Advances tn understanding the post-Caledonian structural evolution of the Bergen area, West Norway
Advances tn understanding the post-Caledonian structural evolution of the Bergen area, West Norway
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挪威西部卑尔根地区后加里东时期结构演化的进展
DOI：
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发表时间：
1998
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影响因子：
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通讯作者：
H. Fossen
中科院分区：
文献类型：
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作者：
H. Fossen
而后牛津断层则被识别为没有明确运动学指标的非粘性断层带。对Oygarden、Sotra、Lovstakken和Hjeltefjord地区黏性断岩断层群进行滑动分析，得出相对一致的NW -SE伸展方向。对索特拉西部二叠纪岩脉和森霍德兰二叠系-侏罗系岩脉的详细考察表明，在260 Ma左右，其东向西伸展方向非常精确。这些岩脉沿先前存在的断层和裂缝侵入，大多未变形或节理薄弱。因此，该地区许多脆性或半脆性变形被认为比二叠纪岩脉更古老。这表明，在断裂系统形成和二叠纪岩脉侵入之间的某一时期，最小主应力轴的方向发生了变化。北西向伸展方向与加里东期推覆体早、中泥盆世伸展方向相似，认为卑尔根以西滑动指示发育的主要断裂群反映了泥盆世（晚）应力场。
rocks with striations on slip surfaces, whereas post-Oxfordian faults are identified as non-cohesive gouge zones without clear kinematic indicators. Slip analysis of the fault population with cohesive fault rocks in the Oygarden, Sotra, Lovstakken and Hjeltefjord area gives a relatively consistent NW -SE extension direction. Detailed investigation of Permian dikes in western Sotra and Permo-Jurassic dikes in Sunnhordland indicate a very precise E-W extension direction at about 260 Ma. These dikes intruded along pre-existing faults and fractures, and are mostly undeformed or weakly jointed. M uch of the brittle or semi-brittle deformation in the region is therefore thought to be older than the Permian dikes. This suggests that a change in the orientation of the minimum principal stress axis happened at some time between the formation of the fault systems and intrusion of the Permian dikes. Since the NW extension direction is similar to the early to mid-Devonian stretching direction detected in the Caledonian nappe region, it is suggested that the main population of faults with well-developed slip indicators west of Bergen reflects the (late) Devonian stress field.