推覆运动与变质作用初探——以昆仑山前的和田地区为例

A preliminary discussion on overthrusting and metamorphism.

位于昆仑山前的和田地区广泛分布以低温绿片岩相为主的浅变质岩，对其原岩的认识尚有不同。综合分析该变质岩所产化石及区域构造运动背景，认为：其原岩是晚泥盆世至晚石炭世早期沉积的砂泥岩地层，应是新构造运动以来喜山期推覆运动造成的区域动力变质岩。据此认为：和田地区不可能是古老的、具继承性质的板块边缘活动带，浅变质岩的原岩与和田坳陷内的巴楚组和卡拉沙依组相当，新构造运动期的挤压变质作用促进其烃源岩的成熟生烃，强烈的挤压变形既为排烃、运移提供了动力条件，推覆运动还使浅变质岩上覆地层中形成各种构造圈闭，有利于该地区形成油气藏。

There are different opinions about the origin of the mother rock of low degree metamorphic rocks dominated by the low temperature green schist, widely distributed in piedmont Hetian region, Xinjiang autonomous region. A comprehensive analysis of the fossil groups of this metamorphic rock and the background of regional tectonics recognized that the mother rock would be sand and mud stones deposited in Late Devonian to early period of Late Carboniferous, it should be the dynamic metamorphic rock originated from a new tectonic movement overthrusting in Himalayan age. It is recognized according to this idea Hetian region cannot be an old, inherited plate boarder active belt, the mother rock of this low degree metamorphic rock corresponds to the Bachu Group and Karasay Group in Hetian depression. Squeeze metamorphism in new tectonic movement promoted the maturation of hydrocarbon source rocks and hydrocarbon generating. Strong squeeze deformation gave dynamic conditions for hydrocarbon expulsion and migration, and overthrusting makes the formation of various types of structural traps in the formations overlying the low degree metamorphic rocks. These are favorable for the formation of oil/gas reservoirs in this region.