西藏嘎拉勒夕卡岩型铜金矿白云母^(40)Ar-^(39)Ar年龄及其地质意义  

^(40)Ar/^(39)Ar age of muscovite from the Galale skarn type copper-gold deposit in Tibet and its geological significance

作　　者：汪傲[1] 赵元艺[2] 许虹[1] 卢伟[1] 郭硕[1] 

机构地区：[1]中国地质大学(北京),北京100083 [2]中国地质科学院矿产资源研究所国土资源部成矿作用与矿产资源评价重点实验室,北京100037

出　　处：《地质通报》2014年第7期1008-1014,共7页Geological Bulletin of China

基　　金：国家"973"课题(编号:2011CB403103);国家科技支撑课题(编号:2006BAB01A05);专题中国地质调查局青藏专项(编号:1212010818097)

摘　　要：西藏嘎拉勒夕卡岩型铜金矿床中铜的资源量达到中型规模,金的资源量达到大型规模。在系统的野外地质调查基础上,选取矿床夕卡岩中保存极好的白云母,测得40Ar-39Ar年龄为91.48Ma±0.68Ma,代表矿床成矿年龄,表明矿床为燕山运动晚期的产物。结合区域地质资料认为,在拉萨地块中北部,成矿年龄约为90Ma的夕卡岩型—斑岩型矿床集中分布在措勤—申扎岩浆弧上;在早白垩世班公湖—怒江洋盆闭合后,狮泉河—永珠—纳木错—嘉黎蛇绿混杂带(Slainajap带)上的弧后盆地和弧间盆地演化成了一系列小洋盆,这些小洋盆的演化与中拉萨地块北部成矿年龄约为90Ma的夕卡岩—斑岩型矿床的形成有更直接的关系。今后宜加大在措勤—申扎岩浆弧上寻找成矿年龄约为90Ma的夕卡岩—斑岩型矿床的力度。Located in Gegya County of Ngari Prefecture, Tibet, and lying in the mid-north Lhasa terrane, the Galale skarn-type copper-gold deposit contains medium-size copper resources and large-size gold resources. Based on a systematic field geological survey,the authors obtained a 91.48Ma±0.68Ma ^40Ar-^39 Ar age of muscovite from skarn in this deposit, which presents its metallogenic age and suggests a late Yanshanian product. Combined with regional geological data, the authors have concluded that skarn-porphyry type deposits in mid-north Lhasa terrane, whose metallogenic age is about 90 Ma, are mainly concentrated in the Coqen-Xainza magmatic arc. After the closure of Bangong-Nujiang Ocean in the Early Cretaceous, these back-arc basins and inter-arc basins, represented now by the Slainajap belt, evolved into some small oceans, and the evolution of these small oceans seemed to be the main factor for the formation of these 90 Ma deposits. The authors hold that more work should be done on the exploration of 90 Ma skarnporphyry type deposits along Coqen-Xainza magmatic arc.

关 键 词：40AR-39AR年龄 夕卡岩—斑岩型矿床 措勤—申扎岩浆弧 拉萨地块中北部 

分 类 号：P578.959[天文地球—矿物学] P597.3[天文地球—地质学]