Flow dynamics of Nankai Trough submarine landslide inferred from internal deformation using magnetic fabric
Flow dynamics of Nankai Trough submarine landslide inferred from internal deformation using magnetic fabric
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DOI：
10.1002/2014gc005409
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发表时间：
2014-04
期刊：
影响因子：
3.7
通讯作者：
T. Kanamatsu;K. Kawamura;M. Strasser;B. Novak;Y. Kitamura
中科院分区：
文献类型：
--
作者：
T. Kanamatsu;K. Kawamura;M. Strasser;B. Novak;Y. Kitamura
综合大洋钻探333号考察队对活动俯冲带中的海底滑坡沉积物进行了调查，作为“南海海槽海底滑坡史”。考察队在位于日本西南部纪伊半岛外的南海海槽巨型活动断层下盘斜坡盆地内的C0018站点恢复了一个更新世至全新世的堆积物质搬运沉积序列。从钻孔序列的上部190 m处回收了六个插入相干间隔的大量运输存款单元。质量传输存款单位内的磁化率变化的各向异性被用来确定它们的流变学。形状参数和磁组构取向揭示通过序列的不均匀性，表明不同的压实和剪切发生在个别单元。较年轻单元的上部间隔通常代表在垂直挤压下形成的磁性组构。然而，较低的间隔涉及磁组构，表明横向剪切与深度逐渐变化。在较老的块状运输存款中，磁性叶理的分布形成了紧密折叠的地层，表明与较年轻的块状运输存款单元不同的滑动模式。利用现有的古地磁资料，对单元基底层的剪切方向进行了重新定向，产生了两种不同的滑动方向。水流类型和供水路线的变化被解释为反映坡度条件（例如，斜坡坡度和地震动敏感性），这已被控制的局部构造演化的加积楔。
Submarine landslide deposits in an active subduction zone were investigated by Integrated Ocean Drilling Program Expedition 333 as the “Nankai Trough Submarine Landslides History.” The expedition recovered a Pleistocene to Holocene sequence of stacked mass‐transport deposits at Site C0018, located within a slope basin on the footwall of the megasplay fault in the Nankai Trough off the Kii Peninsula, southwest Japan. Six mass‐transport deposit units intercalated with coherent intervals were recovered from the upper 190 m of the drilled succession. Anisotropy of magnetic susceptibility variations within mass‐transport deposit units was used to ascertain their rheology. Shape parameters and magnetic fabric orientation reveal inhomogeneity through the sequences, indicating that different compaction and shear occurred within individual units. The upper intervals of younger units generally represent a magnetic fabric formed under vertical compression. However, the lower intervals involve magnetic fabrics indicating lateral shear with in‐depth gradual change. In the older mass‐transport deposit, a distribution of magnetic foliation forms tightly folded strata, indicating different sliding patterns from the younger mass‐transport deposit units. Using available paleomagnetic data, the shear directions of basal intervals of units are reoriented, producing two different sliding orientations. Variation in the flow type and supply route is interpreted to reflect the slope condition (e.g., slope gradient and susceptibility to ground motion), which has been controlled by local tectonic evolution of the accretionary wedge.