Cenozoic reactivation of the Great Glen Fault, Scotland: additional evidence and possible causes
Cenozoic reactivation of the Great Glen Fault, Scotland: additional evidence and possible causes
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苏格兰大峡谷断层的新生代重新激活：更多证据和可能的原因
DOI：
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发表时间：
2013
影响因子：
2.7
通讯作者：
A. Zanella
中科院分区：
文献类型：
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作者：
E. Le Breton;P. Cobbold;A. Zanella
大峡谷断层呈北北东-南南西方向横贯苏格兰北部。根据以往的研究，大峡谷断层在加里东造山运动（奥陶纪至早泥盆世）期间发育为左旋走滑断层。然而，它随后在第三纪右侧重新激活。我们讨论后期阶段的更多证据。在 Eathie 和 Shandwick，含化石侏罗纪海相地层中的小褶皱和断层表明沉积后的右旋滑移。在侏罗纪页岩中，我们发现了层理平行的方解石脉（“牛肉”和“锥中锥”），这可能为显着深度的超压发育和有机质成熟提供证据。因此，正如之前的研究人员所指出的，埃西和尚威克的侏罗纪地层在马里湾近海积累得更深，并且在沿着大峡谷断层的右侧位移期间受到新生代折返。从早始新世到晚渐新世（约47-26Ma），沿大西洋东北脊系统的海底差异性扩张产生了沿法罗断裂带的左旋压冲位移，这是苏格兰的隆起和折返时期。我们认为这种差异扩散是大峡谷断层重新激活的原因。事实上，法罗断裂带的左旋滑移与大峡谷断层的右旋重新激活是相容的。
The Great Glen Fault trends NNE–SSW across northern Scotland. According to previous studies, the Great Glen Fault developed as a left-lateral strike-slip fault during the Caledonian Orogeny (Ordovician to Early Devonian). However, it then reactivated right-laterally in the Tertiary. We discuss additional evidence for this later phase. At Eathie and Shandwick, minor folds and faults in fossiliferous Jurassic marine strata indicate post-depositional right-lateral slip. In Jurassic shale, we have found bedding-parallel calcite veins (‘beef’ and ‘cone-in-cone’) that may provide evidence for overpressure development and maturation of organic matter at significant depth. Thus, the Jurassic strata at Eathie and Shandwick accumulated deeper offshore in the Moray Firth and were subject to Cenozoic exhumation during right-lateral displacement along the Great Glen Fault, as suggested by previous researchers. Differential sea-floor spreading along the NE Atlantic ridge system generated left-lateral transpressional displacements along the Faroe Fracture Zone from the Early Eocene to the Late Oligocene (c. 47–26 Ma), a period of uplift and exhumation in Scotland. We suggest that such differential spreading was responsible for reactivation of the Great Glen Fault. Indeed, left-lateral slip along the Faroe Fracture Zone is compatible with right-lateral reactivation of the Great Glen Fault.