Skarn Zn-Pb metallogeny in the Tianshan: Spatiotemporal distribution, geological characteristics and genetical model

The Tianshan orogenesis was initiated as a dynamic response to the subduction of several branches of the Paleo-Asian Ocean (PAO) and formed a significant polymetallic metallogenic belt in the western Central Asia. Skarn-related Zn-Pb deposits occupies an essential position in Zn-Pb mineral resources of the Tianshan, but its genesis remains ambiguous, and its economic importance is substantially undervalued. Here, we present a compre-hensive overview of the spatiotemporal distribution, geological characteristics, geochemical characteristics of causative intrusions, fluid inclusion geochemistry, H-O-C-S-Pb isotopic systematics to constrain the tectonic setting, source and metallogenic mechanism of skarn Zn-Pb deposits in the Tianshan. Our study suggests that the 380-320 Ma and 350-300 Ma skarn type Zn-Pb mineralization occurred in the Tianshan is temporally and genetically related to the Late Paleozoic subduction of the PAO. The skarn type Zn-Pb resources are primarily hosted by distal skarns, with causative intrusions characterized by calc-alkaline to high-K calc-alkaline, per-aluminous, and oxidized rock series that originated from partial melting of depleted mantle wedge and meta-somatized by subducted sediment or sediment-derived melts. The hydrothermal fluids that enriched with ore -forming elements were mainly released from the causative intrusions and channeled along interlayer fracture structures within the host rocks, where Zn-Pb mineralization took place due to fluid-rock interaction and fluid mixing. Finally, the mineralization model established in this study may be used to evaluate similar skarn Zn-Pb mineralization systems elsewhere in the Tianshan.