ZHENG Rong-hua1, GAO Jian-guo2, NIAN Hong-liang1, JIA Fu-ju2
(1. No.317 Geological Part, Yunnan Nonferrous Metals Geological Bureau, Qujing 655000, China;
2. Department of Land Resource Engineering, Kunming University of Science and Technology, Kunming 650093, China)
Abstract: Maozu Pb-Zn deposit is located in the Sinian Dengying Formation dolomite, in the northeast of Yunnan Province, China. Its ore bodies show bedded, vein and irregular shapes. Ores are composed of sphalerite, galena, pyrite and calcite. Through analysis by using TIMS, the Rb-Sr isotopic compositions of five sphalerite separates samples were acquired. Results show that Rb and Sr contents of sphalerite are low, with ranges of 0.05×10-6 to 0.18×10-6 and 0.33×10-6 to 10.02×10-6, respectively. The 87Rb/86Sr values are between 0.052 and 0.850. The 87Sr/86Sr values range from 0.7117 to 0.7210. Although the sphalerite samples do not yield ideal Rb-Sr isochron age, the 87Sr/86Sr values can trace the sources of ore-forming fluids/metals after age-corrected (200 Ma). Compared with the initial 87Sr/86Sr values of ore-hosting Dengying Formation dolostone, Cambrian to Permian sedimentary, Emeishan flood basalts and Proterozoic basement rocks (Kunyang and Huili Groups), the 87Sr/86Sr (0.7106 to 0.7186) values of sphalerite separates from Maozu Deposit are higher than all the related geological bodies except basement rocks. Therefore, we suggest that the ore-forming fluids/metals may be derived from or flowed through the Proterozoic basement rocks, and than mixed with the fluids that derived from or flowed through the covering rocks. The mixed fluids mineralization is an important metallogenic mechanism for Maozu deposit, so the study of fluid migration way has an important theoretical guiding significance for finding new ore bodies.
Keywords: sphalerite; Rb-Sr isotopic composition; ore-forming fluids/metals; Maozu Pb-Zn ore deposit
Email: gaojg_kmust@163.com
ACTA MINERALOGICA SINICA Vol. 35, No. 4, 2015, Page 435-438
