Origin of the Yueguang gold deposit in Xinhua, Hunan Province, South China: insights from fl uid inclusion and hydrogen–oxygen stable isotope analysisOAEI
The Yueguang gold deposit is located in Fengjia,Xinhua County,Hunan Province,South China.It represents a recently discovered small-scale gold deposit situated in the southwestern region of the Jiangnan Orogenic Belt,west of the Baimashan granitic batholith.In order to discern the characteristics of the ore-formingfluids,the underlying mineralization processes,and establish a foundation for the origin of the Yueguang gold depositfluid inclusion micro-thermometry,as well as quartz hydrogen and oxygen isotope analysis,have been carried out on samples obtained from various stages of mineralization.The hydrothermal miner-alization stages within the Yueguang gold deposit can be categorized into three stages:(i)the barren,pre-ore quartz-pyrite stage(Stage Ⅰ),the quartz-pyrite-gold stage(Stage Ⅱ),and the post-ore quartz-carbonate stage(Stage Ⅲ),with the second stage being the main mineralization stage.Thefluid inclusions identified in samples from the main min-eralization stage can predominantly be described with the NaCl–H_(2)O and CO_(2)–NaCl–H_(2)O systems.These inclusions display homogenization temperatures ranging from 158.8 to 334.9℃,and thefluid salinity ranges from 0.3%to 4.0%(wt.%NaCl equiv.).Laser Raman spectroscopy analysis of individual inclusions further reveals the presence of gas-phases such as CO_(2),CH_(4),and N_(2).Isotopic analysis indicatesδ^(18)Ofluid values ranging from 3.95 to 6.7‰ and δDH_(2)O values ranging from-71.9 to-55.7‰.These results indi-cate that the ore-formingfluid of the Yueguang gold deposit belongs to metamorphic hydrothermalfluids of middle-low temperature and low salinity.In the process of ore formation,gold is transported in the form of Au(HS)2-complexes,with gold deposition being driven byfluid immiscibility.Therefore,the Yueguang gold deposit is categorized as an orogenic gold deposit dominated by metamorphic hydrother-malfluid.It may become a new target for gold exploration in the Baimashan region,central Hunan Province.
Hongxin Fan;Qiang Wang;Yulong Yang;Yao Tang;Hao Zou;
College of Earth Sciences,Chengdu University of Technology,Chengdu 610059,ChinaCollege of Earth Sciences,Jilin University,Jilin 130061,China
地质学
Hunan provinceYueguang gold depositFluid inclusionsHydrogen–oxygen isotopesLaser RamanFluid immiscibilityOrogenic gold deposit
《Acta Geochimica》 2024 (002)
P.235-254 / 20
support from several sources,including the Backbone Teacher Training Program(10912-SJGG2021-04233);the Teaching Reform Project of Chengdu University of Technology(JG2130131);the University-Industry Collaborative Education Project,Ministry of Education,China(22097130210756);National Natural Science Foundation of China(42272129).
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