东喜马拉雅构造结高压麻粒岩特征、形成机制及折返过程

Genetic mechanisms and exhumation processes of the high-pressure (granulites) within the Eastern Himalayan syntaxis, Xizang

东喜马拉雅构造结一带断续分布的直白高压麻粒岩,是一套相当于下地壳根带深度形成的高压麻粒岩相岩石。该麻粒岩相地体归属印度大陆东北端,是世界上最年轻的麻粒岩相岩石之一,其变质作用与印度大陆与欧亚大陆之间碰撞过程中发生的陆内俯冲作用有关。对于高压麻粒岩的形成机制及折返过程一直是人们研究和观注的焦点。本文在1∶25万墨脱幅区域地质调查项目的研究结果的基础上,依据高压麻粒岩相岩石出露的大地构造背景,讨论了与之有关的若干问题,并提出适合该区的高压麻粒岩的形成机制和折返过程的新认识。

The Zhibai Formation Complex high2ressure granulites within the Eastern Himalayan syntaxis are a succession of high-pressure granulites as the youngest granulites in the world formed at the lower crustal root zones. Tectonically these granulites are assigned to the northeastern part of the Indian continent in a tectonically thickening setting and their metamorphism may be related to the intracontinental subduction during the collision between the Indian and Eurasian continents. The exhumation mechanisms of the granulites may be owed to the rapid uplifting of the Higher Himalayan crystalline rock series caused by large-scale detachment and normal faulting due to the combination of the upper flotational and lower gravitational processes.