Genesis of the Jiajika superlarge lithium deposit,Sichuan,China:constraints from He–Ar–H–O isotopes  

作　　者：Tao Liu Hai Wang Shihong Tian Denghong Wang Xianfang Li Xiaofang Fu Xuefeng Hao Yujie Zhang Kejun Hou 

机构地区：[1]State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China [2]Changsha Uranium Geology Research Institute,CNNC,Changsha 410007,China [3]Hunan Engineering Technology Research Center for Evaluation and Comprehensive Utilization of Associated Radioactive Mineral Resources,Changsha 410007,China [4]MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China [5]Geological Survey of Sichuan Province,Chengdu 610081,China [6]School of Earth Science and Mineral Resources,China University of Geosciences,Beijing 10083,China

出　　处：《Acta Geochimica》2023年第3期517-534,共18页地球化学学报（英文）

基　　金：financially supported by grants from the National Key Research and Development Project of China(2021YFC2901903 and 2017YFC0602705);the Jiangxi Province(2020101003);the East China University of Technology(1410000874)。

摘　　要：The Jiajika granitic-and pegmatite-type lithium deposit,which is in the Songpan-Garze Orogenic Belt in western Sichuan Province,China,is the largest in Asia.Previous studies have examined the geochemistry and mineralogy of pegmatites and their parental source rocks to determine the genesis of the deposit.However,the evolution of magmatic-hydrothermal fluids has received limited attention.We analyzed He–Ar–H–O isotopes to decipher the ore-fluid nature and identify the contribution of fluids to mineralization in the late stage of crystallization differentiation.In the Jiajika ore field,two-mica granites,pegmatites(including common pegmatites and spodumene pegmatites),metasandstones,and schists are the dominant rock types exposed.Common pegmatites derived from early differentiation of the two-mica granitic magmas before they evolved into spodumene pegmatites during the late stage of the magmatic evolution.Common pegmatites have~3He/~4He ratios that vary from 0.18 to 4.68 Ra(mean1.62 Ra),and their~(40)Ar/~(36)Ar ratios range from 426.70 to 1408.06(mean 761.81);spodumene pegmatites have~3He/~4He ratios that vary from 0.18 to 2.66 Ra(mean 0.87Ra)and their~(40)Ar/~(36)Ar ratios range from 402.13 to 1907.34(mean 801.65).These data indicate that the hydrothermal fluids were shown a mixture of crust-and mantle-derived materials,and the proportion of crustderived materials in spodumene pegmatites increases significantly in the late stage of the magmatic evolution.Theδ~(18)OH_(2)O–VSMOWvalues of common pegmatites range from 6.2‰to 10.9‰,with a mean value of 8.6‰,andδDV–SMOWvalues vary from-110‰to-72‰,with a mean o f-85‰.Theδ~(18)OH_(2)O–VSMOWvalues of spodumene pegmatites range from 5.3‰to 13.2‰,with a mean of 9.1‰,andδDV–SMOWvalues vary from-115‰to-77‰,with a mean of-91‰.These data suggest that the ore-forming fluids came from primary magmatic water gradually mixing with more meteoric water in the late stage of the magmatic evolution.Based on the He–Ar–H–O and other existing d

关 键 词：He–Ar–H–O isotopes Magmatic-hydrothermal fluids Common pegmatites Spodumene pegmatites Jiajika superlarge lithium deposit SICHUAN 

分 类 号：P618.71[天文地球—矿床学] P597[天文地球—地质学]