Origin of deformation bands in argillaceous sediments at the toe of the Nankai accretionary prism, southwest Japan
Origin of deformation bands in argillaceous sediments at the toe of the Nankai accretionary prism, southwest Japan
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DOI：
10.1016/j.jsg.2003.06.001
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发表时间：
2004-02
影响因子：
3.1
通讯作者：
K. Ujiie;A. Maltman;M. Sánchez-Gómez
中科院分区：
文献类型：
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作者：
K. Ujiie;A. Maltman;M. Sánchez-Gómez
南开增生棱柱顶部泥质沉积物中的变形带大致为平面的、厚1~10 mm的顺层-斜带。这些带通常发育为两个相反的倾斜组。一组带可以被相反倾斜的带的光滑表面移位，显示出相对于水平面的反向滑动。变形带通常由较薄的子带组成，这些子带倾斜或平行于变形带的边界。子带还显示出相对于水平面的反向滑动，并且子带内的粒子的方向与最大主应力(σ1)垂直，而与子带的倾角无关。用X射线计算机断层扫描仪进行的物理性能分析表明，相对于周围未变形的材料，变形带中的孔隙率减少了1%至6%。变形带是与北西向板块汇聚有关的近水平σ1下形成的紧凑剪切带，亚带是反向剪切和垂直于σ1展平的组合产生的，它们的几何形状产生了在剪切粘土质沉积物或韧性变质剪切带中观察到的S-C向。
Deformation bands in argillaceous sediments at the toe of the Nankai accretionary prism are roughly planar, ∼1–10 mm thick, bedding-oblique zones. The bands are typically developed as two oppositely dipping sets. A band of one set can be displaced by the slickenlined surface of the oppositely dipping band, showing a reverse slip with respect to a horizontal plane. Deformation bands commonly consist of thinner subbands that are oblique or parallel to the boundaries of the deformation bands. The subbands also display a reverse slip with respect to a horizontal plane, and particles within subbands are oriented perpendicular to the maximum principal stress (σ1), regardless of the dips of the subbands. Physical property analysis using an X-ray computed tomography scanner demonstrates that porosity reduction in the deformation bands relative to the surrounding undeformed material ranges from 1 to 6%. The deformation bands are compactive shear bands formed under subhorizontal σ1associated with northwest-directed plate convergence, and subbands arise from a combination of reverse sense of shear and flattening perpendicular to σ1, with their geometries producing the S–C aspect observed in sheared clayey sediments or ductile metamorphic shear zones.