The processes and deposits of deep‐water submarine channels are known to be influenced by a wide variety of controlling factors, both allocyclic and autocyclic. However, unlike their fluvial counterparts whose dynamics are well‐studied, the factors that control the long‐term behaviour of submarine channels, particularly on slopes undergoing active deformation, remain poorly understood. We combine seismic techniques with concepts from landscape dynamics to investigate quantitatively how the growth of gravitational‐collapse structures at or near the seabed in the Niger Delta have influenced the morphology of submarine channels along their length from the shelf edge to their deep‐water counterpart. From a three dimensional (3D), time‐migrated seismic‐reflection volume, which extends over 120 km from the shelf edge to the base of slope, we mapped the present‐day geomorphic expression of two submarine channels and active structures at the seabed, and created a Digital Elevation Model (DEM). A second geomorphic surface and DEM raster—interpreted to closer approximate the most recent active channel geometries—were created through removing the thickness of hemipelagic drape across the study area. The DEM rasters were used to extract the longitudinal profiles of channel systems with seabed expression, and we evaluate the evolution of channel widths, depths and slopes at fixed intervals downslope as the channels interact with growing structures. Results show that the channel long profiles have a relatively linear form with localized steepening associated with seabed structures. We demonstrate that channel morphologies and their constituent architectural elements are sensitive to active seafloor deformation, and we use the geomorphic data to infer a likely distribution of bed shear stresses and flow velocities from the shelf edge to deep water. Our results give new insights into the erosional dynamics of submarine channels, allow us to quantify the extent to which submarine channels can keep pace with growing structures, and help us to constrain the delivery and distribution of sediment to deep‐water settings.

中文翻译：

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量化尼日尔三角洲大陆坡结构变形与海底河道形态之间的关系

众所周知，深水海底河道的过程和沉积物会受到多种控制因素的影响，包括异位循环和自循环。然而，与对河流动力学研究的深入研究不同，控制海底通道长期行为的因素，特别是在经历主动变形的斜坡上，仍然知之甚少。我们将地震技术与景观动力学概念相结合，以定量研究尼日尔三角洲海床处或附近海床重力塌陷结构的生长如何影响从架子边缘到深水对应部分的海底河道的形态。从三维（3D）随时间迁移的地震反射体中，它从架子边缘延伸到斜坡底部超过120 km，我们绘制了当今海底两个海底通道和活动结构的地貌表示，并创建了数字高程模型（DEM）。通过去除整个研究区域中的半平悬垂的厚度，创建了第二个地貌表面和DEM栅格（被解释为更接近最近的活动通道几何形状）。DEM栅格用于提取具有海床表情的河道系统的纵剖面，并且随着河道与生长结构的相互作用，我们以固定间隔下坡评估河道宽度，深度和坡度的演变。结果表明，河道长剖面具有相对线性的形式，并伴随着与海床结构相关的局部变陡。我们证明了河道形态及其构成的建筑元素对活跃的海底变形敏感，并且我们使用地貌数据推断了床架剪切应力和从层架边缘到深水的流速的可能分布。我们的结果为海底河道的侵蚀动力学提供了新的见解，使我们能够量化海底河道可以与不断增长的结构保持同步的程度，并帮助我们限制沉积物向深水环境的输送和分布。