Submarine channels deliver globally important volumes of sediments, nutrients, contaminants and organic carbon into the deep sea. Knickpoints are significant topographic features found within numerous submarine channels, which most likely play an important role in channel evolution and the behaviour of the submarine sediment-laden flows (turbidity currents) that traverse them. Although prior research has linked supercritical turbidity currents to the formation of both knickpoints and smaller crescentic bedforms, the relationship between flows and the dynamics of these seafloor features remains poorly constrained at field-scale. This study investigates the distribution, variation and interaction of knickpoints and crescentic bedforms along the 44 km long submarine channel system in Bute Inlet, British Columbia. Wavelet analyses on a series of repeated bathymetric surveys reveal that the floor of the submarine channel is composed of a series of knickpoints that have superimposed, higher-frequency, crescentic bedforms. Individual knickpoints are separated by hundreds to thousands of metres, with the smaller superimposed crescentic bedforms varying in wavelengths from ca 16 m to ca 128 m through the channel system. Knickpoint migration is driven by the passage of frequent turbidity currents, and acts to redistribute and reorganize the crescentic bedforms. Direct measurements of turbidity currents indicate the seafloor reorganization caused by knickpoint migration can modify the flow field and, in turn, control the location and morphometry of crescentic bedforms. A transect of sediment cores obtained across one of the knickpoints show sand–mud laminations of deposits with higher aggradation rates in regions just downstream of the knickpoint. The interactions between flows, knickpoints and bedforms that are documented here are important because they likely dominate the character of preserved submarine channel-bed deposits.

中文翻译：

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水下通道中的拐点和新月形床相互作用

海底通道将全球重要的沉积物，营养物，污染物和有机碳输送到深海。拐点是在众多海底河道中发现的重要地形特征，最有可能在河道演变以及横穿海底沉积物的水流（浊流）的行为中发挥重要作用。尽管先前的研究已经将超临界浊流与拐点和较小的月牙形床状的形成联系在一起，但是在田间尺度上，流动与这些海底特征的动力学之间的关系仍然受到限制。这项研究调查了不列颠哥伦比亚省Bute Inlet沿44 km长的海底河道系统的拐点和新月形床的分布，变化和相互作用。对一系列重复的测深调查的小波分析表明，海底通道的底部由一系列叠加了较高频率的月牙形床身的拐点组成。各个拐点之间相隔数百至数千米，较小的叠加月牙形床体的波长从通过通道系统大约16 m至大约128 m。拐点迁移是由频繁的浊流的通过引起的，并起到重新分布和重新组织新月形床形的作用。对浊流的直接测量表明，由拐点移动引起的海底重组可以改变流场，进而控制新月形床的位置和形态。跨一个拐点获得的沉积物岩心的横断面显示，在拐点下游的区域，沉积物的砂泥积层具有更高的凝结速率。此处记录的流，拐点和床形之间的相互作用很重要，因为它们可能主导着海底通道床沉积物的保存特性。