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.%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.
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