Sulfur and lead isotope composition tracing for the ore-forming material source of Nachatang Pb-Zn deposit in Tibet

The Nachatang deposit, which discovered in recent years with a medium-large prospective scale, is located in the eastern segment of Gangdese-Nyainqêntanglha metallogenic belt in Tibet. The lack of detailed investigation of mineral origin and metallogenic background restricts the further study of genesis of the deposit. Based on the study of the geological characteristics of the deposit, the S and Pb isotopic characteristics of the main metal minerals in skarn ore ( such as sphalerite, galena and pyrrhotite) are analyzed in this paper, and the source of ore-forming materials of the deposit is discussed. The regional metallogenic regularity is summarized by comparing with the regional typical lead-zinc deposits. The results show that the δ³⁴S(‰) value of metal sulfide varies from －1.6‰ to 4.2‰, with an average value of 1.4‰. The frequency histogram has the characteristics of normal distribution and mantle sulfur source. The ²⁰⁶Pb/²⁰⁴Pb value of metal sulfide ranges from 18.548 to 18.792, with an average of 18.691. The ²⁰⁷Pb/²⁰⁴Pb values range from 15.683 to 15.856, with an average of 15.755. ²⁰⁸Pb/²⁰⁴Pb values range from 39.049 to 39.685, with an average of 39.331. The characteristic μ values of Pb isotope range from 9.61 to 9.93, with an average value of 9.74. The μ values of all samples are higher than 9.58, indicating that the lead source has the characteristics of upper crustal source. Based on the comparative study of regional mineralization, it is concluded that the S and Pb isotope characteristics of the Nachatang deposit are similar to those of the typical skarn Pb-Zn deposits in the eastern segment of Nyainqêntanglha lead-zinc metallogenic belt, and the ore-forming materials are mainly derived from the remelting of crystalline basement materials of the Nyainqêntanglha Group.