东秦岭燕山期大陆内部挤压俯冲的构造模式及其证据

THE YENSHANIAN INTRACONTINENTAL COMPRESSION-SUBDUCTION IN THE NORTHERN PART OF THE EAST-QINLIN AREA:ITS TECTONIC MODEL AND EVIDENCES

东秦岭北部的地壳变形、岩浆活动、变质作用、沉积作用及地球物理等多方面综合资料证实:这一地区燕山期发育了一个典型的大陆内部挤压俯冲带。它由黑沟-栾川超壳断裂、商丹俯冲-滑脱带和夹于两者之间的一系列呈自北而南逆冲的次级推覆剪切带所组成。A型孪生花岗岩带的发育、白垩纪红盆地的堆积,沿断裂分布的燕山期变质作用和热液活动均为这一切构造运动过程提供了证据。

Detailed geological and geophysical studies on the crustal deformations, magmatisms, sedimentations and crustal structure in the northern part of the East Qinlin area revealed that a typical intracontinental compression-subbuction belt was developed during the Yenshanian era. The belt is composed of the Hegou-Luanchan transcrustal deep fracture zone, shang-Dan deep dccollement-subduction shearing zone, and a group of imbricated overthrust shearing zones distributed between these two belt. The. products of the intracontinental compreesion-subduction include Yenshanian A-type twin granite belts, the cretaceous red molasse formations of intermountain basins, and Yenshainan zonal amphibolite-greenshist facies metaorphisms and hydrothermal activities along the fractures, the model for intrancontinental compression-subbuction of the East Qinlin area might be an important tectonic model for intracontinental mountain-building.