Formation of a granite-related Sn-Pb-Zn-(Ag) deposit from three discrete mineralization events around a common magmatic-hydrothermal center over a span of ∼45 million years at Changpu, eastern Guangdong, South China

Magmatic-hydrothermal Sn-(W) mineral- ization is commonly associated with Pb-Zn- Ag mineralization, forming Sn-polymetallic deposits that typically exhibit a zonation from proximal Sn-(W) to distal Pb-Zn-Ag, alongside a paragenetic sequence from early Sn-(W) to late Pb-Zn-Ag mineralization. Tra- ditional models generally propose that these deposits formed from a single magmatic- hydrothermal event characterized by con- tinuously decreasing temperatures. However, our study of the Changpu Sn-Pb-Zn-(Ag) deposit in eastern Guangdong, South China, reveals a more intricate mineralization his- tory. There, metal zonation results from three distinct mineralization events occurring over a prolonged period. The Sn orebodies at Changpu occur as cassiterite-tourmaline- quartz-(muscovite) veins and breccia zones in the central part of the deposit, whereas the Pb-Zn-Ag orebodies occur mainly as sulfide- (cassiterite) veins peripheral to the Sn ore- bodies. The hydrothermal processes related to mineralization are divided into three peri- ods, and each corresponds to a unique miner- alization event. Period 1 is characterized by tourmalinization with minor Sn mineraliza- tion, period 2 represents the main Sn miner- alization, and period 3 features predominant Pb-Zn-Ag mineralization. Different isotopic dating methods were used to obtain the ages of these mineralization periods: ca. 150 Ma for period 1 (U-Pb dating of cassiterite and Ar-Ar dating of fluid inclusions in quartz), ca. 130 Ma for period 2 (U-Pb dating of cas- siterite), and ca. 105 Ma for period 3 (Ar- Ar dating of muscovite). These ages over- lap with the reported zircon U-Pb ages for quartz porphyry dike (144.1 +/- 1.2 Ma) and rhyolite (153.9 +/- 1.3 Ma) in the deposit area. Fluid inclusions in cassiterite and quartz are of the H2O-CO2-CH4-NaCl compositional system in all of the periods and show a de- crease in temperature and salinity from the early to late stages within each period. The H isotopes of fluid inclusions in cassiterite and quartz fall within the field of magmatic water, and the O isotopes of the ore-forming fluids calculated from the O isotopes of cas- siterite and quartz are slightly shifted away from the field of magmatic water toward meteoric water. These geochronological and isotopic data, together with fluid pressures calculated from fluid inclusion data, suggest that three distinct magmatic-hydrothermal Sn-Pb-Zn mineralization events occurred at the same location over similar to 45 m.y., resulting in the observed metal zonation due to the evolu- tion of the magmatic system and continuous surface erosion. The magmas responsible for the three mineralization events are linked via deep fault to a crustal source region, where discrete partial melting processes are related to episodic slab-foundering or slab rollback of the paleo-Pacific plate during the Mesozoic in South China. This proposed model has significant implications for mineral explora-tion at depth within the study area and offers valuable insights for areas with similar geo- logical contexts globally.