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Submarine Canyons and Fans Submarine canyons: major conduits of siliciclastic sediment from the continental shelf to the abyssal plain Submarine fans: accumulations of siliciclastic sediment from the shelf break onto the base of the continental slope.

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  • Submarine Canyons and Fans

    • Submarine canyons: major conduits

      • of siliciclastic sediment from the continental shelf to the abyssal plain

    • Submarine fans: accumulations of

      • siliciclastic sediment from the shelf break onto the base of the continental slope

http://www.dkimages.com/discover/previews/851/20117924.JPG


Submarine canyons basic info
Submarine Canyons (Basic Info)

  • Submarine canyons cut across continental shelves and slopes

  • Carry sediment to the deep ocean basins.

  • Many small submarine canyons and few large ones.

  • Large canyons associated with large coastal rivers.

  • Text from http://www.ocean.uni-bremen.de/EInfo/materialien/elemOc/top12-17/topic13.html

http://www.geol.umd.edu/~jmerck/


Submarine canyons basic info1
Submarine Canyons (Basic Info)

  • Submarine canyons formed, in part, by downcutting of coastal rivers during low sea level.

  • Later continued flow of water and sediment might lead to their further development

  • and extension into the deep sea.

Text from http://www.ocean.uni-bremen.de/EInfo/materialien/elemOc/top12-17/topic13.html


Submarine fans
Submarine Fans

  • Submarine fans are found at mouths of canyons around the world.

http://faculty.gg.uwyo.edu/heller/Sed%

http://www.indiana.edu/~g105lab/images/gaia_chapter_13/sfs026.gif


Submarine fans basic info
Submarine Fans (Basic Info)

  • Submarine fans divided into 3 zones

    • Proximal (upper)

    • Middle

    • Distal (lower)

http://www.geol.umd.edu/~jmerck/geol100/lectures/31.html



Submarine fans transport mechanisms
Submarine Fans: Transport Mechanisms

  • Sediment transport, in general can occur in one of 5 modes:

  • Traction

    • 1. Rolling

    • 2. Sliding

    • 3. Bouncing (saltation)

  • 4. Suspension

  • 5. Mass movement


http://instruct.uwo.ca/earth-sci/200a-001/07turbidity.jpg


Debris flow facies

http://instruct.uwo.ca/earth-sci/200a-001/07turbidity.jpg


http://instruct.uwo.ca/earth-sci/200a-001/07turbidity.jpg

http://serc.carleton.edu/


  • Density Currents ratio

  • Our first quantitative experience with density currents was in

  • 1929 following the M 7.2 Grand Banks Earthquake

Estimated tsunami travel times (in

hours) for waves generated by the 1929

Grand Banks earthquake.

http://www.benfieldhrc.org/activities/hrsr/h&rsr_2005

http://earthquakescanada.nrcan.gc.ca/historic_eq/20th/1929/1929_e.php


Grand banks earthquake
Grand Banks Earthquake ratio

  • Density Currents

  • The earthquake triggered an underwater landslide/ density current as evidenced by a series of underwater telephone cable breaks. The last cable, 600 km south, broke 13 hours after the earthquake. Twenty-five years later, south of the earthquake site, a layer of sand was discovered on the sea floor, covering an area the size of the province of Quebec (shown above in light blue). And evidence of vast underwater landslides was found near the epicentre

http://earthnet-geonet.ca/images/communities/earthquakemap.gif


Turbidites
Turbidites ratio

  • Turbidites are formed

  • as a result of waning

  • flow.

  • A classic Bouma sequence

http://faculty.gg.uwyo.edu/heller/Sed%20Strat%20Class/SedStrat%208/bouma.jpg


Upper Carboniferous (Namurian), Ireland. Note bed tabularity.

  • Turbidite sequences can consist of 1000’s of individual beds

http://www.geoclastica.com/images/MisoaFm.jpg



Turbidites1
Turbidites tabularity.

  • The character of turbidites (e.g., the thickness and number of Bouma units varies with distance down the fan).

http://csmres.jmu.edu/geollab/fichter/SedRx/subfan.html


Knowledge of submarine fans
Knowledge of Submarine Fans tabularity.

  • Almost all of our knowledge of submarine fans comes from ancient environments and geophysics.

http://strata.geol.sc.edu/images/PosmentierKolla-elementsFan.gif


Knowledge of submarine fans1
Knowledge of Submarine Fans tabularity.

  • Fan environments are 1000’s of meters below

  • ocean, they

  • apparently have features

  • that look very much like

  • those produced by

  • surface processes.

http://strata.geol.sc.edu/images/PosmentierKolla-elementsFan.gif



Vertical column
Vertical Column fan depositional facies

  • And this is the best vertical section.


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