Sphalerite geochemistry of the Zn-Pb orebodies in the Taebaeksan metallogenic province, Korea

Abstract

The Taebaeksan region, located in the northeastern part of South Korea, is an important metallogenic province which hosts numerous Zn-Pb-W-Mo-Fe-Cu (-Au-Ag) mineral systems. The Zn-Pb orebodies in the region (inclusive of skarn, carbonate replacement, and vein-breccia ore types) are hosted on the early Paleozoic carbonate sequences and they are associated with late Cretaceous to early Paleogene magmatic-hydrothermal activities. We collected Zn-Pb orebodies from 15 areas including non-metal deposits, such as high-Ca calcite marble, as well as exploration sites in the Taebaeksan metallogenic province. Thereafter, we studied the geochemistry of the sphalerite present in them to understand the regional Zn-Pb mineralization process and to establish an exploration strategy. The sphalerites collected from the region contained detectable amounts of Fe, Mn, Cd, Co, Cu, Ga, Ge, Mo, Ag, In, Sn, Sb, W, Tl, Pb, and Bi which were identified using microbeam techniques like EPMA and LA-ICP-MS. Sphalerites from economically significant Zn-Pb deposits characteristically have high Mn and low Cd content, while W (-Mo)-bearing deposits have remarkably high Cd content. Correlation trends between trace elements demonstrate the coupled substitution mechanisms such as 3 Zn2+ <-> 2 (Cu+ or Ag+) + Sn4+ and 2 Zn2+ <-> Cu+ + In3+, occurring in the sphalerite. High-temperature ores such as skarn and vein-breccia are relatively enriched with Co and In, while Ga, Ag, and Sn tend to be concentrated in the relatively low-temperature ores, such as carbonate replacement type ores. Lead isotope compositions of the sphalerites show a well-defined, positive, linear trend with those of the local Cretaceous intrusions and the sedimentary sequence of the Taebaeksan region. Major economic Zn-Pb deposits show relatively more signatures of non-radiogenic Pb isotope closer to the intrusions, as compared to the minor and sub-economic Zn-Pb orebodies. The Pb isotope signature suggests that Cretaceous magmatic-hydrothermal fluids with a minimal degree of fluid-rock interactions are required for economic Zn-Pb mineralization in the Taebaeksan metallogenic province.