition by the release of organically bound sulphur or by thermochemical reduction of sulphate from evaporate rock or seawater [35].…”

Origins and fates of H2S in the Cambrian and Ordovician in Tazhong area: Evidence from sulfur isotopes, fluid inclusions and production data

“…Although some pyrite in this area with d 34 S values as low as À17.3‰ may have originated from BSR, the H 2 S is clearly not of bacterial origin because d 34 S H2S values are significantly heavier those of the pyrites and calcites and replaced sulfate minerals were measured to have fluid inclusion homogenization temperatures >120 C (Cai et al, 2001a. Field observations indicate that there is no significant or small sulfur isotope fractionation during the cracking of oils to H 2 S (Orr, 1974;Kesler et al, 1994), which is supported by hydrous pyrolysis experiments on a sulfur rich shale (Amrani et al, 2012). Hence, the observation that H 2 S in the Ordovician has d 34 S values lighter than or close to the associated oils (Fig.…”