Distribution of Co, Se, Cd, In, Re and other critical metals in sulfide ores from a porphyry-skarn system: A case study of Chengmenshan Cu deposit, Jiangxi, China

Abstract

Chengmenshan Cu deposit is a large porphyry-skarn copper deposit, located in the Jiutui ore district, Middle–Lower Yangtze River metallogenic belt, Eastern China. The deposit is enriched in tellurium, selenium, rhenium and cadmium; however, the occurrence and distribution of these metals are unclear. In this study, we report cobalt, selenium, cadmium, indium, rhenium and other critical metals in pyrite, chalcopyrite, and sphalerite from sulfide ores of Chengmenshan deposit. In-situ LA-ICP-MS trace element analysis and mapping of minerals were conducted to determine their trace element concentrations and reveal the distribution and occurrence of critical metals in different sulfides. Three ore types have been identified in Chengmenshan deposit, named: porphyry ore, skarn ore and strata-bound ore. Based on mineral assemblages, ore fabrics, and crosscutting relationships between the veins, Chengmenshan deposit is divided into three mineralization stages: pre-ore stage of skarn mineralization, syn-ore stage of sulfide mineralization, and post-ore stage of carbonation. The pyrite and sphalerite can be divided into two generations: Py1, Py2, and Sp1, Sp2, respectively. The critical metals exhibited an uneven distribution and closely related to sulfide minerals. Telluride minerals in the deposit mainly include hessite, tetradymite, joseite. Rhenium is mainly enriched in molybdenite (128 to 496 ppm, average 276 ppm); cobalt is mainly enriched in pyrite, and the value of the three types of ore in the early stage (Py1) higher late stage (Py2); Se in chalcopyrite is slightly higher than pyrite and sphalerite; Cadmium is mainly enriched in sphalerite (up to 3000–6000 ppm), and is relatively low in pyrite and chalcopyrite; Indium is distributed in chalcopyrite and sphalerite, and the values of sphalerite are higher than chalcopyrite; the Ga distribution was sphalerite > chalcopyrite > pyrite. The enrichment and distribution of Co, Cd, In in Chengmenshan porphyry-skarn deposit system were mainly control by the fluid temperature. The Cu-Mo (Re), Cu-Fe (Co, Se) and Cu-Pb-Zn-Ag (Te, Cd, In, Tl) mineralizations constitute Chengmenshan porphyry-skarn mineralization system, and show a Mo-Re to Cu-Co-Se-Te-Ga to Cu-Pb-Zn-Ag-Te-Cd-In pattern from granite to distal stratum in space.