Superimposed fabrics due to reversal of shear sense: an example from the Bergen Arc shear zone, western Norway
Superimposed fabrics due to reversal of shear sense: an example from the Bergen Arc shear zone, western Norway
复制标题
由于剪切感反转而导致的叠加织物：来自挪威西部卑尔根弧剪切带的示例
DOI：
10.1016/0191-8141(96)00014-4
复制
发表时间：
1996
期刊：
影响因子：
--
通讯作者：
O. P. Wennberg
中科院分区：
文献类型：
--
作者：
O. P. Wennberg
详细研究了大型韧性剪切带(挪威西部卑尔根弧形剪切带)上缘的剖面。在剪切带内，不对称构造指示右行或自顶向北西向运动，被解释为代表了晚加里东期或后加里东期的伸展构造。剪切带的上盘具有运动学特征，如与弯曲或倾斜的叶理和不对称的斑块有关的剪切带，指示左行或自上而南的运动。它们被解释为与加里东造山运动期间的逆冲作用有关。所研究的剖面显示了后期右旋剪切对左旋构造的渐进式叠加。这首先导致剪切带和弯曲/倾斜面理之间的钝角减小。随后，石英脉中的不对称细脉发生了向后褶皱，剪切带和与之伴生的弯曲/倾斜面理形成了复合解理。当褶皱的石英脉达到紧凑的等斜几何形状时，右旋不对称伸展剪切带在后期发育。
A profile through the upper margin of a large scale ductile shear zone (the Bergen Arc Shear Zone, western Norway) has been studied in detail. Within the shear zone, asymmetric structures indicate dextral or top-to-NW movement, which is interpreted as representing late or post-Caledonian extensional tectonics. The hanging-wall of the shear zone is characterised by kinematic indicators, such as shear bands associated with curved or inclined foliation and asymmetric boudins, indicating sinistral or top-to-SE movements. These are interpreted as related to thrusting during the Caledonian Orogeny. The studied profile shows the progressive overprinting of the sinistral structures by the later dextral shear. This first led to a decrease in the obtuse angle between shear bands and the curved/inclined foliation. Subsequently, backfolding of asymmetric boudins in quartz veins occurred, and a composite cleavage developed from shear bands and associated curved/inclined foliation. Dextral asymmetric extensional shear bands were developed at a later stage when the folded quartz veins had attained tight to isoclinal geometries.