Newly recognized turbidity current structure can explain prolonged flushing of submarine canyons.
Newly recognized turbidity current structure can explain prolonged flushing of submarine canyons.
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DOI：
10.1126/sciadv.1700200
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发表时间：
2017-10
期刊：
影响因子：
13.6
通讯作者：
Pope EL
中科院分区：
文献类型：
--
作者：
Azpiroz-Zabala M;Cartigny MJB;Talling PJ;Parsons DR;Sumner EJ;Clare MA;Simmons SM;Cooper C;Pope EL
浊流奔涌延伸至深海，形成了地球上最大的沉积物堆积。
被称为浊流的贴近海底的水流，是在地球上搬运沉积物的体积上最重要的过程，并形成了最大的沉积物堆积。我们试图通过重新分析对海洋浊流内部速度和密度所做的最详细的直接测量来了解浊流的内部结构和行为，这些测量数据来自刚果峡谷中持续一周的水流。我们为浊流结构提供了一个新模型，该模型可以解释为什么这些浊流比之前监测到的所有海洋浊流持续时间长得多，之前在其他位置监测到的浊流仅持续数小时或数分钟。观测到的刚果峡谷水流在前端包含一个快速且密集的流体短寿区，它比水流中移动较慢的主体部分流速更快。我们认为这些浊流的持续时间是由水流拉伸造成的，并且这种拉伸是富含泥沙的浊流系统的特征。之前监测到的水流中缺乏拉伸是由于较粗的沉积物从主体中更快地沉降。这些长时间持续的海底水流可与刚果河的流量相媲美，并且每年通过单个海底峡谷携带约2%全球埋藏在海洋中的陆地有机碳。因此，这种新结构解释了全球重要数量的沉积物、有机碳、营养物质和淡水持续冲入深海的原因。
Runaway turbidity currents stretch into the deep ocean to form the largest sediment accumulations on Earth. Seabed-hugging flows called turbidity currents are the volumetrically most important process transporting sediment across our planet and form its largest sediment accumulations. We seek to understand the internal structure and behavior of turbidity currents by reanalyzing the most detailed direct measurements yet of velocities and densities within oceanic turbidity currents, obtained from weeklong flows in the Congo Canyon. We provide a new model for turbidity current structure that can explain why these are far more prolonged than all previously monitored oceanic turbidity currents, which lasted for only hours or minutes at other locations. The observed Congo Canyon flows consist of a short-lived zone of fast and dense fluid at their front, which outruns the slower moving body of the flow. We propose that the sustained duration of these turbidity currents results from flow stretching and that this stretching is characteristic of mud-rich turbidity current systems. The lack of stretching in previously monitored flows is attributed to coarser sediment that settles out from the body more rapidly. These prolonged seafloor flows rival the discharge of the Congo River and carry ~2% of the terrestrial organic carbon buried globally in the oceans each year through a single submarine canyon. Thus, this new structure explains sustained flushing of globally important amounts of sediment, organic carbon, nutrients, and fresh water into the deep ocean.
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影响因子：
16.6
作者：
de Leeuw J;Eggenhuisen JT;Cartigny MJ
通讯作者：
Cartigny MJ
影响因子：
2.4
作者：
DOWNING, A;THORNE, PD;VINCENT, CE
通讯作者：
VINCENT, CE
DOI：
10.1016/j.dsr2.2017.03.010
发表时间：
2017-08-01
影响因子：
3
作者：
Dennielou, Bernard;Droz, Laurence;Rabouille, Christophe
通讯作者：
Rabouille, Christophe
影响因子：
2.4
作者：
FRANCOIS, RE;GARRISON, GR
通讯作者：
GARRISON, GR
影响因子：
1.8
作者：
MILLIMAN, JD;SYVITSKI, JPM
通讯作者：
SYVITSKI, JPM