五台山早前寒武纪碰撞造山带中的韧性剪切带及其大地构造意义

在五台山早前寒武纪碰撞造山带中存在两种类型韧性剪切带，即逆冲型和伸展型剪切带。除变质程度不同外，南部和北部构造片体中的角闪岩相逆冲型韧性剪切带与中部构造片体中的绿片岩相逆冲型韧性剪切带具有相同的变形特征，它们形成于同一变形过程中，是造山作用早期地壳拼合阶段的产物。伸展型韧性剪切带在整个造山带都有分布，与造山作用晚期显著增厚的地壳发生大规模纵向伸展作用相联系

DUCTILE SHEAR ZONES OF THE PRECAMBRIAN COLLISION OROGENIC BELT IN WUTAISHAN AREA AND ITS TECTONIC SIGNIFICANCE

There are two types of ductile shear zones (DSZs) in late Archaean collision orogenic belt: reversal DSZs and extensional DSZs. A series of reversal DSZs formed in different levels are well developed in three tectonic slices of the orogenic belt and along their boundaries, thrusting imbricatedly southeastward. Except their metamorphic degrees, the reversal DSZs of amphibolite facies in south and north slices are identical to the reversal DSZs of greenschist facies in central slice (e.g. similar occurrences of schistosity, identical direction of thrusting, similar pTt paths and transforms of mineral assemblages, etc.) It is easily acceptable that the reversal DSZs were formed at different levels during the identical evolution of the same deformation, which is related to the thickening of the crust, caused by the subduction during the early stage collision. Extensional DSZs occur in all orogenic belt, they are formed during post collision evolution, related to the thinning of the crust. The remarkable thickening crust of the orogenic belt presented large scale longitudinal extension, which made the crust develop balancedly.