Geological and Sr-Nd-S-Pb isotopic constraints on the genesis of the Baiyinchagan tin polymetallic deposit, southern Great Xing' an Range, China

The Baiyinchagan deposit is a newly discovered large-scale Sn polymetallic deposit in the southern Great Xing'an Range. Geological, geochemical, fluorite and quartz porphyry Sr-Nd and sulfide S-Pb isotopic data are used in this paper to address the relationship between Sn and Ag-Pb-Zn mineralizations of the deposit. Sr-Nd isotopic compositions show that all the quartz porphyry and fluorite samples have similar range of (Sr-87/Sr-86)(i), (Nd-143/Nd-144)(i) and epsilon(Nd) (t) values, indicating that fluorite is associated with quartz porphyry, and its ore-forming fluid is derived from the magma of the quartz porphyry. Sulfur isotopic data demonstrate that Ag-Pb-Zn ores of the No. I area (delta S-34 = -13.9 parts per thousand similar to -4.8 parts per thousand) and Sn ores of the No. III area of the deposit (delta S-34 = -12.5 parts per thousand similar to -5.3 parts per thousand) have similar range of delta S-34 values, and sphalerite (delta S-34 = - 12.4 parts per thousand similar to - 7.3 parts per thousand, mean - 9.2 parts per thousand) and "Zn-F-B aggregates" in quartz porphyry (es = -10. 6%o -9. 0%c, mean -9. 7%c) also have a same range of in-situ es values, suggesting that the magma of quartz porphyry is the main source for sulfur. Pb isotopic data show that the Ag-Pb-Zn ores of the No. I area (Pb-206/Pb-204 = 18.177 similar to 18. 200, (207)pb/Pb-204 = 15.519 similar to 15.531, Pb-208/Pb-204 = 37.985 similar to 38.053) have similar Pb compositions to those of quartz porphyry (Pb-206/Pb-204 = 18.206 similar to 18.235, Pb-207/Pb-204 = 15.529 similar to 15.530, Pb-208/Pb-204 = 38.025 similar to 38.036), indicating that Pb of the Ag-Pb-Zn mineralization was from magma of quartz porphyry. The geological, Sr-Nd and S, Pb isotopic evidence show that the Baiyinchagan Sn mineralization and Ag-Pb-Zn mineralization are genetically related to each other and their ore-forming fluids and materials were derived from the magma of quartz porphyry.