The Zoujiashan uranium deposit in the Xiangshan ore field is the largest volcanic-related uranium deposit in China. Hematite-and fluorite-type ores are the predominant mineralization styles. Hematitization in the Xiangshan ore field is closely associated with uranium mineralization, mainly oc- curring as hematitized rocks enclosing fluorite-type vein ores developed in pre-ore illitized porphyritic lava. Detailed petrographic and mass balance calculation studies were conducted to evaluate the mech- anisms for uranium precipitation and mass transfer during hematitization. Petrographic observations suggest that in the hematitized rocks, orthoclase is more altered than plagioclase, and quartz dissolu- tion is common, whereas in the illitized rocks, pyrite commonly occurs within the altered biotite grains, and chlorite grains are locally found. Mass balance calculations indicate that Na2O and U were gained, K2O, CaO and SiO2 were lost, whereas Fe2O3-t remained more or less constant during hematitization. These observations suggest that the hydrothermal fluids were Na-and U-rich and Ca-K-poor, and the Fe2+used for hematitization was locally derived, most likely from biotite, pyrite and chlorite in the host rocks. The Fe2+is inferred to have played the role of reductant to precipitate uranium, and calculation indicates that oxidation of Fe2+ provided by host rocks is sufficient to form ores of economic signifi- cance. Consequently, the hematite-type ore is interpreted to be generated by the reaction between oxi- dized ore fluids and reduced components in host rocks. The development of calcite and pyrite in the flu- orite ores suggests that perhaps mixing between the U-rich fluid and another fluid carrying reduced sulfur and carbon may have also contributed to uranium mineralization, in addition to temperature and pressure drop associated with the veining.

Teng Deng;Guoxiang Chi;Xiongjie Zhang;Zenghua Li;Deru Xu;Shengmiao Li;Pengfei Du;Pei Shang;Shaohao Zou;Wanpeng Zhou;Ke Xu;Hai Yan;Ma Wen;Zhengpeng Ding

State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China;Key Laboratory of Uranium Geology,China Geological Survey,Tianjin 300170,China;School of Earth Sciences,East China University of Technology,Nanchang 330013,China;Department of Geology,University of Regina,Regina S4S 0A2,Canada;Engineering Research Center of Nuclear Technology Application,Ministry of Education,East China University of Technology,Nanchang 330013,China;Jiangxi Engineering Laboratory on Radioactive Geoscience and Big Data Technology,East China University of Technology,Nanchang,330013,China;Geological Bureau of Hunan Province,Changsha 410014,China;Geologic Party No.208,China National Nuclear Corporation,Baotou 410014,China

地球科学学刊（英文版）

[1]Teng Deng;Guoxiang Chi;Xiongjie Zhang;Zenghua Li;Deru Xu;Shengmiao Li;Pengfei Du;Pei Shang;Shaohao Zou;Wanpeng Zhou;Ke Xu;Hai Yan;Ma Wen;Zhengpeng Ding-.Mass Transfer during Hematitization and Implications for Uranium Mineralization in the Zoujiashan Deposit, Xiangshan Volcanic Basin)[J].地球科学学刊（英文版）,2022(02):422-434

Hematitization,Zoujiashan,hematitized,illitized,hematitization,Fe2+used,Fe2+is,orite

Mass,Transfer,during,Implications,Uranium,Mineralization,Deposit,Xiangshan,Volcanic,Basin,uranium,deposit,field,largest,volcanic,related,China,Hematite,fluorite,type,ores,are,predominant,mineralization,styles,closely,associated,mainly,curring,rocks,enclosing,developed,porphyritic,lava,Detailed,petrographic,mass,balance,studies,were,conducted,evaluate,mech,anisms,precipitation,transfer,Petrographic,observations,that,orthoclase,more,altered,than,plagioclase,quartz,dissolu,whereas,pyrite,commonly,occurs,within,biotite,grains,chlorite,locally,found,calculations,Na2O,gained,K2O,CaO,SiO2,lost,Fe2O3,remained,less,constant,These,hydrothermal,fluids,rich,poor,was,derived,most,likely,from,host,inferred,have,played,role,reductant,precipitate,indicates,oxidation,provided,by,sufficient,form,economic,signifi,cance,Consequently,hematite,interpreted,generated,reaction,between,dized,reduced,components,development,calcite,suggests,perhaps,mixing,another,carrying,sulfur,carbon,may,also,contributed,addition,temperature,pressure,drop,veining

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