Rapidly-migrating and internally-generated knickpoints can control submarine channel evolution
Rapidly-migrating and internally-generated knickpoints can control submarine channel evolution
复制标题
DOI：
10.1038/s41467-020-16861-x
复制
发表时间：
2020-06-19
影响因子：
16.6
通讯作者：
Clarke, John E. Hughes
中科院分区：
文献类型：
--
作者：
Heijnen, Maarten S.;Clare, Michael A.;Clarke, John E. Hughes
海底通道是陆地沉积物、有机碳和污染物向深海输送的主要通道。海底水道比河流更难监测，因此也更不容易了解。在这里，我们提出了9年的时间推移映射的一个活跃的海底通道沿着其全长在布特湾，加拿大。过去的研究表明，曲流-弯曲迁移、堤沉积或（超临界流）底形迁移控制了海底通道的演化。我们第一次展示了如何快速（100- 450米/年）上游迁移5-30米高的断点可以控制海底通道的演变。与断点迁移相关的变化包括深（> 25米）侵蚀和河道的侧向迁移。河流中的断点是由外部因素造成的，如构造或基准面变化。但是，布特进气道内的断点似乎是内部产生的。在世界各地的几个海底通道中也发现了类似的断点，因此对通道的运作方式具有全球重要性。作者分析了不列颠哥伦比亚省（CA）布特湾9年的延时测量，以显示活跃的海底通道是如何演变的。它们显示了河道演变是如何由陡峭的断点（类似于河流中的瀑布）的快速上游迁移控制的。
Submarine channels are the primary conduits for terrestrial sediment, organic carbon, and pollutant transport to the deep sea. Submarine channels are far more difficult to monitor than rivers, and thus less well understood. Here we present 9 years of time-lapse mapping of an active submarine channel along its full length in Bute Inlet, Canada. Past studies suggested that meander-bend migration, levee-deposition, or migration of (supercritical-flow) bedforms controls the evolution of submarine channels. We show for the first time how rapid (100-450m/year) upstream migration of 5-to-30 m high knickpoints can control submarine channel evolution. Knickpoint migration-related changes include deep (>25m) erosion, and lateral migration of the channel. Knickpoints in rivers are created by external factors, such as tectonics, or base-level change. However, the knickpoints in Bute Inlet appear internally generated. Similar knickpoints are found in several submarine channels worldwide, and are thus globally important for how channels operate. The authors analyse 9 years of time-lapse surveys in Bute Inlet, British Columbia (CA), to show how an active submarine channel evolves. They show how channel evolution is controlled by fast upstream-migration of steep knickpoints, which are similar to waterfalls in rivers.