Petrogenesis of the Xinpengling A-type granite in the Yangchun Basin, South China: Insights into magma sources, evolutionary processes, and implications for W-Sn mineralization potential

• The Xinpengling granite (80 Ma) is a reduced, F-rich A-type granite formed in a Late Cretaceous extensional setting • Magmatic evolution (fractional crystallization, low f O 2 , F-enrichment) promoted W-Sn concentration in the melt. • Isotopic data reveal a juvenile source limiting initial Sn-W endowment compared to giant deposits. • Source composition is a pivotal factor, alongside magmatic processes, in controlling regional W-Sn mineralization potential. Highly fractionated granites are commonly associated with W-Sn mineralization, with magmatic evolution processes such as fractional crystallization and oxygen fugacity traditionally viewed as key controls. However, increasing studies have indicated that magma source characteristics also play a critical role in governing the potential for W-Sn mineralization. This study investigates the Xinpengling granite, a highly fractionated intrusion in the Yangchun Basin, South China, through integrated petrography, zircon U-Pb geochronology, whole-rock geochemistry, mineral chemistry, and Sr-Nd-Hf-O isotopic analyses to constrain its petrogenesis and implications for W-Sn mineralization. Zircon U-Pb dating reveals a crystallization age of 79.9 ± 1.1 Ma. The granite exhibits A-type affinities, characterized by high alkali contents, 10,000 × Ga/Al ratios (> 2.6), and HFSE enrichment, with zircon saturation thermometry indicating high formation temperatures (∼ 804 °C). Mineral chemistry reveals the presence of Fe-rich biotite with appreciable F content (up to 2.04 wt%), alongside F-dominant apatite (fluorapatite, F = 2.54–3.22 wt%; F/Cl > 100), indicating the F-enriched magmatic condition prevailing during the crystallization process. Whole-rock ε Nd (t) values (−8.24 to − 5.43) and zircon ε Hf (t) values (−3.83 to 0.04), with corresponding two-stage Nd (T DM2 = 1325–1554 Ma) and Hf (T DM2 = 1141–1386 Ma) model ages, coupled with zircon δ 18 O (7.1–7.5‰), indicate the magma derivation from partial melting of Mesoproterozoic crustal sources with mantle-derived input. The magmatic evolution is characterized by extensive fractional crystallization, as evidenced by high Rb/Sr ratios and pronounced negative Eu anomalies (δEu = 0.22–0.34), reduced oxygen fugacity indicated by low zircon Ce 4+ /Ce 3+ ratios (mean = 22.5) and negative ΔFMQ values (average − 2.0), and F-enrichment, all promoting W-Sn concentration. Nonetheless, compared to granites from giant W-Sn deposits (e.g., Gejiu, Dachang, Zhuxi) with more negative ε Hf (t) (−9.9 to − 3.7) and higher and variable δ 18 O (6.8–10.9‰), the Xinpengling granite’s higher ε Hf (t) and lower δ 18 O suggest a less evolved, less supracrustal metasediment-dominated source. The less mature metasedimentary material from the source may have likely resulted in a lower initial budget of W and Sn, limited the overall extraction and enrichment efficiency of Sn-W during the partial melting stage. These findings underscore that although magmatic processes enhance W-Sn enrichment in reduced granitic systems, source characteristics also influence mineralization potential, implying moderate Sn prospects for the Xinpengling granite and highlighting source heterogeneity in the regional metallogeny of South China.