The northern Bergen Are Shear Zone an oblique-lateral ramp In the Devonian extensional detachment system of western Norway
The northern Bergen Are Shear Zone an oblique-lateral ramp In the Devonian extensional detachment system of western Norway
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卑尔根北部剪切带是挪威西部泥盆纪伸展拆离系中的斜侧坡道
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发表时间：
2012
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通讯作者：
Inger Winsvold
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作者：
O. P. Wennberg;A. Milnes;Inger Winsvold
在卑尔根地区（挪威西部）的北方，对主要的、厚度为2-3 km的、加里东晚期/后伸展的卑尔根弧剪切带进行了构造调查。该剪切带呈陡西南倾，走向由北东115-120°向西南150-160°变化，长度约50 km。下盘由原地西部片麻岩杂岩和最下部加里东推覆体组成。上盘由构造上较高的加里东推覆体不均匀地覆盖在早泥盆世砾岩之上。剪切带内糜棱岩面理的取向，除了几种剪切方向指示因子外，主要是右旋剪切分量。相关的拉伸线理走向约为20° W-NW，反映了区域地质特征的正滑分量。卑尔根剪切带的最小位移量约为16 km，正常倾向滑动分量约为8 km，右旋走滑分量约为14 km。卑尔根弧剪切带在其范围内晚于所有加里东期的逆冲变形。我们认为，卑尔根Are剪切带代表了泥盆纪主要构造北峡湾-松恩构造带的一个分支，发育为斜侧向斜坡。
Structural investigations in the northern part of the Bergen area (western Norway) have been earried out on the major, 2-3 km-thiek, late/post-Caledonian, extensional Bergen Are Shear Zone. This shear zone dips steeply SW with a ehange in strike from 115-120° in the northeast to 150-160° in the southwest, over a distance of 50 km. The footwall eonsists of the autochthonous Western Gneiss Complex and the lowermost Caledonian Nappes. The hanging wall eonsists of strueturally higher Caledonian Nappes uneonformably overlain by eoarse Devonian eonglomerates. The orientation of the mylonitic foliation within the shear zone, in addition to several types of shear-sense indieators, predominantly indieate a dextral shear component. The related stretehing lineation pl unges about 20° W to NW, implying a significant eomponent of normal slip, as indieated by the regional geology. The minimum displacement on the Bergen Are Shear Zone is approximately 16 km, with a normal dip slip eomponent of 8 km, and a dextral strike slip eomponent of 14 km. The Bergen Are Shear Zone post-dates all Caledonian eontraetional deformation in its vieinity. We suggest that the Bergen Are Shear Zone represents a braneh of the Nordfjord-Sogn Detaehment Zone, the main Devonian detaehment, developed as an oblique-lateral ramp.