Petrogenesis and Geochronology of the Dagang Muscovite-Granite in the Central Qinzhou-Hangzhou Metallogenic Belt, South China: Implications for Lithium-Enrichment Mechanism of Granite-Type Lithium Ore Deposit

The central Qinzhou-Hangzhou metallogenic belt in south China hosts large to supra-large hard-rock type lithium ore deposits. This contribution presents an integrated study of zircon U–Pb geochronology, whole-rock and in situ Lu-Hf isotopic geochemistry for the Dagang muscovite-granite type Lithium ore deposit. LA-ICP-MS zircon U–Pb dating of five muscovite-granitic samples yielded weighted average ²⁰⁶Pb/²³⁸U ages of 145 ± 3, 143 ± 1, 143 ± 1, 144 ± 3 and 144 ± 6 Ma, respectively, which are interpreted as the intrusion and mineralization ages of the granite. The Dagang granites have high SiO₂, Na₂O + K₂O and Al₂O₃ contents that are similar to those of strongly peraluminous granites. All the samples are depleted in Ba, Nb and Ti elements, but enriched Rb, Ta, Pb and U elements, as well as they have large negative ε_Hf(t) values of −11 ± 1.3, −8.1 ± 0.6, −6.7 ± 1.5, −8.6 ± 0.9 and −10.3 ± 2.3, which are indicative of dominantly Mesoproterozoic continental crustal metasedimentary in origin. There is no obvious correlation between SiO₂ and Li, whereas SiO₂/Al₂O₃ show negative correlation with Li, in combination with positive correlations of LOI, Rb, Cs and Li, as well as consensual genetic views of high-U zircons, it is proposed that lithium enrichment of the muscovite-granite type lithium ore deposit occurred late stage of crystallisation differentiation of silicic magmatic system during Al-rich mineral precipitation, and are superimposed of hydrothermal alteration.