摘要
Both tungsten(W)and tin(Sn)are crust-affiliated elements that tend to concentrate in highly fractionated granitic magmas.However,their mineralization is often decoupled,with some intrusions hosting predominantly W deposits while others being enriched in Sn.The mechanisms controlling this W-Sn mineralization decoupling remain unclear.This study investigates the role of fluorine(F)in this process by examining W-and Sn-mineralized granites in the Nanling Range,South China,with key findings as follows:(1)Sn-mineralized granites generally exhibit higher F contents(up to several thousand ppm)than Wmineralized granites(100–700 ppm),representing high-F and moderate-F magmatic systems,respectively.(2)Elevated F enhances the solubility of H2O and chlorine(Cl)in silicate melts,which inhibits fluid exsolution and premature Sn extraction,thereby enabling Sn enrichment in highly evolved melts to form Sn deposits.In moderate-F systems,early fluid exsolution at deep crustal levels leads to Sn loss in the form of stable Sn-Cl complexes to the fluid phase,leaving residual melts to form Wdominated deposits.(3)The higher F content in Sn-related magmas is attributed to inputs of volatiles associated with mantlederived mafic magmas.(4)Sn-mineralized granites can be classified as crust-mantle hybrid“H-type”granites associated with the flux of mantle-derived melt across trans-crustal magmatic systems.In contrast,W-mineralized granites are predominantly crustderived“C-type”granites produced by either heat-induced melting(magmatic underplating)or decompression melting with limited mantle contribution.We propose that the difference in F content essentially governs W-Sn mineralization decoupling.Future research should focus on the identification of deep mantle halogen reservoirs beneath Sn-polymetallic provinces and experimental investigations into the geochemical behavior of halogens,W,and Sn in magmatic-hydrothermal systems.
基金
supported by the Deep Earth Probe and Mineral Resources Exploration-National Science and Technology Major Project(Grant No.2024ZD1001501)
the National Natural Science Foundation of China(Grant Nos.42173053,41911530106,92162210)
projects from China Geological Survey(Grant Nos.DD20250208902,DD20221695)。
