The intracontinental-extensional full-temperature metallogenic model: application for the prospecting breakthroughs at the Shuikoushan Orefield

[Objective] Abstract: The central Nanling metallogenic belt is a representative region of intracontinental magmatic-hydrothermal mineralization in South China. Large Pb-Zn-Fe-Cu-Au-Ag deposits like the Shuikoushan ore field are concentrated in this belt but largely exhausted at shallow levels after a century of mining, making the succession of deep resources increasingly difficult. [Methods] To guide deep drilling in those old mines, this study systematically analyzes the metal sources, ore-controlling factors, temperature-dependent hydrothermal zonation, mineralization styles, and metal associations as well as their spatiotemporal coupling relationships from the material, structural, thermal, and metallogenic domains. [Results] The material domain reveals that magmas derived from different crustal levels and undergoing variable differentiation processes carry distinct metal inventories. Highly differentiated S- and A-type granites are enriched in W, Sn, Li, Be, Nb, and Ta, whereas weakly differentiated and oxidized I-type granodiorites are enriched in Fe, Cu, Au, Pb, and Zn. The structural domain shows that the intersections of deep faults and reversed folds, together with the calcareous-siliceous interfaces, provide the principal conduits and traps for ore-forming fluids. The thermal domain indicates that ore-forming metals are unloaded sequentially with decreasing temperature away from the intrusion. Tungsten, tin, molybdenum, and bismuth precipitate in the high-temperature proximal zone, together with iron and copper in the medium-high-temperature zone, lead, zinc, and gold in the medium-temperature zone, and gold and silver in the low-temperature distal zone. The metallogenic domain integrates the above three domains into a coherent framework, which can be summarized as one center, two structures, three systems, and multiple metals. This framework explains why distinct mineralization styles are superimposed within a single ore field. [Conclusions] On this basis, we propose an intracontinental-extensional full-temperature metallogenic model. This model emphasizes that magmas from different crustal levels and with variable differentiation were collectively emplaced at the intersections of deep faults and reversed folds. They successively formed high-temperature pegmatite-greisen Li-Be-Nb-Ta (400~550 °C), medium-to-high temperature skarn-porphyry W-Sn-Fe-Cu (280~500 °C), medium-temperature skarn Pb-Zn (230~370 °C), medium-low-temperature hydrothermal filling-replacement Pb-Zn-Au-Ag (120~340 °C), and epithermal Au-Ag (100~140 °C) mineralization. Distinct metallogenic systems can overlap with each other at the same period. Application of this model to the Shuikoushan ore field achieved three prospecting breakthroughs, including the discovery of the IV-3 orebody cluster to the east of the F₂₂ fault at Kangjiawan via the "anticline + N faults" model, the recognition of high-temperature Cu-Au mineralization to the south of Kangjiawan anticline based on the development of full-temperature mineralization along each concealed intrusion, the identification of skarn-porphyry type Cu-Fe-Au mineralization to the deeper Laoyachao–Yagongtang area guided by the concept that mineralization in different temperature domains serves as mutual prospecting indicators. [Significance] These results suggest that South China still holds extensive exploration potential for nonferrous and rare metals. The intracontinental-extensional full-temperature metallogenic model can provide new exploration strategies and target directions within mature mining districts.