西藏纳如松多隐爆角砾岩型铅锌矿床绢云母Ar-Ar定年及其地质意义  

The Ar-Ar Geochronology of Sericite from the Cryptoexplosive Breccia Type Pb-Zn Deposit in Narusongduo,Tibet and its Geological Significance

作　　者：纪现华 孟祥金[2] 杨竹森[2] 张乾[3] 田世洪[2] 李振清[2] 刘英超[4] 于玉帅 

机构地区：[1]河北地质调查院,河北石家庄050081 [2]中国地质科学院矿产资源研究所,北京100037 [3]河海大学,江苏南京210009 [4]中国地质科学院地质研究所,北京100037 [5]武汉地质矿产研究所,湖北武汉430205

出　　处：《地质与勘探》2014年第2期281-290,共10页Geology and Exploration

基　　金：国家重点基础研究发展计划(973)项目(2011CB403104);"十一五"国家科技支撑计划项目(2006BAB01A04);地质调查计划项目(1212010918014)资助

摘　　要：纳如松多铅锌矿床位于拉萨地块中部隆格尔-工布江达断隆带中段,为冈底斯铜矿带北侧铅锌银多金属成矿带的典型矿床之一。纳如松多铅锌矿床以发育隐爆角砾岩型和矽卡岩型铅锌矿化为特征。利用40Ar-39Ar同位素测年方法对纳如松多东矿段隐爆角砾岩型主矿体成矿阶段形成的绢云母进行了年龄测定,获得绢云母Ar-Ar坪年龄为(57.81±0.66)Ma,对应的正、反等时线年龄分别为(57.90±1.70)Ma、(57.70±0.77)Ma。所测坪年龄与正反等时线年龄具有很好的一致性,可以代表隐爆角砾岩型铅锌矿体的形成年龄。结合区域地质构造背景,纳如松多隐爆角砾岩型铅锌矿床形成于印度-亚洲大陆主碰撞时期。The Narusongduo Pb-Zn deposit,located in the Longgeer-Gongbujiangda fault-block uplift belt in the center of Lhasa Terrane,Tibet,is one of the representative ore deposits in the Pb-Zn-Ag polymentallic ore belt in the northern side of the Gandese copper ore zone. This deposit is characterized by two types of mineralization,namely cryptoexplosive breccia type in the eastern part and skarn type in the western part. Sericite from the Pb-Zn main orebody of the cryptoexplosive breccia type in Narusongduo was measured by40Ar-39Ar dating. The results show the40Ar-39Ar plateau age of57. 81 ± 0. 66Ma,while the isochronal age of 57. 90 ± 1. 70Ma and the inverse isochronal age of 57. 70 ± 0. 77Ma. The40Ar-39Ar plateau age is in agreement with the isochronal age and the inverse isochronal age within a reasonable error range,which can be regarded as the ore-forming age of the cryptoexplosive breccia type Pb-Zn orebody. Considering the regional geological background,this study suggests that the cryptoexplosive breccia type Pb-Zn deposit in Narusongduo formed during the main Indian-Asian collisional period.

关 键 词：40Ar-39Ar同位素定年 绢云母 隐爆角砾岩 纳如松多铅锌矿体 西藏 

分 类 号：P618.4[天文地球—矿床学]