Fault architecture and deformation mechanisms in exhumed analogues of seismogenic carbonate-bearing thrusts.
Fault architecture and deformation mechanisms in exhumed analogues of seismogenic carbonate-bearing thrusts.
复制标题
挖掘出的类似发震碳酸盐岩逆冲断层的断层结构和变形机制。
DOI：
10.1016/j.jsg.2013.07.007
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发表时间：
2013
影响因子：
3.1
通讯作者：
M. Barchi
中科院分区：
文献类型：
--
作者：
T. Tesei;C. Collettini;C. Viti;M. Barchi
碳酸盐断层是全世界众所周知的上地壳地震活动源。在北亚平宁山脉的外段，古老的碳酸盐岩逆冲断层暴露在地表，与在深处产生地震活动的结构类似。我们描述了从公里尺度到微观尺度的三种大位移推力的几何形状、内部结构和变形机制。断层结构和变形机制都受到断层岩石岩性的影响。在逆冲断层切过层状或泥灰岩的地方，断层带很厚（数十米），并显示出以强烈的压溶变形为特征的叶状岩石（S-CC'构造岩和/或YPR碎裂岩）。在块状石灰岩中，断层发生在局部狭窄区域，表现出丰富的脆性变形。提出并讨论了非均质含碳酸盐逆冲断层的通用模型。断层结构受地层非均质性和继承构造的影响，影响几何粗糙体的位置和断层应变率。粘土矿物的存在和断层岩所经历的应变率调节着从碎裂作用主导的变形向压力溶液主导的变形的转变。由此产生的这些断层的结构异质性可能反映了它们的力学和地震行为：我们认为，地震粗糙体位于局部滑动狭窄区域中的块状石灰岩的边界处，而弱剪切带构成了断层的缓慢滑动部分，反映了其他类型的“地震”行为。
Faults in carbonates are well known sources of upper crustal seismicity throughout the world. In the outer sector of the Northern Apennines, ancient carbonate-bearing thrusts are exposed at the surface and represent analogues of structures generating seismicity at depth. We describe the geometry, internal structure and deformation mechanisms of three large-displacement thrusts from the km scale to the microscale. Fault architecture and deformation mechanisms are all influenced by the lithology of faulted rocks. Where thrusts cut across bedded or marly limestones, fault zones are thick (tens of metres) and display foliated rocks (S-CC′ tectonites and/or YPR cataclasites) characterized by intense pressure-solution deformation. In massive limestones, faulting occurs in localized, narrow zones that exhibit abundant brittle deformation. A general model for a heterogeneous, carbonate-bearing thrust is proposed and discussed. Fault structure, affected by stratigraphic heterogeneity and inherited structures, influences the location of geometrical asperities and fault strain rates. The presence of clay minerals and the strain rate experienced by fault rocks modulate the shifting from cataclasis-dominated towards pressure-solution-dominated deformation. Resulting structural heterogeneity of these faults may mirror their mechanical and seismic behaviour: we suggest that seismic asperities are located at the boundaries of massive limestones in narrow zones of localized slip whereas weak shear zones constitute slowly slipping portions of the fault, reflecting other types of “aseismic” behaviour.