Geological, rare earth elemental and isotopic constraints on the origin of the Banbanqiao Zn–Pb deposit, southwest China

• Published in: Journal of Asian earth sciences 2015-11, Vol.111, p.100-112
• Main Authors: Li, Bo, Zhou, Jia-Xi, Huang, Zhi-Long, Yan, Zai-Fei, Bao, Guang-Ping, Sun, Hai-Rui
• Format: Article
• Language: English
• Subjects: C–O–S and Pb isotopes; Origin of hydrothermal fluids; REE; Southwest China; The Banbanqiao Zn–Pb deposit; Western Yangtze Block
• ISSN: 1367-9120; 1878-5786
• DOI: 10.1016/j.jseaes.2015.08.007

•C and REE in the hydrothermal fluids were derived from the carbonate host rocks.•O in the ore-forming fluids was derived from a mixed source of mantle-derived O in Emeishan basalts and dissolved O from the carbonate host rocks.•S in the ore-forming solutions was sourced from evaporites by TSR with a limited influence of mantle-derived S.•Pb in the hydrothermal fluids was originated from a mixed source of the basement rocks and the carbonate host rocks.•The Banbanqiao is a typical carbonate-hosted, stratiform, anticline-controlled, epigenetic and high grade SYG-type Zn–Pb deposit. The newly discovered Banbanqiao Zn–Pb deposit in the southeastern part of the Sichuan–Yunnan–Guizhou (SYG) Pb–Zn metallogenic province is located on the western Yangtze Block, southwest China. Ore bodies of the Banbanqiao deposit are stratiform type, host in dolomitic limestone and dolostone of the Lower Carboniferous Dapu Formation and occur within the NNE-trending Banbanqiao anticline. More than 1.5 million tones (Mt) Zn–Pb ores at grades of 0.26–10.32wt.% Pb and 0.81–28.8wt.% Zn have been controlled until now. δ13CPDB and δ18OSMOW values of calcite separates range from −2.8‰ to −0.7‰ (average −1.1‰) and +14.1‰ to +17.0‰ (average +15.5‰), respectively. The δ13CPDB values are similar to those of marine carbonate rocks, but higher than those of mantle and significantly different from those of sedimentary organic matter. However, the δ18OSMOW values are among those of mantle, marine carbonate rocks and sedimentary organic matter. δ34SCDT values of sulfide separates range from +3.2‰ to +9.9‰ (average +6.5‰), unlike mantle-derived sulfur (0±3‰), whilst lower than evaporites (+22‰ to +28‰) within host strata. 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb values of country shale and dolostone whole-rock samples are 18.47, 15.66 and 38.70, and 18.44–18.60, 15.66–15.85 and 38.70–39.14, respectively. Sulfide separates have 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb values ranging from 18.03 to 18.73, 15.65 to 15.78 and 38.15 to 39.14, respectively. These Pb isotopic data indicate a clearly crustal source of Pb in the plot of 207Pb/204Pb vs. 206Pb/204Pb. Total REE (ΣREE) contents of country shale and dolostone whole-rock samples are 2.63ppm and 0.72–86.2ppm with δEu values are 2.79 and 0.34–0.70, respectively. Pyrite, sphalerite, galena and calcite samples have ΣREE contents of 5.3–36.4ppm, 0.29–3.39ppm, 0.52ppm and 22.0–41.1ppm, respectively, and δEu values of 0.64–0.86, 0.94–2.86, 0.32 and 0.2