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引用本文:梁维,郑远川. 藏南吉松铅锌矿成矿时代的厘定:热液绢云母Ar-Ar年龄[J]. 中国地质, 2019, 46(1): 126-139.
LIANG Wei,ZHENG Yuanchuan. Hydrothermal sericite Ar-Ar dating of Jisong Pb-Zn deposit, Southern Tibet[J]. Geology in China, 2019, 46(1): 126-139(in Chinese with English abstract).
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藏南吉松铅锌矿成矿时代的厘定:热液绢云母Ar-Ar年龄
梁维1, 郑远川2
1.中国地质调查局成都地质调查中心, 四川 成都 610081;2.中国地质大学(北京)地球科学与资源学院, 北京 100083
摘要:
吉松脉状铅锌多金属矿位于特提斯喜马拉雅东段中部,是该带内新近发现的铅锌矿床。吉松铅锌矿矿脉产于数条北东向断裂之中,以石英-方解石-硫化物脉形式充填断裂破碎带。本文采用Ar-Ar同位素年代学方法对石英-硫化物脉中的绢云母进行了测试分析,在760~860℃温度区间获得绢云母的坪年龄为(16.61±0.30)Ma,对应的等时线年龄为(16.64±0.30)Ma。两组年龄在误差范围内相等,能够代表绢云母的形成时间。该Ar-Ar年龄指示了吉松铅锌矿形成于17 Ma左右。特提斯喜马拉雅成矿带在主碰撞成矿阶段发育一期金(银)矿化事件(59~49 Ma),而以吉松为代表的铅锌矿化事件则集中于后碰撞阶段(21~12 Ma)。由于吉松铅锌矿与错那洞淡色花岗岩体密切的时空关系,结合二者相似的铅同位素关系,暗示错那洞淡色花岗岩为吉松铅锌成矿提供了物源和热驱动力。
关键词:  特提斯喜马拉雅  吉松  Ar-Ar年龄  藏南  铅锌矿
DOI:10.12029/gc20190108
分类号:
基金项目:科技部国家重点研发计划(2016YFC0600308)、中国地质调查局项目“冈底斯—喜马拉雅铜矿资源基地调查”(DD20160015)和国家自然科学基金项目(41702080)共同资助。
Hydrothermal sericite Ar-Ar dating of Jisong Pb-Zn deposit, Southern Tibet
LIANG Wei1, ZHENG Yuanchuan2
1.Chengdu Institute of Geology and Mineral Resources, China Geological Survey, Chengdu 610081, Sichuan, China;2.School of Earth and Resources, China University of Geosciences, Beijing 100083, China
Abstract:
The Jisong Pb-Zn deposit is one of the newly found deposits in the Tethys Himalaya belt. Orebodies mainly occur as veins in several nearly NE-striking faults. The veins are mainly composed of quartz, calcite, and sulfides. Hydrothermal sericite is genetically associated with zinc and lead mineralization and coexists with quartz, calcite, pyrite, sphalerite and galena. These sericite grains were separated for Ar-Ar isotopes dating. The results yielded a plateau age of (16.61±0.30) Ma at 760-860℃, with the corresponding isochron age being (16.64±0.30) Ma. These two ages are the same within the error, indicating that they can represent the formation age of the Jisong Pb-Zn deposit. Tethys Himalaya developed an Au (Ag) mineralization event in the main collisional orogenic setting, and the Ar-Ar age of the Jisong deposit indicates that Pb-Zn mineralization represented by Jisong in South Tibet occurred at late collisional stage. Combined with close spatial relationships as well as the similarities in time and Pb isotopes between the Jisong deposit and the Cuonadong leucogranite, the authors hold that the leucogranite possibly offered material and heat to the Jisong ore-forming hydrothermal system.
Key words:  Tethyan Himalaya  Jisong  Ar-Ar dating  South Tibet  Pb-Zn deposit