Which Triggers Produce the Most Erosive, Frequent, and Longest Runout Turbidity Currents on Deltas?
Which Triggers Produce the Most Erosive, Frequent, and Longest Runout Turbidity Currents on Deltas?
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DOI：
10.1002/2017gl075751
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发表时间：
2017-12
影响因子：
5.2
通讯作者：
J. Hizzett;J. Clarke;E. Sumner;M. Cartigny;P. Talling;M. Clare
中科院分区：
文献类型：
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作者：
J. Hizzett;J. Clarke;E. Sumner;M. Cartigny;P. Talling;M. Clare
陆上河流和浊流是地球上两种最大规模的沉积物搬运过程，了解它们在河口近海处是如何联系的非常重要。此前，人们认为斜坡失稳或河流洪水的直接倾泻（高密度流）主导了三角洲前缘浊流的触发。在此，我们重新分析了对一个水下三角洲迄今最详细的延时监测，包括对加拿大不列颠哥伦比亚省斯阔米什三角洲的93次勘测。我们表明，大多数浊流是由稀释的地表河羽流中的沉积物沉降触发的，而非滑坡或高密度流。由沉降羽流触发的浊流频繁发生，其延伸距离与滑坡触发的事件一样远，并对三角洲和叶状体形态造成最大的改变。我们首次表明，地表羽流的沉降可主导危险的海底水流和近海沉积物通量的触发。
Subaerial rivers and turbidity currents are the two most voluminous sediment transport processes on our planet, and it is important to understand how they are linked offshore from river mouths. Previously, it was thought that slope failures or direct plunging of river floodwater (hyperpycnal flow) dominated the triggering of turbidity currents on delta fronts. Here we reanalyze the most detailed time‐lapse monitoring yet of a submerged delta; comprising 93 surveys of the Squamish Delta in British Columbia, Canada. We show that most turbidity currents are triggered by settling of sediment from dilute surface river plumes, rather than landslides or hyperpycnal flows. Turbidity currents triggered by settling plumes occur frequently, run out as far as landslide‐triggered events, and cause the greatest changes to delta and lobe morphology. For the first time, we show that settling from surface plumes can dominate the triggering of hazardous submarine flows and offshore sediment fluxes.