首页> 外文期刊>Journal of structural geology >Growth of cataclastic bands into a fault zone: A multiscalar process by microcrack coalescence in sandstones of Rio do Peixe Basin, NE Brazil
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Growth of cataclastic bands into a fault zone: A multiscalar process by microcrack coalescence in sandstones of Rio do Peixe Basin, NE Brazil

机译:地震带入故障区的水分弹性带的生长:在里约的砂岩中微裂纹加工的多学分过程Do Beixe Basin,Ne Brazil

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We propose a structural evolutionary model for deformation band (DB) development via microcrack propagation and coalescence process in a normal fault zone affecting arkosic sandstones. Based on structural analysis and reconstruction of the paleostress, we infer that a sub-horizontal minimum principal stress (?3) in the NNW-SSE direction controlled the multiscalar evolution of microcracks and DBs. Two main sets of coalesced microcracks and DBs are recognized: (1) NE-SW and (2) E-W, in which the coalescence pattern of microcracks is also observed among the DBs at meso-scale. Our results suggest that the DBs develop during three deformation stages: (1) pore collapse followed by initial grain breakage and the formation of NE-SW tensile microcracks favoured by cleavage planes in feldspars. These microcracks coalesce through linking NW-SE shear microcracks to form intermediary microplanes. An intense microcracking crush the grains, enhancing the cataclastic process. The further coalescence of these intermediary microplanes with other intermediary microplanes and/or microcracks might generate through-going microplanes inside the band, causing the formation of E-W DBs; (2) the E-W structures coalesce through NE-SW hard-linking DBs, which corresponds to the DBs clusters, generating NE-SW intermediary planes at meso-scale; (3) the NE-SW intermediary planes coalesce through an E-W hard-linking structure, which results in the DB fault zone.
机译:我们在影响Arkosic Sandstones的正常断裂带中通过微裂纹传播和聚结过程提出了一种变形带(DB)开发的结构进化模型。基于古老人构的结构分析和重建,我们推断NNW-SSE方向中的亚水平最小主应力(?3)控制了微分子和DBS的MultiScalar演化。识别出两个主要的聚结微裂纹和DBS:(1)NE-SW和(2)E-W,其中在中间尺度的DBS中也观察到微裂纹的聚结模式。我们的研究结果表明,DBS在三个变形阶段发育:(1)孔隙塌陷随后初始晶粒破裂以及在长石中裂解裂解面的Ne-SW拉伸微裂纹的形成。这些微裂纹通过将NW-SE剪切微裂纹连接以形成中间微覆盖物。一种强烈的微裂纹压碎谷物,增强了Cataclastic过程。这些中间微铝和/或微裂纹的这些中间微铝的进一步聚结可能在带内产生通过流动的微观,导致E-W DBS的形成; (2)E-W结构通过NE-SW硬链接DBS合并,该DBS对应于DBS集群,在中间级生成NE-SW中间平面; (3)NE-SW中介飞机通过E-W的硬链接结构聚结,这导致DB断层区域。

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