Fluid inclusions, S isotopes, and Pb isotopes characteristics of the Kuh-e-Surmeh carbonate-hosted Zn-Pb deposit in the Zagros Fold Belt, southwest Iran: Implications for the source of metals and sulfur and MVT genetic model

摘要

The Kuh-e-Surmeh Zn Pb deposit is hosted by Upper Permian carbonate platform in the Zagros Fold Belt of southwestern Iran. The orebody is characterized by massive, vein, and banded textures. It is mostly composed of sphalerite, galena, and pyrite accompanied with minor barite. Homogenization temperatures of fluid inclusions in sphalerite and barite range from 94.7 degrees to 200.0 degrees C and 93.6 degrees to 198.0 degrees C, respectively. Fluid salinities of sphalerite- and barite-hosted inclusions vary from 8.1 to 21.3 wt% NaClequiv. and 10.5 to 22.6 wt% NaClequiv., respectively. The delta S-34 values of barite range from 11.2 to 11.9 parts per thousand, similar to those of gypsum of the Nar Member (+10.9 to +11.7 parts per thousand) in the Upper Permian sedimentary strata and different from the delta S-34 values of Jahani Salt Dome gypsum (+ 29.1 to + 30.5 parts per thousand), indicating that sulfur was derived from the Upper Permian evaporites. The delta S-34 values of galena and sphalerite range from -1.7 to -15.4 parts per thousand, compatible with bacterial sulfate reduction (BSR) of the Upper Permian evaporites. The Pb isotopic compositions of galena yield Pb-206/Pb-204 ratios from 17.942 to 18.340, Pb-207/Pb-204 ratios from 15.649 to 15.744, and Pb-208/(204) Pb ratios from 38.186 to 38.458, indicating an upper crustal lead source.