西藏嘎拉勒金铜矿床^(40)Ar/^(39)Ar同位素年龄及地质意义  

Ar-Ar isotopic age of phlogopite from the Galale gold-copper deposit in Tibet and its geological significance

作　　者：张雄[1,2] 杨竹森[2] 何林 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]中国地质科学院矿产资源研究所,北京100037 [3]西藏自治区第二地质大队,西藏拉萨850000

出　　处：《岩石矿物学杂志》2014年第6期1127-1133,共7页Acta Petrologica et Mineralogica

基　　金：国家重点基础研究发展计划(973)项目(2011CB403104);地质调查计划项目(1212010918014);IGCP/SIDA/600资助项目

摘　　要：西藏嘎拉勒矽卡岩型金(铜)矿床为近几年由西藏自治区第二地质大队发现的具有一定规模和潜力的矿床。本文以嘎拉勒金铜矿床中矽卡岩中金云母为研究对象,通过40Ar/39Ar同位素定年的方法,精确厘定了嘎拉勒矽卡岩型金铜矿床的成矿时代。金云母结晶在石榴子石和透辉石、黄铁矿和黄铜矿形成之间,并与石榴子石、针状透闪石和放射状阳起石密切共生。测试结果表明,嘎拉勒矿区金云母的40Ar/39Ar坪年龄为85.41±0.64 Ma,与相应的等时线年龄85.9±2.4 Ma一致,推测其成矿作用可能与拉萨地块和羌塘地块碰撞后在拉萨地块北侧发生岩石圈拆沉引起地幔物质上涌而诱发的岩浆活动有关。The Galale skarn gold （copper） deposit in Tibet discovered by No. 2 Geological Party of Tibet in re- cent years is a deposit of a certain size and potential. In this paper, with the phlogopite from the Galale sham gold-copper deposit as the study object and by using the method of ^40Ar/^39Ar isotopic dating, the authors deter- mined the ore-forming age of the Galale sham gold-copper deposit precisely. Phlogopite crystallized between the formation of garnet and diopside and the formation of pyrite and chalcopyrite, and was closely associated with garnet, tremolite and actinolite. Test results show that the ^40Ar/^39Ar plateau age of phlogopite from the Galale deposit is 85.41± 0.64 Ma, consistent with the corresponding isochron age 85.9± 2,4 Ma. It is thus inferred that mineralization might have been related to the magmatic activities induced by upwelling mantle caused by lithospheric delamination that occurred in the north of Lhasa block after the collision of Lhasa block with Qiang- tang block.

关 键 词：^40AR/^39AR年龄 金云母 矽卡岩 嘎拉勒 西藏 

分 类 号：P597[天文地球—地球化学]