XIONG Wei1, CHENG Peng-lin2, ZHOU Gao3, HE Zhi-wei4
(1. The 117 Geological Team, Guizhou Bureau of Exploration and Development of Geology and Mineral Resources, Guiyang 550018, China;
2. The 115 Geological Team, Guizhou Bureau of Exploration and Development of Geology and Mineral Resources, Qingzhen 561400, China;
3. The 106 Geological Team, Guizhou Bureau of Exploration and Development of Geology and Mineral Resources, Zunyi 563000, China;
4. Guiyang Mining Investment & Development Corporation. Ltd, Guiyang 550002, China)
Abstract: The NW Guizhou Pb-Zn metallogenic district is an important part of the Sichuan-Yunnan-Guizhou Pb-Zn metallogenic province in the western Yangtze Block, southwest China. In this district, more than 100 Pb-Zn deposits (spots) have been found so far. Base on the previous research achievements, this paper deeply discusses the origin of ore-forming metals. The 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios of ore whole-rock samples range from 18.439 to 18.729 (average 18.563, n=25), 15.681 to 15.887 (average 15.748, n=25) and 38.885 to 39.522 (average 39.112, n=25), respectively; Pyrite samples have 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios ranging from 18.280 to 18.768 (mean 18.571, n=10), 15.677 to 15.920 (mean 15.737, n=10) and 38.609 to 39.144 (mean 38.940, n=10), respectively; The 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios of sphalerite samples range from 18.029 to 18.726 (average 18.448, n=34), 15.505 to 15.825 (average 15.689, n=34) and 38.145 to 39.455 (average 38.772, n=34), respectively; and Galena samples have 206Pb/204Pb rations ranging from 18.062 to 19.900 (mean 18.536, n=83), 207Pb/204Pb ratios ranging from 15.440 to 16.334 (mean 15.717, n=83) and 208Pb/204Pb ratios ranging from 38.004 to 40.695 (mean 39.022, n=83). The Pb isotopic compositions of ore whole-rock samples are similar to those of sulfide mineral samples, suggesting that the Pb isotopes of gangue minerals don’t have obviously effect on that of ore whole-rock and all the Pb isotopes of ore whole-rock and sulfide minerals can trace the origin of ore-forming metals. Compared with the Pb isotopes of ore whole-rock and sulfide mineral samples with those of the crust, mantle and orogenic belt, and Emeishan basalts, ore-hosting sedimentary rocks and basement rocks, the ore whole-rock and sulfide mineral samples have similar Pb isotopic compositions to those of the hosting rocks and basements, suggesting that the ore-forming metals have mixed sources. We propose that the ore-forming metals in northwestern Guizhou Pb-Zn metallogenic district were derived from the strata (basements and hosting rocks) that flowed through by the ore-forming fluids.
Keywords: Pb-Zn deposit; Pb isotope; ore-forming metal; Guizhou Province; metallogenic district
ACTA MINERALOGICA SINICA Vol. 35, No. 4, 2015, Page 425-429
