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高黎贡构造带作为藏东三江地区大地构造上的一条重要构造带,在印度-欧亚板块碰撞过程中起着重要的调节作用,并被认为是该地区发生“大陆逃逸”与地块旋转的西边界。本文以高黎贡构造带中的深变质岩为研究对象,通过对高黎贡变质岩带南段进行详细地构造解析,发现其内部广泛发育一系列或顺岩石面理、或切割面理分布的淡色花岗岩脉;并选取了5个淡色花岗岩脉样品进行锆石U-Pb测年,这5个样品的锆石~(206)Pb/~(238)U年龄值主要分布于二个区间:68~40Ma和24~21Ma,并在45Ma左右形成一个巨大的峰值。基于锆石的晶形、晶内结构和微量元素组成特征等方面进行锆石成因学分析,认为本文所测试的5个淡色花岗岩脉样品的锆石为深熔作用过程中形成的锆石;从而推测高黎贡变质岩带南段发生深熔作用并形成淡色花岗岩脉的时代主要集中于68~40Ma和24~21Ma。
The Gaoligong tectonic belt, as an important tectonic belt of the tectonic structure in the Sanjiang area of eastern Tibet, plays an important regulatory role in the Indian-Eurasian plate collision process and is believed to have occurred in the area where “continent escape” and " Block rotating west border. In this paper, taking the deep metamorphic rocks in the Gaoligong tectonic belt as the research object, through the detailed structural analysis of the southern section of the Gaoligong metamorphic rock belt, it is found that there are a series of well-developed rock or bedding distributions Of the pale-grained granite veins. Five pale-grained granite veins were selected for zircon U-Pb dating. The zircon 206 Pb / 238 U age values of the five samples were mainly distributed in two intervals: 68 ~ 40Ma and 24 ~ 21Ma, and around 45Ma to form a huge peak. Based on zircons’ crystal shape, intragranular structure and trace element composition, the zircon eclogites were analyzed, and the zircons of the five samples of pale-colored granite veins tested in this paper are zircons formed during the deep-melt process. The era of deep melting and the formation of pale-grained granite veins in the southern segment of the Gaoligong metamorphic rock belt mainly concentrated in 68-40Ma and 24-21Ma.