Sources of metallogenic materials and metallogenic mechanism of Daliangzi Ore Field in Sichuan Province: Constraints from geochemistry of S, C, H, O, Sr isotope and trace element in sphalerite

The Daliangzi Pb-Zn deposit located on the southwestern margin of the Yangtze Craton, with reserve of 1. 80Mt and averaging grade of 11. 45% ( lead + zinc), is one of the famous high-grade Pb-Zn ore fields in the Sichuan-Yunnan-Guizhou metallogenic belt. Geochemistry of Sr, C, H, O, S isotope and trace element in sphalerite is discussed in this paper in an effort to understand the sources of the ore metals and ore-fluids which cause many different opinions in understanding the genesis of the deposit The results show that the Ge/In and Ga/In of sphalerites with As, Sb and Ag enriched are much bigger than 100 which indicate the metallogenic environment is of mid-low temperature. The origin of a mix of meteoric and metamorphic (formation) water can be inferred after the datum that the delta O-18(H20) values range from -6. 02% similar to 3. 31 parts per thousand and the delta D values range from -74. 6 parts per thousand similar to -40. 3 parts per thousand of the ore-fluids. delta C-13(V-PDB) and delta(18)(O-VSMOW), values of the hydrothermal gangue minerals calcite and dolomite are -3. 5 parts per thousand similar to +1.4 parts per thousand and +11. 6 similar to +18. 1 parts per thousand, indicating that the CO2 in the ore-forming fluid was derived from the dissolution of Sinian carbonates and was greatly affected by the meteoric water and organic carbon in the Ore bearing rock. The most of delta S-34 values of sulfides are 10 parts per thousand 20 parts per thousand, and the delta S-34 values of sulfates are 20. 2% similar to 38. 7 parts per thousand, suggesting that the sulfur should be derived from the in-situ thermochemical reduction of sulfates from the sedimentary strata. The initial Sr-87/Sr-86 values of the ore-forming fluid are 0. 707137 similar to 0. 714588 with the mean value of 0. 711951 which are higher than Sr-87/Sr-86 values (0. 70834 similar to 0. 70861) of the host rock Sinian dolomite and lower than Sr-87/Sr-86 values (0. 7249 similar to 0. 7288) of the basement and some part of the Sinian formation which had high Sr-87/Sr-86 values, implying that the ore-forming fluid probably migrated through the basement and the Sinian formation and experienced water-rock reaction and isotope exchange among the ore fluid, the basement and Sinian formation.