Proximal-to-Distal Evolution of Granite-Related Sn Mineralization at Xianghualing, South China: Constraints from Cassiterite U–Pb Geochronology and Geochemistry

Distal, structure-controlled sulfide-type Sn mineralization is widely developed in granite-related Sn systems, but its genetic relationship with proximal intrusion-related mineralization remains poorly understood. The Xianghualing Sn deposit in the Nanling region, South China, contains both proximal skarn-type and distal sulfide-type Sn mineralization, providing an excellent opportunity to investigate their genetic linkage. Here, we combine cassiterite U–Pb geochronology and trace element geochemistry to constrain the timing, evolution, and genetic relationship of these mineralization styles. Cassiterite U–Pb dating yields ages of 154.9 ± 2.5 Ma for skarn-type Sn mineralization and 150.1 ± 1.7 Ma for sulfide-type Sn mineralization, indicating that both formed during the late-stage evolution of the Laiziling granite. Cassiterites from both ore types show comparable granite-related geochemical signatures, including elevated Fe and W contents, high Zr/Hf ratios, and depletion of Nb and Ta, suggesting derivation from evolved magmatic–hydrothermal fluids. We propose that sulfide-type Sn mineralization represents a distal expression of the same evolving granite-related magmatic–hydrothermal system responsible for proximal skarn mineralization. Interlayered fracture zones and unconformities acted as preferential pathways for hydrothermal fluid migration and cassiterite precipitation. These findings highlight the importance of structural focusing during the evolution of granite-related Sn systems and provide new insights into exploration of concealed Sn mineralization in the Nanling region.