Zircon U-Pb ages and Hf isotopes of the granitoids in the Huangshaping mining area and their geological significance

The Huangshaping polymetallic deposit is the largest lead-zinc mine in Hunan Province. There are various kinds of magmatic rocks distributing in this mining area, associated with W-Sn-Cu-Pb-Zn-Ag polymetallic mineralization. It's also a reprensitative deposit in southern Hunan with porphyry-skarn-vein Cu-Pb-Zn-Ag and W-Sn polymetallic superimposed mineralization. To clarify the geochronological framework and source characteristics of Huangshaping granitoids, and to address the temporal relationship between magmatism and mineralization, three types of granite including dacite porphyry, monzogranite porphyry and quartz porphyry, and the enclaves hosted in the quartz porphyry in Huangshaping were collected for zircon U-Pb dating and Hf isotope analysis. The results show that the zircon U-Pb ages of the dacite-porphyry, monzogranite porphyry and quartz porphyry are 158. 5 +/- 0. 9Ma, 155. 2 +/- 0. 4Ma and 160. 8 +/- 1. 0Ma, respectively. The zircon U-Pb age of the enclave hosted in the quartz porphyry is 220. 4 +/- 1. 2Ma. The inherited zircons cores that yield Paleoproterozoic and Neoproterozoic ages were found in the monzogranite porphyry. Igneous zircons of Middle-Late Jurassic have low and similar epsilon(Hf)(t) values of -7. 6 similar to -3. 2 and Mesoproterozoic (1. 7 similar to 1. 4Ga) depleted-mantle model ages, which is interpreted to reflect derivation from old crust source. Those old zircons yield positive epsilon(Hf)(t) values of 0. 5 similar to 6. 5 and negative of -1. 5 similar to -0. 07, suggesting involvement of the depleted mantle source in the magma generation. The zircon U-Pb dating and Hf isotope analysis of different kinds of granitoids in ore district imply that they had a cognate origin related to partial melting of ancient continental crust. These data also provide important evidence for temporal-spatial connections of emplacement of the granitiods and W-Sn-Cu-Pb-Zn-Ag polymetallic mineralization in the Huangshaping mining area. In addition, U-Pb ages of the inherited zircon cores indicate that this area has undergone a complex magmatic history, which maybe the crucial reason of the formation of Cu-Pb-Zn-W-Mo-Fe polymetallic deposit.