Evolution of Riedel-shear pop-up structures during cumulative strike-slip faulting: A case study in the Misayama-Godo area, Fujimi Town, central Japan
Evolution of Riedel-shear pop-up structures during cumulative strike-slip faulting: A case study in the Misayama-Godo area, Fujimi Town, central Japan
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累积走滑断层过程中 Riedel 剪切弹出构造的演化：以日本中部富士见镇 Misayama-Godo 地区为例
DOI：
10.1016/j.geomorph.2018.11.026
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发表时间：
2019
期刊：
影响因子：
3.9
通讯作者：
and Y. Suzuki
中科院分区：
文献类型：
--
作者：
Sugito;N.;H. Sawa;K. Taniguchi;Y. Sato;M. Watanabe;and Y. Suzuki
走滑断层常发育由里德尔剪切引起的埃涅克伦断层作用。当断裂的基岩被厚厚的松散沉积覆盖时，这种埃舍隆断裂导致在累积位移期间沿着断裂的一系列弹出物的随后演化。尽管以前的砂箱实验和数值模拟已经研究了Riedel剪切弹出结构形成的演化过程，但关于(1)弹出结构形成的演化过程的时间序列和(2)达到“贯通断裂带”阶段所需的时间段的现场实例迄今鲜有报道。Itoigawa-Shizuoka构造线(ISTL)断裂带是日本规模最大、滑动速度最快的活动断裂带之一，在该断裂带中南部的Fujimi地区发育了一系列与左旋走滑位移有关的构造突起。该地区被厚(约820 m)的松散矿床覆盖，形成了里德尔-剪切弹出构造。通过对富士三山-后藤区一弹出构造的地貌分析、广泛的钻探调查和坑探调查，得出如下结论：(1)三山-后藤地区的弹出构造是由~100 ka和~10-20 ka之间的两条边缘断裂构成的；(2)自~10-20 ka以来，断层的深部位移主要集中在贯穿弹出构造(对应于“贯通断裂带”)的断层上。在ISTL断裂带中南部最近的一次地震中，穿过弹出式构造的其中一个断层可能滑动了。这项研究是里德尔剪切弹出构造在累积走滑断裂过程中演化的一个稳健的现场实例。
Strike-slip faulting often develops en échelon faulting resulting from Riedel shears. When faulted basement rocks are covered by thick unconsolidated deposits, this en échelon faulting leads to the subsequent evolution of a series of pop-ups along the fault during cumulative displacement. Although previous sandbox experiments and numerical simulations have examined the evolutionary processes for Riedel-shear pop-up structure formation, few field examples have been reported until now concerning (1) the time-series of evolutionary processes of pop-up structure generation and (2) time periods necessary to reach the stage of a “throughgoing fault zone”. The Itoigawa-Shizuoka Tectonic Line (ISTL) fault zone is among the largest and fastest-slipping active fault zones in Japan, and a series of tectonic pop-ups related to left-lateral strike-slip displacement have developed in the Fujimi area in the central to southern part of the fault zone. This area is covered by thick (~820 m) unconsolidated deposits, which have resulted in Riedel-shear pop-up structures. We conducted a geomorphic analysis, an extensive drilling survey, and pit excavation survey on a pop-up in the Misayama-Godo area of Fujimi, and concluded that (1) the pop-up structures in the Misayama-Godo area have been built up by two marginal faults between ~100 ka and ~10–20 ka, and (2) the fault displacement at depth has been concentrated on the faults that run across the pop-up structures (corresponding to the “throughgoing fault zone”) since ~10–20 ka. One of the faults that run across the pop-up structures probably slipped during the most recent earthquake in the central to southern part of the ISTL fault zone. This study is presented as a robust field example of the evolution of Riedel-shear pop-up structures during cumulative strike-slip faulting.