Sulfur and lead isotope composition and tracing for sources of ore-forming materials in the Naruo Cu(Au) deposit, in Tibet

On the basis of detailed field geological survey and mineralogical research, in order to discuss the source of ore-forming materials from the Naruo copper (gold) deposit in the Duolong ore-concentrated area and study the metallogenic mechanism, we analyzed the sulfur and lead isotope from the orebody, discussed the significance. The results show that the δ³⁴S values of the seventeen metal sulfides vary from －2.3‰ to 2.3‰, with an average of 0.13‰. The δ³⁴S values of thirteen pieces of pyrite vary from －2.3‰ to 2.3‰, with an average of 0.17‰. δ³⁴S values of four pieces of chalcopyrite vary from －1.5‰ to 0.8‰, with an average of －1.1‰. The δ³⁴S histogram is distributed approximately in a tower shape, with an average nearly zero, which indicates a mantle source. ²⁰⁸Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb, ²⁰⁶Pb/²⁰⁴Pb isotopic composition of metal sulfides respectively are 38.209~38.854, 15.541~15.665 and 17.942~18.58, with average of 38.635, 15.605 and 18.641. These data show the normal lead characteristics. Lead isotope μ values range from 9.40 to 9.57, less than 9.58. The feature shows that lead mainly comes from mantle material. Sulfur and lead isotopic characteristics of theNaruo deposit are identical with those of other porphyry deposits in the Duolong ore-concentrated area. The ore-forming materials of theNaruo deposit was mainly derived from mantle materials in an island arc environment, and there may be a mix of shell-derived materials.