南岭西段越城岭地区加里东期锡成矿作用OA北大核心CSTPCD

The Yuechengling area,situated in the western segment of Nanling metallogenic belt,is recognized as one of the crucial Caledonian W-Sn mineralization prospective zones in South China due to its superior metal-logenic geological conditions and dense distribution of mineralized occurrences.A systematic investigation into its petrogenesis-metallogenic coupling mechanisms is indispensable for both theoretical research and achieving exploration breakthroughs.This study focuses on Tongyoucun tin deposit and its ore-forming granites as key re-search subjects.A systematic investigation is conducted,encompassing petrological analyses,zircon U-Pb and cassiterite U-Pb geochronology,whole-rock geochemical studies,and exploring their genetic relationships with tin mineralization.Geochemical results reveal that the granites in mining area exhibit SiO2 and K2O contents of 76.00％-77.66％and 4.78％-6.64％respectively,with an aluminum saturation index(ASI)of 1.16-1.68 and a differentiation index(DI)of 88.77-95.10,classifying them as the highly fractionated S-type granites within the strongly peraluminous high-K calc-alkaline series.The zircon and cassiterite U-Pb dating results show that the intrusion age of granite is 438.0±10.0 Ma.The tin-bearing greisen-type and fracture-zone vein-type cassiterite U-Pb ages in mining area are 429.1±3.4 Ma and 413.5±4.1 Ma,respectively.These data in-dicate that both magmatic intrusion and tin mineralization events occurred during Late Caledonian period,with mineralization slightly postdating the granite emplacement.The significant temporal gap between tin mineraliza-tion stages suggests the existence of two-stage tin mineralization events in Tongyoucun area,potentially linked to late-stage intrusions related to tin mineralization at depth.Petrogeochemical characteristics indicate that the granites in mining area are formed during the post-collisional tectonic setting of orogenic compression-to-exten-sion transition phase,representing a product of partial melting of ancient crust enriched in clay-rich metapelitic rocks.Comprehensive studies reveal that Caledonian magmatic activity in Yuechengling area can be subdivided into six phases,corresponding to five W-Sn mineralization events.Late-stage intrusions exhibit a specific metal-logenic affinity with W-Sn mineralization.