Magmatic–Hydrothermal Evolution at the Barren Wushan Pluton, Southeast China: Insight into Controls on Mineralization Potential.

This article focuses on the magmatic evolution and mineralization potential of molybdenum (Mo) and tin (Sn) in the barren Wushan pluton, a Late Cretaceous A-type granite in South China. Detailed melt and fluid inclusion analyses reveal that Mo behaves as a highly incompatible element, becoming enriched during fractional crystallization until fluid saturation leads to Mo-bearing fluid exsolution, while Sn shows limited enrichment due to sequestration in crystallizing minerals and low partitioning into exsolving fluids. Comparative data from mineralized and barren intrusions indicate that metal concentrations in melts and fluids are similar, suggesting that physical factors—such as melt viscosity, magma chamber volume, and structural features like apophyses that facilitate fluid extraction and focusing—play a more critical role in Mo mineralization than metal content alone. For Sn, significant enrichment in initial exsolving fluids, rather than in melts, is identified as a necessary and sufficient condition for mineralization, with melt-fluid partitioning efficiency being decisive. The study implies that the coastal A-type granite belt in South China has potential for Mo exploration but limited prospects for Sn mineralization.