Triggering and Evolution of a Giant Submarine Landslide, Offshore Angola, Revealed by 3D Seismic Stratigraphy and Geomorphology
Triggering and Evolution of a Giant Submarine Landslide, Offshore Angola, Revealed by 3D Seismic Stratigraphy and Geomorphology
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DOI：
10.2110/jsr.2006.02
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发表时间：
2006
影响因子：
2
通讯作者：
M. Gee;R. Gawthorpe;S. J. Friedmann
中科院分区：
文献类型：
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作者：
M. Gee;R. Gawthorpe;S. J. Friedmann
摘要利用三维地震资料对安哥拉近海海底大型滑坡复合体的震源区进行了成像。三维地震数据显示，侵蚀性滑痕、滑坡块体和泥石流涉及的物质大于20 km 3，影响面积大于430 km 2。基底和内部结构的详细成像显示基底侵蚀和证据，至少有三个阶段的滑坡失败。滑坡内部结构揭示了海底滑坡破坏初始阶段海底再活化的证据。缺失的地层和底部滑动面上15 m深、9 km长的下坡走向条纹记录了超过130 km 2面积的初始破坏。基底条纹起源于一个走向西北-东南的主要生长断层，并从该断层向下坡延伸。我们推测，流体流动或地震活动与这个生长断层触发滑坡。滑坡存款由大块（约1至> 5公里，约100至150米厚），其中滑动，旋转，并在混乱的泥石流矩阵内的滑坡变形。一个更平滑的泥石流形态从侵蚀疤痕和块体延伸到超出调查区域边界的东南部。滑坡几何形状的粗略估计表明，存款量是两倍的侵蚀滑痕5公里内的源。本研究的观测结果总结在一个面向过程的滑坡模型。结果提供了深入了解触发，演变，和潜在的巨大的海底滑坡。
Abstract The source area of a large submarine landslide complex has been imaged in the subsurface off Angola using 3D seismic data. The 3D seismic data reveal erosional slide scars, landslide blocks, and debris flows involving > 20 km3 material, affecting an area > 430 km2. The basal and internal structure is imaged in detail showing basal erosion and evidence for at least three phases of landslide failure. Landslide internal structure reveals evidence for seafloor remobilization during the initial phase of submarine landslide failure. Missing strata and downslope-trending striations 15 m deep and 9 km long on the basal sliding surface record the initial failure over an area > 130 km2. The basal striations originate from and extend downslope from a major growth fault trending NW–SE. We speculate that fluid flow or seismicity associated with this growth fault triggered landsliding. The landslide deposit consists of large blocks (~ 1 to > 5 km across and ~ 100 to 150 m thick) which have slid, rotated, and deformed in the landslide within a chaotic debris-flow matrix. A smoother debris-flow morphology extends from the erosional scars and blocks to the SE beyond the boundaries of the survey area. A rough estimate of landslide geometry indicates that the deposit volume is double the volume of erosional slide scars within 5 km of source. The observations from this study are summarized in a process-oriented landslide model. Results provide insight into the triggering, evolution, and runout potential of giant submarine landslides.