辽南变质核杂岩主拆离断层的波瓦状构造(corrugation)及其成因

Features and mechanism of corrugation structure in the Liaonan (southern Liaoning) metamorphic core complex

基于对辽南变质核杂岩主拆离断层及下伏韧性剪切带的几何学分析以及拆离断层带构造岩的显微构造研究,结合变质核杂岩构造—岩浆活动及其形成过程和力学机制,重点讨论了主拆离断层的波瓦状构造的特点及其形成条件。结果表明:波瓦状构造的发育与下盘晚期阶段花岗质岩体的侵位具有同时性。伸展构造发育初期就位的深成岩体加热和软化了上部地壳,此时岩石力学属性控制的钝角锯齿状断裂构成了波瓦状构造的雏形,晚期阶段花岗质深成侵入岩的不均匀侵位制约了波瓦状构造的发育。

As an asymmetric Cordilleran-style metamorphic core complex, the Liaonan （southern Liaoning） metamorphic core complex had a west-dipping detachment fault, i.e. the Jinzhou fault zone, which lay on a series of sheared rocks formed at different crustal level and was characterized by typical corrugation structure. The geometry and kinematics of the detachment fault and ductile shear zone beneath the fault were discussed in combination of the tectono-magmatic activities and mechanical properties of rocks during exhumation of the metamorphic core complex. The authers suggested that the corrugation structure was affected by the fracture proper- ties of rocks in an extensional setting. Moreover, late kinematic emplacement of granitic plutons played an important role to development of corrugation structure of the Jinzhou detachement fault zone.