Brittle–ductile deformation in the Glarus thrust Lochseiten (LK) calc‐mylonite
Brittle–ductile deformation in the Glarus thrust Lochseiten (LK) calc‐mylonite
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格拉鲁斯逆冲断层 Lochsiten (LK) 钙糜岩中的脆性-韧性变形
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
M. Burkhard
中科院分区：
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作者：
Nicolas P. Badertscher;M. Burkhard
Glarus逆冲断层容纳了至少30 km的向北位移，强烈地局限于1 m的“Lochseiten”（LK）钙糜棱岩层内。 这一层显示了处于各种塑性变形状态的矿脉和一种严重重折叠的叶理状凿痕结构。在细晶粒再结晶基体中观察到晶格和形状优选取向。这些特征反映了脆性变形机制和韧性变形机制的交替活动。与晶界滑动（超塑性）是主要变形机制的经典观点相反，主张来自下盘并沿逆冲断层沿着排出的流体是水力压裂和碎裂变形的原因。在断裂事件之间的时期，变形是韧性的。在这种新的解释中，总逆冲位移的相当大一部分是由Verrucano逆冲岩席底部的许多短暂和强烈局部化的断裂事件所容纳的，而不是永久性的弱滑脱岩性。
The Glarus thrust accommodated at least 30 km of northward displacement strongly localized within a 1‐m layer of ‘Lochseiten’ (LK) calc‐mylonite. This layer displays veins in various states of plastic deformation and a wildly refolded foliated gouge texture. Lattice‐ and shape‐preferred orientations are observed within the fine‐grained, recrystallized matrix. These features indicate the alternate activity of brittle and ductile deformation mechanisms. In contrast to the classical view that grain boundary sliding (superplasticity) is the dominant deformation mechanism, it is advocated that fluids, derived from the footwall and expelled along the thrust, are responsible for hydrofracturing and cataclastic deformation. In periods between fracture events, deformation was ductile. In this new interpretation, a substantial amount of the total thrust displacement was accommodated by numerous short‐lived and strongly localized fracture events at the base of the Verrucano thrust sheet, rather than a permanently weak décollement lithology.