Ore genesis and geodynamic setting of the Lianhuashan porphyry tungsten deposit, eastern Guangdong Province, SE China: constraints from muscovite 40Ar−39Ar and zircon U–Pb dating and Hf isotopes
The Lianhuashan deposit has long been regarded as a typical tungsten porphyry deposit, located in the eastern Guangdong Province, in the Southeastern Coastal Metallogenic Belt (SCMB). LA–MC–ICP–MS zircon U–Pb dating of the quartz porphyry yielded a weighted mean 206Pb/238U age of 137.3 ± 2.0 Ma, which is interpreted as the emplacement age of the quartz porphyry. Hydrothermal muscovite yielded a plateau 40Ar/39Ar age of 133.2 ± 0.9 Ma, which is consistent with the zircon U–Pb age, suggesting that the tungsten mineralization is genetically related to the quartz porphyry. Combined with previous studies, we suggest that there is a 145–135 Ma episode linking the granitic magmas with W–Sn ore systems in the SCMB. Zircon eHf (t) values of the quartz porphyry are in range of − 3.8 to 0.9, and the two-stage Hf model ages (TDM2) are 1.1–1.4 Ga, which is younger than the basement rocks in the Cathaysia Block (1.8–2.2 Ga), signifying that the quartz porphyry was predominantly derived from melting of Mesoproterozoic crust containing variable amounts of mantle components. In combination with the newly recognized coeval alkaline/bimodal magmatism and A-type granites in eastern Guangdong, we suggest that the 145–135 Ma W–Sn metallogenic event of the SCMB is related to a geodynamic setting of large-scale lithospheric extension and thinning, which can be ascribed to melting of the crust caused by mantle upwelling, triggered by the oblique subduction of the Izanagi plate.