Longest sediment flows yet measured show how major rivers connect efficiently to deep sea
Talling, Peter J.; Baker, Megan L.; Pope, Ed L.; Ruffell, Sean C.; Jacinto, Ricardo Silva; Heijnen, Maarten S.; Hage, Sophie; Simmons, Stephen M.; Hasenhündl, Martin; Heerema, Catharina J.; McGhee, Claire; Apprioual, Ronan; Ferrant, Anthony; Cartigny, Matthieu J. B.; Parsons, Daniel R.; Clare, Michael A.; Tshimanga, Raphael M.; Trigg, Mark A.; Cula, Costa A.; Faria, Rui; Gaillot, Arnaud; Bola, Gode; Wallance, Dec; Griffiths, Allan; Nunny, Robert; Urlaub, Morelia; Peirce, Christine; Burnett, Richard; Neasham, Jeffrey; Hilton, Robert J. (2022). Longest sediment flows yet measured show how major rivers connect efficiently to deep sea. Nature Comm. 13(1): 4193. https://dx.doi.org/10.1038/s41467-022-31689-3
In: Nature Communications. Nature Publishing Group: London. ISSN 2041-1723; e-ISSN 2041-1723, more
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| Abstract |
Here we show how major rivers can efficiently connect to the deep-sea, by analysing the longest runout sediment flows (of any type) yet measured in action on Earth. These seafloor turbidity currents originated from the Congo River-mouth, with one flow travelling >1,130 km whilst accelerating from 5.2 to 8.0 m/s. In one year, these turbidity currents eroded 1,338-2,675 [>535-1,070] Mt of sediment from one submarine canyon, equivalent to 19–37 [>7–15] % of annual suspended sediment flux from present-day rivers. It was known earthquakes trigger canyon-flushing flows. We show river-floods also generate canyon-flushing flows, primed by rapid sediment-accumulation at the river-mouth, and sometimes triggered by spring tides weeks to months post-flood. It is demonstrated that strongly erosional turbidity currents self-accelerate, thereby travelling much further, validating a long-proposed theory. These observations explain highly-efficient organic carbon transfer, and have important implications for hazards to seabed cables, or deep-sea impacts of terrestrial climate change. |
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