Exploring the Sn–W metallogenic potential of Late Jurassic Ganfang-Guyangzhai granite suite, South China: Zircon and apatite geochemistry

Abstract

Many Late Mesozoic granitoids in South China are associated with the mineralization of tungsten and tin metals. Ore deposits associated with granitoids are key sources of a number of economically important metals, for instance of W and Sn. The significant controls on magma metal fertility are magmatic sources, degrees of differentiation, oxygen fugacities, and halogen contents. Investigating the factors and their metallogenic potential is essential for future exploration. To this end, this study presents new zircon and apatite data for the Late Jurassic ca. 145 Ma Ganfang-Guyangzhai granite [GF–GYZ] suite and nearby coeval Shiqiao [SQ] granitoid intrusion near the giant Dahutang tungsten ore deposit. We explore the metallogenic potential in terms of the studies on oxygen fugacity and halogens in melts. These granitoids have similar zircon δ18O values (SQ: 8.39‰–9.74‰; GF–GYZ: 8.70‰–10.7‰). However, SQ granitoids are more oxidized than GF–GYZ granitoids, with zircon logƒO2 values of −18.5 to −8.1 and −24.5 to −16.8, respectively. Apatite grains in these granitoids all have high F (>1.7 wt%) and low Cl (<0.05 wt%) concentrations, yielding extremely low Cl/F ratios (<0.021), which are within the range for tungsten-bearing granitoids worldwide (Cl < 0.5 wt%, Cl/F < 0.02). Furthermore, the more evolved GF–GYZ granitoids show relatively high F (2.26–2.75 wt%) concentrations, which are more similar to granites directly associated with the Dahutang tungsten ore deposit in terms of their magmatic sources, degrees of differentiation, oxygen fugacities, and halogen contents. These geochemical similarities suggest that the GF–GYZ granite intrusions also have significant metallogenic potential for tin and tungsten deposits.