广东河台金矿硫化物地球化学特征及地质意义 |
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关键词:pyrite trace elements Sr-Nd isotopes sources of ore-forming fluids and metals Hetai goldfield in Guangdong Province |
基金项目:云南省科技计划项目高层次科技人才及创新团队选拔专项(编号: 202305AT350004);云南省科技计划项目(编号: 202202AG050006);国家自然科学基金项目(编号: 41902086) |
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Geochemical Characteristics and Geological Implications of Sulfides in the Hetai Goldfield, Guangdong Province |
Hetai goldfield, the largest gold-concentration district in Guangdong Province, is a typical example of gold mineralization related to ductile-shear deformation. Deposits in the goldfield occurred in the Yunkai metamorphic series, however, the close spatial and temporal association with the Yunlougang and Wucun granitoids, and the multi-stage mineralization resulted in long-term controversy regarding the source of ore-forming fluids and metals. The Au mineralization in the goldfield predominantly occurs as native gold intimate intergrowth with ore minerals that including pyrite, chalcopyrite, and pyrrhotite. We analyzed the trace elements and Sr-Nd isotopes of pyrite and pyrrhotite that present at the gold-sulfide substage of hydrothermal mineralization stage to further constrain the origin of the ore-forming fluids and metals. Two types of sulfides had Co/Ni ratios in range of 0.36 to 3.33, indicating a mainly hydrothermal genesis. The ratios of Hf/Sm, Nb/La, and Th/La of the sulfides are less than 1, suggesting that ore-forming fluids were enriched in Cl–; Y/Ho ratio of this study varied from 12.0 to 33.0, significantly different from that of mylonite; and (87Sr/86Sr)i and εNd(t) values in the range of 0.707 078 to 0.713 545 and –19.36 to –15.12, respectively, between the HuaXia Plate basement and EM-1 enriched mantle. The above results suggested the multi-origin of the ore-forming fluids. Pyrite with ∑LREE/∑HREE values ranging from 5.53 to 15.4 and obviously negative Eu anomaly with δEu values from 0.48 to 0.75, had remarkable similarity to the mylonite in the chondrite-normalized diagram with right incline pattern, suggesting that the ore-forming metals were mainly derived from the surrounding metamorphic series. Combined with previous geochronological result, we proposed that during the Indosinian period, the metamorphic fluids that derived from the migmatization and ductile shearing drove the ore-forming metals from the Yunkai Group to initially concentrate in the shear zones. In the Yanshanian period, magmatic fluids that derived from the remelting of the Paleo-Proterozoic HuaXia Plate basement mixed with some mantle-derived fluids, playing a role as the carrier and driving force for the activation and migration of ore-forming metals, resulted in the formation of economic orebodies at the favorable place within the shear zones. |
JIAO Qianqian,ZHANG Lu,ZHANG Shengyin,ZHU Pingping,DAI Jiarun,GONG Chaoyang.2024.Geochemical Characteristics and Geological Implications of Sulfides in the Hetai Goldfield, Guangdong Province[J].Acta Geoscientica Sinica,45(4):609-622. |
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