Sulfur and Lead Isotopic Geochemistry of the Mayuan Pb-Zn deposit in Shanxi Province: Implications for ore-forming material source

摘要

Mayuan Pb-Zn ore deposit is tectonically located in the southeastern margin of the Beiba Arch in the northern of Yangtze Plat. Its orebodies occur in the Upper Sinian Dengying Formation dolomite. Sulfide minerals are selected from the deposit for sulfur and lead isotope compositional analyses. The δ~(34)S values of sulfide minerals vary from 15.5% to 19.6% and the average is 17.67%, indicating that the sulfur was mainly derived from marine sulfate reduction and reduced sulfurs that were probably derived from thermo-chemical sulfate reduction (TSR). The ~(206)Pb/~(204)Pb values vary from 17.62%～18.02% and the range is 0.4%, the ~(207)Pb/~(204)Pb values vary from 15.49～15.65% and the range is 0.16%, and the ~(208)Pb/~(204)Pb values vary from 37.57～38.35%, the range is 0.78%. The uniformity of lead isotope composition displays the same feature as normal lead. The Pb isotope compositions of these sulfide minerals are same to that of the upper crustal lead according to the Zartman diagrams and the Δβ-Δγ diagrams, implying that Pb may come from rocks in the Upper crust. Based on the geochemical characteristics of the sulfur and lead isotope compositions from the Mayuan Pb-Zn deposit, the ore -forming materials may derived from the basement.