Normal faults at same depth as thrust faults in an exhumed accretionary complex, Kayo Formation, Okinawa Islands, Japan
Normal faults at same depth as thrust faults in an exhumed accretionary complex, Kayo Formation, Okinawa Islands, Japan
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日本冲绳群岛 Kayo 组挖出的增生杂岩中与逆冲断层深度相同的正断层
DOI：
10.1130/2018.2534
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Ujiie Kohtaro
中科院分区：
文献类型：
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作者：
Hashimoto Yoshitaka;Ueda Dai;Motomiya Yuhei;Tobe Kota;Saiki Ayaka;Morita Kiyohiko;Ujiie Kohtaro
俯冲逆冲界面代表了一个与流体生成、流动和逃逸相耦合的集中变形区。在这里，我们审查的巨型逆冲断层的内部结构暴露在挖出的增生复合体，我们确定了一个变形序列，开发的材料进入沟槽是通过孕震区俯冲。软沉积物中的初始韧性流动产生肢解、褶皱和石香肠状层理，这些层理被后来的脆性不连续面横切。矿脉形成沿着早期断层，并填充水力裂隙与相同的延伸方向的石香肠在床上，证明流体辅助的质量转移过程中的浅过渡，从韧性流动到脆性变形。在较高变质等级的岩石中，矿脉横切叶理由矿物组合定义，在超过地震带底部温度的温度下保持稳定。然而，静脉本身的韧性变形的扩散和/或位错蠕变，因此，他们记录断裂和流体流动在一个更深的脆韧性过渡。
The subduction thrust interface represents a zone of concentrated deformation coupled to fluid generation, flow, and escape. Here, we review the internal structure of the megathrust as exposed in exhumed accretionary complexes, and we identify a deformation sequence that develops as material entering the trench is subducted through the seismogenic zone. Initial ductile flow in soft sediment generates dismembered, folded, and boudinaged bedding that is crosscut by later brittle discontinuities. Veins formed along early faults, and filling hydrofractures with the same extension directions as boudins in bedding, attest to fluid-assisted mass transfer during the shallow transition from ductile flow to brittle deformation. In higher-metamorphic-grade rocks, veins crosscut foliations defined by mineral assemblages stable at temperatures beyond those at the base of the seismogenic zone. The veins are, however, themselves ductilely deformed by diffusion and/or dislocation creep, and thus they record fracture and fluid flow at a deeper brittle-to-ductile transition.