西藏洞中拉铅锌矿床石英激光探针^(40)Ar-^(39)Ar定年及地质意义  

LASER MICROPROBE ^(40)Ar-^(39)Ar GEOCHRONOLOGY OF QUARTZ FROM DONGZHONGLA LEAD-ZINC DEPOSIT IN TIBET AND ITS SIGNIFICANCE

作　　者：费光春[1] 温春齐[1] 周雄[1,2] 吴鹏宇[1] 温泉[1] 

机构地区：[1]成都理工大学地球科学学院,四川成都610059 [2]中国地质科学院矿产综合利用研究所,四川成都610041

出　　处：《矿物岩石》2010年第3期38-43,共6页Mineralogy and Petrology

基　　金："十一五"国家科技支撑计划(2006BAB01A04);矿物学;岩石学;矿床学国家重点(培育)学科(SZD0407)

摘　　要：洞中拉铅锌矿床是念青唐古拉山地区扎雪-亚贵拉成矿带内新发现的中大型矿床,首次针对矿床中含矿石英脉进行激光探针40Ar/39Ar同位素年代学测定,结果其40Ar/36Ar-39Ar/36Ar等时线年龄为42.2 Ma±1.7 Ma,36Ar/40Ar-39Ar/40Ar等时线年龄为42 Ma±3 Ma(MSWD=2.4n=27),初始值(40Ar/36Ar)0=303.6±1.4。二者年龄具有一致性,可以代表铅锌矿床的形成年龄,形成于始新世早期。同一矿带内沙让钼矿床辉钼矿Re-Os法等时线年龄为51 Ma±1.0 Ma(MSWD=0.55)和52.25 Ma±0.31 Ma(MSWD=0.61),亚贵拉铅锌钼多金属矿床辉钼矿Re-Os同位素平均模式年龄58.7 Ma±8.5Ma,表明念青唐古拉山扎雪-亚贵拉成矿带内存在印-亚大陆主碰撞期(40 Ma^65 Ma)大规模成矿作用,为念青唐古拉地区铅锌铜钼多金属矿产找矿方向研究提供了重要证据。Dongzhongla ore deposit is located in the Zhaxue-Yaguila mineralization area,Nyainqentanglha Range,Tibet and is a new founded middle-large size lead-zinc deposit.The host quartz veins in the Dongzhong lead-zinc deposit was measured by laser microprobe 40Ar-39Ar dating method in order to obtain the ore-forming age.As a result,the isochron age of the ore is 42.2 Ma±1.7 Ma,inverse isochron age is 42 Ma±3 Ma with the MSWD value of 2.4,and the initial 40Ar/36Ar value of 303.6±1.4.The measured age is in agreement with the inverse isochron age within a reasonable error range,and the dating results can be regarded as the ore-forming age of the Dongzhong lead-zinc deposit（formed during early Eocene）.In the same mineralization zone,the Sharang porphyry molybdenum deposit has a Re-Os isochrone age of 51 Ma±1.0 Ma,and the Yaguila lead-zinc-molybdenum polymetallic deposit yields a Re-Os weighted average model age of 58.7 Ma±8.5 Ma.All the geochronology information indicated that the mineralization movements occurred during main Indian-Asian collision period（41 Ma^65 Ma） in the Nyainqentanglha mineralization belt.This study provided important evidence for the research and exploration of lead-zinc molybdenum-copper polymetallic ore deposits in the Nyainqentanglha Range.

关 键 词：成矿时代 激光40Ar-39Ar定年 洞中拉 念青唐古拉 

分 类 号：P597.3[天文地球—地球化学]