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Mineralization Styles and Genesis of the Yinkeng Au‐Ag‐Pb‐Zn‐Cu‐Mn Polymetallic Orefield, Southern Jiangxi Province, SE China: Evidence from Geology, Fluid Inclusions, Isotopes and Chronology
Author(s) -
FENG Chengyou,
LI Daxin,
ZENG Zailin,
ZHANG Dequan,
SHE Hongquan
Publication year - 2014
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/1755-6724.12240
Subject(s) - fluid inclusions , geology , mineralization (soil science) , quartz , geochemistry , mineralogy , salinity , ore genesis , sulfide , metallurgy , materials science , oceanography , paleontology , soil science , soil water
The Yinkeng orefield in Yudu County, Jiangxi Province, SE China, is a zone of concentrated Au‐Ag‐Pb‐Zn‐Cu‐Mn polymetallic ores. Based on summing up basic geology and ore geology of the orefield, the polymetallic deposits in the orefield have been divided into seven major substyles according to their occurring positions and control factors. The ore‐forming fluid inclusion styles in the orefield include those of two‐phase fluid, liquid CO 2 ‐bearing three‐phase and daughter mineral‐bearing multi‐phase. The homogenization temperatures range from 382° to 122°C, falling into five clusters of 370° to 390°, 300° to 360°, 230° to 300°, 210° to 290° and 120° to 200°, and the clusters of 300° to 360°, 230° to 300° and 120° to 200° are three major mineralization stages, with fluid salinity peaks from 4.14% to 7.31%, 2.07% to 7.31% and 0.53% to 3.90%, respectively. The ore‐forming fluids are mainly type of NaCl‐H 2 O with medium to high density (0.74–1.02 g/cm 3 ), or CO 2 ‐bearing NaCl‐H 2 O with medium to low density (0.18–0.79 g/cm 3 ). The fluid salinity and density both show a decline tendency with decreasing temperature. According to the measurement and calculation of H‐ and O‐isotopic compositions in the quartz of the quartz‐sulfide veins, δD V‐SMOW of the ore‐forming fluid is from –84‰ to –54‰, and δ 18 O V‐SMOW of that is from 6.75‰ to 9.21‰, indicating a magmatic fluid. The δ 34 S V‐SDT of sulfides in the ores fall into two groups, one is from –4.4‰ to 2.2‰ with average of –1.42‰, and the other from 18.8‰ to 21.6‰ with average of 19.8‰. The S‐isotopic data shows one peak at –4.4‰ to 2.2‰ (meaning –1.42‰) suggesting a simple magmatic sulfur source. The ore Pb‐isotopic ratios are 206 Pb/ 204 Pb from 17.817 to 17.983, 207 Pb/ 204 Pb from 15.470 to 15.620 and 208 Pb/ 204 Pb from 38.072 to 38.481, indicating characteristics of mantle‐derived lead. The data show that the major ore deposits in the orefield have a magmatic‐hydrothermal genesis and that the SHRIMP zircon age of the granodiorite porphyry, closely related to the mineralization, is 151.2±4.2 Ma (MSWD = 1.3), which can represent the formation ages of the ores and intrusion rocks. The study aids understanding of the ore‐forming processes of the major metallic ore deposits in the orefield.