Zircon U-Pb Geochronology and Metallogenic Implications of porphyry bodyin Nanshanchachang , Southeastern Hubei Province

【Objective】 The Nanshanchachang area is located in the southern part of the Edongnan ore district and on the western margin of the Yinzu pluton, which has become a key prospecting area in southeastern Hubei in recent years.Multiple small porphyry bodies accompanied by favorable mineralization phenomena have been newly discovered in this area.Nevertheless, few studies have been carried out on the geochronology, geochemical characteristics and metallogenic potential of the small porphyries in this area. 【Methods】This study conducts a systematic zircon geochronology and geochemistry investigation on granodiorite porphyry and quartz diorite porphyry developed in the area. 【Results】The results show that the weighted mean zircon U–Pb ages of the two intrusions are 141.5 ± 1.1 Ma and 140.9 ± 1.5 Ma, respectively, which are consistent with the mineralization ages of Cu polymetallic deposits in the Edongnan ore district. Zircon Lu-Hf isotopes yield ε_Hf(t) values of –11.87 to –9.2 and –11.1 to –8.89, suggesting that the magma source is similar to that of the regional ore-forming intrusions, mainly derived from an enriched lithospheric mantle with crustal contamination during evolution. Zircons from granodiorite and quartz diorite porphyries display Eu/Eu* values of 0.69–0.78 and 0.67–0.80, Dy/Yb ratios of 0.18–0.27 and 0.18–0.24, 10000×(Eu/Eu*)/Y values of 4.59–8.66 and 4.98–12.40, and (Ce/Nd)/Y ratios of 0.001–0.004, comparable to zircons from ore-related intrusions in the Edongnan Cu polymetallic deposits. Zircon Ti-in-thermometer estimates yield crystallization temperatures of 678–775 °C and 708–774 °C.【Conclusion】Combined with zircon geochemistry, the calculated ΔFMQ values (+0.34 to +1.84 and +0.46 to +1.52) indicate that the magmas had relatively high oxygen fugacity.Such hydrous and oxidized magmatic conditions are favorable for suppressing early sulfide saturation and facilitating the late-stage enrichment and migration of chalcophile elements such as Cu, Mo, and Au. Integrating geochronological, isotopic, and geochemical evidence, the Nanshanchachang small intrusions exhibit typical ore-related porphyry characteristics with significant mineralization potential. Future exploration should focus on deep verification in structural intersections and carbonate contact zones to achieve breakthroughs in mineral exploration.