摘要
龙泉关韧性剪切带位于山西、河北两省分水岭两侧的狭长地区内,全长约100km,宽2～14km,总体呈北北东向带状展布。据其变形特征在横、纵向上的明显变化,可分北、中、南三段:北段由眼球状片麻岩、长英质糜棱岩及构造透镜体组成,片麻岩中发育各类旋转碎斑构造,指示上盘(西盘)左旋剪切;中段由强直片麻岩组成,发育平直的片麻理及矿物拉伸线理,为S-L构造岩;南段由一系列线状强变形带及所挟持包绕的弱应变域所组成,变形岩石发育条带状、杆状构造。该剪切带内含有不同时期的变质岩系,主体为中太古代阜平期变质岩系,其构造形迹为一多期多相叠加的韧性剪切带;五台早期表现为伸展型近水平韧性剪切变形,是五台海盆早期扩张或裂解阶段的直观反映;吕梁期韧性剪切变形表现为逆冲推覆型。其形成及构造演化是区内早前寒武纪地质演化的缩影。
Longquanguan ductile shear zone is located in the conjunction part between Shanxi and Hebei Province.It is about 100 km long and 2 ～ 14 km wide. The deformation characters changed obviously both in horizontal and in longitudinal directions. According to the deformation characters the shear zone can be divided into three parts: the northern part, middle part and southern part. In the northern part,the shear zone is made up of augen gneiss, felsic mylonite and structural lenses, and varied kinds of ratational mortar texture developed well, the upper wall shears left-laterally. The main rocks in the middle part are the strong-straight gneisses with mineral stretch lineation, called S-L tectonite. In the southern part, the rocks formed linear strong deformation zones and weak deformation domains. The banding and rodding structure developed well. In the shear zone there are some metamorphic rock series with different eras, in which the Middle-Archean Fuping complex is predominant one. They formed a multiphase-overprint ductile shear zone. During Early Wutai period, its deformation is almost horizontal ductile shearing, which was the reflection of the extension and cracking of Wutai sea-basin. In Lüliang period, the ductile shearing deformation turned to be thrusting nappe structure.
出处
《地质调查与研究》
2004年第2期92-100,共9页
Geological Survey and Research
基金
1:25万忻州市幅区调(20001300004051)
