JIN Shao-rong1, WANG Yu-chao2, YANG De-zhi1, DAI De-rong1, XU Yang-dong1, ZHOU Jia-xi2,3*
(1. Institute of Geophysical and Geochemical Prospecting, Bureau of Geology and Mineral Exploration and Development of Guizhou Province, Guiyang 550018, China;
2. School of Resource Environment and Earth Science, Yunnan University, Kunming 650500, China;
3. Stake Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China)
Abstract: The southwestern Guizhou is one of the relatively concentrated areas of fluorite resources in Guizhou Province. At present, many fluorite deposits (occurrences) have been found in this region. They are mainly classified into two types, including independent and associated fluorite deposits. The associated fluorite deposits are related to the low temperature Au and Sb deposits which are important components of the large-scale low-temperature metallogenic domain in South China. Until now, the weakness of researches on independent fluorite deposits has seriously restricted the understanding of ore genesis of this scarce strategic non-metallic mineral resource. The Gaoling fluorite deposit is a newly discovered independent one with associated minor Sb mineralization in the periphery of Qinglong Sb deposit. It is an ideal object for studying the ore genesis of independent fluorite deposit. Based on the detailed study of its deposit geology, the fluorite particle micro-drilling sampling technique and fluorite microwave digestion method were used to deal with fluorite samples for analyzing Pb and Sr isotopes by using the high-precision MC-ICPMS. The results show that the Pb isotopic ratios of fluorite are changed in relatively large ranges varying from 18.5107 to 20.1915 for 206Pb/204Pb, from 15.7075 to 15.8298 for 207Pb/204Pb, and from 36.6625 to 38.6938 for 208Pb/204Pb, respectively. The fluorites contain obviously enriched radiogenic Pb, suggesting that the source was rich in radiogenic Pb or the ore-forming fluids flowed through the radiogenic Pb-rich source region. However, the Sr isotopic ratios (87Sr/86Sr) of fluorites vary in a narrow range from0.707845 to 0.707968, which is slightly higher than those of the ore-bearing limestone of Permian Maokou Formation (87Sr/86Sr =0.70679-0.70682), the Emeishan basalts (87Sr/86Sr =0.70480-0.70647), and the Permian seawater (87Sr/86Sr =0.70684-0.70820), indicating that the ore-forming fluids are relatively enriched in the radiogenic Sr. Furthermore, this suggests that the enriched radiogenic Sr could be brought by the ore-forming materials/fluids derived directly from the radiogenic Sr-rich source or obtained through interaction of the passing fluids and radiogenic Sr-rich geological body on the way of uplifting process. On the basis of comparison, this paper considers that the ore-forming materials/fluid of the Gaoling fluorite deposit have multi-source characteristics. The Gaoling deposit belongs to a same metallogenic system of the Qinglong Sb deposit and is a late-stage product of the large-scale low-temperature mineralization.
Keywords: Fluorite; Pb and Sr isotopes; source of ore-forming material/fluids; the Gaoling fluorite deposit
ACTA MINERALOGICA SINICA Vol. 39, No.3, 2019, page 247-252
