Preferential formation of a slide plane in translational submarine landslide deposits in a Pleistocene forearc basin fill exposed in east-central Japan
Preferential formation of a slide plane in translational submarine landslide deposits in a Pleistocene forearc basin fill exposed in east-central Japan
复制标题
日本中东部更新世弧前盆地充填物中平移海底滑坡沉积物优先形成滑动面
DOI：
10.1144/sp477.3
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Makoto Otsubo
中科院分区：
文献类型：
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作者：
Masayuki Utsunomiya;Atsushi Noda;Makoto Otsubo
火山灰床被认为是海底滑坡的潜在破坏面。在这里，我们报告了一个影响平移滑动的粗灰/火山灰凝灰岩床的例子。所研究的物质输送沉积物（MTD）夹层于日本中东部暴露的更新世弧前盆地充填物中。该 MTD 由堆积的粉砂岩块组成，这些粉砂岩块是由滑脱处分支的重复叠瓦冲断层形成的。基底滑动面位于富含浮石的粗灰/火山灰凝灰岩床的正下方。构成滑移带的材料被注入到上覆的粗灰/火山灰凝灰岩床中，这表明由于孔隙压力升高而导致多余的孔隙水向上逸出。为了解释这种发生模式，我们认为滑脱优先发生在富含粗灰凝灰岩层段的顶部和底部，该层段似乎相对于邻近的粉砂为主的层段更强。浮石粗灰层和火山灰凝灰岩层表现为高孔隙压力滑动带顶部的刚性板块，维持了平缓大陆坡上的平移滑动。因此，在平移海底滑坡中，滑面的优先形成是由层状沉积物中不同的摩擦阻力引起的。
Tephra beds are considered to be potential failure planes for submarine landslides. Here, we report on an example of a coarse-ash/lapilli-tuff bed influencing translational slides. The studied mass-transport deposit (MTD) is intercalated in the Pleistocene forearc basin fill exposed in east-central Japan. This MTD consists of stacked siltstone blocks resulting from repeated imbricate thrusts branching from the décollement. The basal slide plane is located immediately below a pumice-rich coarse ash/lapilli-tuff bed. The material comprising the slip zone is injected into the overlying coarse-ash/lapilli-tuff bed, suggesting an upwards escape of excess porewater that resulted from elevated pore pressure. To explain this mode of occurrence, we propose that the detachment preferentially occurred at the top and base of the coarse-ash-tuff-rich interval which appears to have been stronger relative to the adjacent silt-dominated interval. The pumiceous coarse-ash and lapilli-tuff bed behaved as a rigid plate on top of the high-pore-pressure slip zone, which sustained the translational slide on the gentle continental slope. Therefore, in translational submarine landslides, the preferential formation of a slide plane is caused by differing frictional resistances in the layered sediments.