Carbon and sediment fluxes inhibited in the submarine Congo Canyon by landslide-damming
Carbon and sediment fluxes inhibited in the submarine Congo Canyon by landslide-damming
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DOI：
10.1038/s41561-022-01017-x
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发表时间：
2022-09
影响因子：
18.3
通讯作者：
E. Pope;M. Heijnen;P. Talling;R. Jacinto;A. Gaillot;Megan L. Baker;S. Hage;M. Hasenhündl;C. Heerema;C. McGhee;Sean C. Ruffell;S. Simmons;M. Cartigny;M. Clare;B. Dennielou;D. Parsons;C. Peirce;M. Urlaub
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文献类型：
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作者：
E. Pope;M. Heijnen;P. Talling;R. Jacinto;A. Gaillot;Megan L. Baker;S. Hage;M. Hasenhündl;C. Heerema;C. McGhee;Sean C. Ruffell;S. Simmons;M. Cartigny;M. Clare;B. Dennielou;D. Parsons;C. Peirce;M. Urlaub
滑坡坝往往是瞬变的，它会对水下河流系统内的地貌、沉积物和地球化学通量产生强烈影响。然而，由于缺乏足够的时间分辨观测，海底峡谷中类似滑坡大坝的潜在发生和影响一直难以确定。在这里，我们介绍了从2005年到2019年对西非近海的一个主要的海底峡谷--刚果峡谷进行的重复水深测量。我们展示了一场约0.09 的峡谷侧翼滑坡是如何筑坝于峡谷的，导致另外约0.4 km3的沉积物暂时储存，其中包含约5 Mt的主要陆地有机碳。被困泥沙厚度达150 m，并延伸至滑坡坝峡谷上方&26 公里处。这些泥沙是由浊流输送的，泥沙负荷被滑坡坝俘获。我们的结果表明，峡谷两侧的塌陷可以是对峡谷形态的重要控制，因为它们可以产生或促成曲折断裂带、灯笼点和阶地的形成。侧翼塌陷有可能调节沉淀物和流向深海的地球化学通量，并可能影响主要海底峡谷作为运输管道和有机碳固存地点的效率。这对依赖通过海底峡谷运输的有机碳的深海生态系统具有潜在的后果。
Landslide-dams, which are often transient, can strongly affect the geomorphology, and sediment and geochemical fluxes, within subaerial fluvial systems. The potential occurrence and impact of analogous landslide-dams in submarine canyons has, however, been difficult to determine due to a scarcity of sufficiently time-resolved observations. Here we present repeat bathymetric surveys of a major submarine canyon, the Congo Canyon, offshore West Africa, from 2005 and 2019. We show how an ~0.09 km3canyon-flank landslide dammed the canyon, causing temporary storage of a further ~0.4 km3of sediment, containing ~5 Mt of primarily terrestrial organic carbon. The trapped sediment was up to 150 m thick and extended >26 km up-canyon of the landslide-dam. This sediment has been transported by turbidity currents whose sediment load is trapped by the landslide-dam. Our results suggest canyon-flank collapses can be important controls on canyon morphology as they can generate or contribute to the formation of meander cut-offs, knickpoints and terraces. Flank collapses have the potential to modulate sediment and geochemical fluxes to the deep sea and may impact efficiency of major submarine canyons as transport conduits and locations of organic carbon sequestration. This has potential consequences for deep-sea ecosystems that rely on organic carbon transported through submarine canyons.