地学前缘 ›› 2010, Vol. 17 ›› Issue (1): 93-.

• 论文 • 上一篇    下一篇


羌塘中部龙木错—双湖缝合带中硬玉石榴石二云母片岩的成因及意义

  

  1. 吉林大学 青藏高原研究中心, 吉林 长春 130061
  • 出版日期:2010-01-28 发布日期:2010-01-28
  • 通讯作者: 董永胜(1968—),男,副教授,从事岩石学研究。Email:dongys@jlu.edu.cn
  • 作者简介:张修政(1985—),男,硕士研究生,变质岩石学专业。Email:zhangxz09@mails.jlu.edu.cn
  • 基金资助:

    国家自然科学基金项目(40872146,40672147);中国地质调查局项目(1212010818015)

Formation and significance of jadeitegarnetmica schist newly discovered in Longmu CoShuanghu suture zone, central Qiangtang.

  1. Research Center For Tibetan Plateau, Jilin University, Changchun  130061, China
  • Online:2010-01-28 Published:2010-01-28

PDF (PC)

878

摘要：

羌塘中部的高压变质带位于龙木错—双湖—澜沧江板块缝合带之上,由榴辉岩、蓝片岩和石榴石白云母片岩组成。其形成过程对探讨板块缝合带的构造演化具有重要意义。2008年笔者在果干加年山地区的展金岩群湖南山岩组中发现了硬玉石榴石二云母片岩这种新的高压变质岩石类型,文中以其为研究对象,做了较为详细的岩石学、矿物学以及变质作用的研究,认为硬玉石榴石二云母片岩至少经历了二期的变质作用:第一期早期绿片岩相,形成了片理S1,其pT条件为T=425～434 ℃,p=300～500 MPa;第二期主期蓝片岩相高压变质作用,形成岩石主期片理S2,其pT条件为T=472～481 ℃,p=1 200～1 700 MPa。硬玉石榴石二云母片岩是榴辉岩折返过程中构造事件的产物,这期折返事件形成了218~220 Ma的一期蓝片岩相变形变质作用。

关键词: 高压变质带, 硬玉, 蓝片岩相, 折返, 羌塘中部

Abstract:

 The highpressure metamorphic belt in central Qiangtang is located in Longmu CoShuanghu suture zone, and composed of eclogite, blue schist and garnet muscovite schist. Its formation process has important significance for the study of tectonic evolution of this suture zone. In 2008, the author found the jadeite garnet twomica schist in the Hunanshan petrofabric, Zhanjin group, which is a new highpressure metamorphic rock type. In this paper, we do a detailed research on petrology, mineralogy and metamorphism of this rock, and consider that this jadeite garnet twomica schist has undergone at least two stages of metamorphism. The first stage was greenschist facies at T=425434 ℃, p=300500 MPa, in which formed the early schistosity S1; the second stage was highpressure metamorphism of blueschist facies at T=472481 ℃, p=12001700 MPa, in which formed the schistosity S2 of main rock period. These rocks were formed in one period of blueschist facies metamorphism and deformation, ranging from 218 Ma to 220 Ma, which was produced by the tectonic movement of the eclogite exhumation.

Key words: high pressure metamorphic belt, jadeite, blueschist facies, exhumation, central Qiangtang