Affiliation:
1. Faculty of Land Resources Engineering, Kunming University of Science and Technology, Kunming 650093, China
2. Southwest Institute of Geological Survey, Geological Survey Center for Non-ferrous Metals Resources, Kunming University of Science and Technology, Kunming 650093, China
3. City College, Kunming University of Science and Technology, Kunming 650093, China
Abstract
The Dahai Pb-Zn mining area is located in the northwestern Pb-Zn district in northeastern Yunnan Province in the Sichuan-Yunnan-Guizhou Pb-Zn metallogenic triangle (SYGT), east of the Xiaojiang fault. Numerous Pb-Zn deposits (spots) occur in clastic rocks in this area. In this study, the Maliping, Laoyingqing, and Jinniuchang Pb-Zn deposits, representative clastic rocks in the Dahai mining area, were selected as research objects. The results of H-O-S-Sr-Pb isotope analyses show that the three deposits mainly formed through the mixing of a basinal brine with a hydrothermal fluid derived from deep within the underlying (deformed) basement, and brines leached organic matter from wall rocks. The δ34S values range from −2.62–30.30‰. The S isotope results show two different sources of reduced S: one in the Laoyingqing deposit derived from the S reduction generated by the pyrolysis of sulfur-bearing organic matter in the carbonaceous slate of the Kunyang Group, and the second in the Maliping and Jinniuchang deposits derived from the S reduction generated by the thermochemical sulfur reduction (TSR) of seawater sulfate in the Lower Cambrian Yuhucun Formation and Sinian Dengying Formation. The Pb isotope results show that the Pb sources of the three deposits are derived from basement rocks (Kunyang Group) with a small portion derived from Devonian–Permian carbonate rocks and Dengying Formation dolomite, both of which have undergone homogenization during mineralization. The Sr content varied from 0.09629 to 0.2523 × 10−6, and the study shows that the main source of Sr is a mixture of ore-forming fluid flowing through basement rocks (Kunyang Group) and through sedimentary cover. However, most of the Sr in the Maliping deposit is derived from marine carbonate, and in the Laoyingqing deposit, it is provided by basement rocks (Kunyang Group). Based on a comparative study of the deposits, the Pb-Zn deposits in the clastic rocks of the Dahai mining area and the SYGT belong to the same metallogenic system and were formed under the same metallogenic geological background. Finally, a unified metallogenic model of the two types of fluid migration and mixed mineralization of the Pb-Zn deposit in clastic rocks of the Dahai mining area is proposed. The metallogenic model provides a basis for the study of the Pb-Zn metallogenic system and guidance for deep and peripheral prospecting in this area.
Funder
National Natural Science Foundation of China
Yunnan Major Scientific and Technological Projects
Fund of China Yunling Scholars
Fund of Mineral Resources Prediction and Evaluation Engineering Laboratory of Yunnan Province in China
Fund of Innovation Team of Yunnan Province in China
Subject
Geology,Geotechnical Engineering and Engineering Geology
Reference89 articles.
1. Mineralisation model of rich Ge-Ag bearing Zn-Pb polymetallic deposit concentrated district in northeastern Yunnan, China;Han;Acta Geol. Sin.,2012
2. Liu, H.C., and Lin, W.D. (1999). Regularity Research of Pb-Zn-Ag Ore Deposits Northeastern Yunnan, Yunnan University Press. (In Chinese).
3. A discussion on the sedimentary origin of Pb-Zn deposits in western Guizhou and northeastern Yunnan;Chen;J. Guizhou Geol.,1984
4. The source of metalsin the Qilinchang Zn-Pb deposit, Northeastern Yunnan, China: Pb-Sr isotope constrains;Zhou;Econ. Geol.,2001
5. Geodynamic setting of mineralization of Mississippi Valley-type deposits in world-class Sichuan-Yunnan-Guizhou Zn-Pb triangle, southwest China: Implications from age-dating studies in the past decade and the Sm-Nd age of Jinshachang deposit;Zhang;J. Asian Earth Sci.,2014