Congo Canyon

{{Short description|African submarine canyon at the end of the Congo River}} {{Location map+|Africa|relief=1|float=right|caption=Location near Africa |places={{Location map~|Africa|lat=-5.98|long=11.73|label=Congo Canyon|position=left|mark=Red pog.svg}}}}

thumbnail|right|Satellite image of Congo Canyon in the Atlantic Ocean off the coast of Africa

'''Congo Canyon''' is a submarine canyon found at the end of the Congo River in Africa. It is one of the largest submarine canyons in the world.<ref name="heezen">{{cite journal|last1=Heezen|first1=B.C.|title=Congo Submarine Canyon|journal=Bulletin of the American Association of Petroleum Geologists|date=July 1964|volume=48|issue=7|pages=1128–1149|url=http://archives.datapages.com/data/bulletns/1961-64/data/pg/0048/0007/1100/1126.htm|accessdate=17 March 2016|display-authors=etal}}</ref>

==Size== The canyon begins inland on the continent, partway up the Congo Estuary, and starts at a depth of 21 meters. It cuts across the entire continental shelf for 85 kilometers until it reaches the shelf edge, then continues down the slope and ends 280 km from where it started. At its deepest point, the V-shaped canyon walls are 1,100 meters tall, and the maximum width of the canyon is about 9 miles (14 km).<ref name="britannica">{{cite web|title=Congo Canyon|url=http://academic.eb.com/EBchecked/topic/132456/Congo-Canyon|website=Encyclopædia Britannica Academic|publisher=Encyclopædia Britannica Inc.|accessdate=17 March 2016}}</ref> At the bottom of the continental slope, it enters the Congo deep-sea fan and extends for an additional 220 km.

==Turbidity currents== thumb|Turbidity Current Diagram The turbidity currents found in Congo Canyon are the strongest measured in the world.<ref name="OTC">{{cite web|last1=Cooper|first1=Cortis|last2=Wood|first2=Jon|last3=Andrieux|first3=Olivier|title=Turbidity Current Measurements in the Congo Canyon|url=https://www.onepetro.org/download/conference-paper/OTC-23992-MS?id=conference-paper%2FOTC-23992-MS|website=www.onepetro.org|publisher=Offshore Technology Conference|accessdate=7 April 2016}}</ref> These are essentially underwater avalanches that can propagate for hundreds of kilometers, and their strength and frequency correlate strongly with the period of highest outflow from the Congo River. Their speeds vary from about 0.7 m/s to 3.5 m/s and events can last for more than a week.<ref name="DSResearch">{{cite journal|last1=Vangriesheim|first1=Annick|last2=Khripounoff|first2=Alexis|last3=Crassous|first3=Philippe|title=Turbidity events observed in situ along the Congo submarine channel|journal=Deep-Sea Research Part II: Topical Studies in Oceanography|date=November 2009|volume=56|issue=23|pages=2208–2222|doi=10.1016/j.dsr2.2009.04.004|bibcode=2009DSRII..56.2208V|url=http://archimer.ifremer.fr/doc/2009/publication-6738.pdf|accessdate=7 April 2016}}</ref> These currents are the major source of erosion in the canyon and represent a significant portion of the sediment that ends up in the fan at the end of the canyon. They commonly destroy equipment laid on the bottom of the ocean and have destroyed telegraph cables and moorings.<ref name= "heezen"/>

==Congo Deep-Sea Fan== The Congo Deep-Sea Fan accounts for a surface of about 300,000 km<sup>2</sup> and at least 0.7 Mkm<sup>3</sup> of Cenozoic sediments, becoming one of the largest submarine fan systems in the world.<ref>{{cite journal |last1=Anka |first1=Zahie |last2=Séranne |first2=Michel |last3=Lopez |first3=Michel |last4=Scheck-Wenderoth |first4=Magdalena |last5=Savoye |first5=Bruno |title=The long-term evolution of the Congo deep-sea fan: A basin-wide view of the interaction between a giant submarine fan and a mature passive margin (ZaiAngo project) |journal=Tectonophysics |date=17 May 2009 |volume=470 |issue=1 |pages=42–56 |doi=10.1016/j.tecto.2008.04.009 |bibcode=2009Tectp.470...42A |url=https://archimer.ifremer.fr/doc/00000/6634/ }}</ref> The fan extends over 1000 km from the Congo-Angola coast and was developed after the early Cretaceous rifting. The sediments includes quartz grains. <ref name='Garzanti'>{{cite journal |last1=Garzanti |first1=Eduardo |last2=Bayon |first2=Germain |last3=Dennielou |first3=Bernard |last4=Barbarano |first4=Marta |last5=Limonta |first5=Mara |last6=Vezzoli |first6=Giovanni |title=The Congo deep-sea fan: Mineralogical, REE, and Nd-isotope variability in quartzose passive-margin sand |journal=Journal of Sedimentary Research |date=14 May 2021 |volume=91 |issue=5 |pages=433–450 |doi=10.2110/jsr.2020.100 |bibcode=2021JSedR..91..433G |s2cid=236401511 |url=https://archimer.ifremer.fr/doc/00694/80618/83873.pdf }}</ref>

The connection through the Congo submarine canyon allowed the direct transfer of terrestrial materials to the abyssal zone of the fan system.<ref name='Garzanti' /> Unlike other rivers that empty into the sea, the Congo River is not building a delta because essentially all of its sediments are carried by turbidity currents via the submarine canyon to the fan. This accumulation is probably the greatest in the world for a currently active submarine system.<ref name="savoye">{{cite journal|last1=Savoye|first1=Bruno|last2=Babonneau|first2=Nathalie|last3=Dennielou|first3=Bernard|last4=Bez|first4=Martine|title=Geological overview of the Angola–Congo margin, the Congo deep-sea fan and its submarine valleys|journal=Deep-Sea Research Part II: Topical Studies in Oceanography|date=November 2009|volume=56|issue=23|pages=2169–2182|doi=10.1016/j.dsr2.2009.04.001|bibcode=2009DSRII..56.2169S|url=https://archimer.ifremer.fr/doc/00000/11128/7848.pdf}}</ref> The fan is built up by sediment gravity flows and other submarine mass movements, but also represents a very large active turbidite system. Although there exists a net up-canyon bottom current due to upwelling,<ref name="marshall">{{cite web|last1=Marshall Crossland|first1=J.I.|last2=Crossland|first2=C.J.|last3=Swaney|first3=D.P.|title=Congo (Zaire) River Estuary, Democratic Republic of the Congo|url=http://nest.su.se/mnode/Africa/Congo/Congobud.htm|website=Baltic Nest Institute|accessdate=17 March 2016}}</ref> these events overwhelm the normal bottom flow and ensure continued deposition.

==References== {{reflist}}

Category:Submarine canyons of the Atlantic Ocean