青藏高原拉萨地体南部的泥盆纪花岗岩  

Devonian magmatism from the southern Lhasa terrane,Tibetan Plateau

作　　者：董昕[1] 张泽明[1] 耿官升[1] 刘峰[2] 王伟[2] 于飞[2] 

机构地区：[1]中国地质科学院地质研究所,北京100037 [2]中国地质大学(武汉)地球科学学院,武汉430074

出　　处：《岩石学报》2010年第7期2226-2232,共7页Acta Petrologica Sinica

基　　金：中国地质调查局地质调查工作项目(1212010918012);国家自然科学基金项目(40921001;40772049和40972055);中国地质大学地质过程与矿产资源国家重点实验室开放课题(GPMR200907)联合资助

摘　　要：位于青藏高原南部的拉萨地体经历了强烈的中、新生代造山作用,以及最近确定的晚古生代至早中生代的造山作用,而本文第一次报道了拉萨地体南部所经历的中古生代岩浆热事件。所研究的花岗岩分布于拉萨地体南部的加查附近,主要由斜长石、石英、钾长石和少量黑云母组成,经历了不同程度的塑性变形,呈片麻状或眼球状构造。花岗岩中的锆石具有典型的岩浆结晶成因特征,获得了366.7±2.5Ma的谐和年龄。这一成果为拉萨地体的起源、构造归属以及早期构造演化提供了重要信息。Previous investigations have demonstrated that the Lhasa terrane located at South Tibet have experienced the multi-stages of orogenesis during Cenozoic,Mesozoic and Late Paleozoic.However,the present paper firstly reports a Middle Paleozoic magmatic event generated in the southern Lhasa terrane.The studied granite occurs nearby Jiacha County,consists mainly of plagioclase,quartz,K-feldspar and a minor biotite,and shows gneissic or augen structure,indicating variable degrees of ductile deformation.Zircons from granite are typical of magmatic crystallization,and yield a U-Pb concordant age of 366.7±2.5Ma.This result provides an important constraint on the origin,tectonic affinity and early tectonic evolution of the Lhasa terrane.

关 键 词：泥盆纪花岗岩 年代学 构造演化 拉萨地体 青藏高原 

分 类 号：P588.121[天文地球—岩石学]