商南地区秦岭群中的韧性伸展构造

在秦岭造山带核部秦岭群变质岩系中,发育有自NWW向SEE方向拉伸的深层次韧性伸展构造。表现为具有定的代表伸展运动方向的塑性拉伸线理、不对称顺层韧性剪切褶皱及横向置换面理等。态因后期挤压收缩作用已发生改变。伸展作用发生于加里东期挤压收缩、构造叠置、陆壳增厚之后,与晚加里东—早海西期大量花岗质深成岩体的上隆侵位密切相关,伸展作用方向近平行造山带走向,时代可能为早海西期。

DUCTILE EXTENSIONAL STRUCTURES IN THE QINLING GROUP, SHANGNAN AREAS

The ductile extensional structures moving at a deep level form NWW to SEE were developing in the metamorphic rocks of the Qinling group in the core of the Qinling erogenic belt. It has stable ductile stretching lineations representing the direction of extension, asymmetric intrafolial ductile shear folds, transversal tectono-transpositional foliations and etc. A change of the place of extensional structures had taken place by compression during the late period. The extension occurred after compression, tectonical stack and continental crust thickening during the Caledonian period. It was closely related to the uplift and emplacement of a large number of granitic plutons in the late Caledonian-early Hercynian. Extension is oriented generally subparal-lelly to the strike of the orogehic belt. The age of extension is early Nercynian period.