Two pulses of mineralization and genesis of the Zhaxikang Sb–Pb–Zn–Ag deposit in southern Tibet: Constraints from Fe–Zn isotopes

The Sr–He–Ar isotopic and elemental evidence constraints on the ore genesis of the Zhaxikang Sb–Pb–Zn–Ag deposit in southern Tibet

“…The ores in Stage 2 exhibit banded (Figure d), massive (Figure e,f), globular (Figure e), and concentric annular (Figure f) textures. Concurrently, previous studies of Zhaxikang deposits also found the disseminated, brecciated, fine‐grained layered and colloform, net‐veined, and Dal Matianite ore textures (Wang et al, ; Wang, Zheng, Mathur, & Wu, ), as well as syndepositional structure and even ancient hydrothermal vent (Zheng et al, ) in the first episode of mineralization. The above characteristics of the ores from the first episode of mineralization in Zhaxikang deposit are similar to those of the ores from Red Dog SEDEX‐type ore district in Alaska, which reveals typical submarine hydrothermal sedimentation (metasomatism) origin.…”

“…The second episode of mineralization has overprinted the first episode of mineralization. This overprint influenced the Mn–Fe carbonate, which lead to the recrystallization of some Mn–Fe carbonate ores (Wang et al, ; Wang, Zheng, Mathur, & Wu, ). However, from the Sr isotopic two‐component mixing model (Figure c), the Sr isotopic characteristics of Mn–Fe carbonate have little influenced by the second episode of mineralization.…”

“…Detailed regional settings of NH have been reported in the previous literature (Wang et al, ; Wang, Zheng, Mathur, & Wu, ; Sun et al, ; Zhou et al, ), here is only a brief description. The strata cropping out in NH mainly include the Precambrian Laguigangri Group and a series of Upper Triassic, Jurassic, Lower Cretaceous, and Quaternary sediments (Figure b).…”

“…The second episode is prevailingly Sb–Ag mineralization and includes Stages 3 to 6. As the transitional stage between two episodes of mineralization, Stage 3 comprises an assemblage of quartz ± calcite + pyrite + sphalerite + galena ± chalcopyrite ± arsenopyrite (Figures g–i), and the sulphides in this stage mainly form by replacement of sulphides from the first episode of mineralization (Wang et al, ; Wang, Zheng, Mathur, & Wu, ). The Stage 4 is characterized by an assemblage composed of quartz + antimony–lead–silver sulfosalt minerals (boulangerite, jamesonite, bournonite, tetrahedrite, and andorite) with massive and needle‐like ore textures (Figures j).…”

“…Wang and Zhu () suggested that the non‐traditional isotopic research of ore‐forming elements (e.g., Fe, Cu, Zn, Cd, and Mo) can more directly constrain the ore genesis and restore the ore‐forming process than traditional isotopes (e.g., C, H, O, and S). Accordingly, Wang et al () and Wang, Zheng, Mathur, and Wu () studied the Fe–Zn isotopes of Zhaxikang deposit. According to the combined research of Fe–Zn isotopic fractionation models and geological evidence, the δ 56 Fe and δ 66 Zn values of the first episode of ore‐forming fluid are supposed to range from −0.5‰ to −1‰ and −0.28‰ to 0‰, respectively.…”