Distribution of tellurium, selenium, cobalt and gold in sulfide minerals: A case study of the Jiguanzui porphyry-skarn Au-Cu deposit, Eastern China

Abstract

In recent years, an increasing number of studies have reported the enrichment of Te, Se, and Co in magmatic-hydrothermal deposits in the Mid-Lower Yangtze River metallogenic belt (MLYRB), especially in Au-rich deposits. The Jiguanzui deposit, a representative porphyry-skarn Au-Cu deposit in the MLYRB, Eastern China, is characterized by significant critical metal (Te, Se, Co) association. Based on previous studies on critical metals distribution, this study presents trace element geochemistry of various sulfide minerals (chalcopyrite, bornite, sphalerite, molybdenite) through LA-ICP-MS analysis, aiming to reveal the distribution and modes of occurrences of Te, Se, Co, and Au among sulfide minerals in the Jiguanzui Au-Cu deposit. Analytical results indicate that, except for molybdenite, which hosts high concentrations of both Te and Se, pyrite and chalcopyrite generally have higher Te contents than bornite and sphalerite, whereas bornite and chalcopyrite exhibit relatively high Se concentrations. Cobalt and Au are dominantly hosted in pyrite and chalcopyrite, respectively, although the highest Au concentration up to 14 ppm was tested in pyrite. Principal component analysis of trace element contents, time-resolved LA-ICP-MS signal depth profiles, and trace element correlations suggest that Te is generally incorporated as silver and bismuth telluride mineral inclusions in the sulfides, whereas Se and Co are incorporated into the lattice of sulfide minerals. The intimate Pb-Bi-(Cu)-Au associations suggest that tiny mineral inclusions of native Au coexisting with either Cu-Bi sulfosalts or Pb sulfides or sulfosalts. Comparative analysis of the distribution patterns of Te, Se, Co, and Au in porphyry-skarn deposits within the MLYRB suggest that pyrite is the main Te-hosting sulfide mineral, whereas chalcopyrite is the major host for Se, which means Te hosted in pyrite is difficult to recover under current technologies. Pyrite and sphalerite are the major hosts of Co, and chalcopyrite is the main Au-bearing sulfide mineral in the deposits.