Abyssal fan

Abyssal fans, also known as deep-sea fans, underwater deltas, and submarine fans, are underwater structures that look like deltas formed at the end of many large rivers, such as the Nile or Mississippi Rivers. Abyssal fans are also thought of as an underwater version of alluvial fans.

Formation

Abyssal fans are formed due to underwater currents. Close to land, a river deposits sediments onto the continental shelf. By then, the sediments are still suspended in the water, with some of the larger particles sinking to the floor of the continental shelf. The further the sediments travel from the river's mouth, the less dense the particle is. Eventually, most of the particles drop to the shelf, forming thick layers of sediment. Over the years, these layers of sediment become unstable, being prone to "underwater avalanches". The flow of water coming from the river causes tones of sediment rich currents to push on the continental shelf, causing submarine canyons to be formed. The mixture of soil, rock, and clay is denser than the surrounding water, forming a current. The current is powered by gravity, therefore the denser, sediment-rich water settles to the lowest point that can be reached with only the energy that gravity provides.

Sources

• "Turbidites Hold Great Potential for Deepwater Exploration" (PDF). Baker Hughes, Inc. 2000.
• Svetlana Kostic, Gary Parker (2004). "The Response of Turbidity Currents to a Canyon-Fan Transition: Internal Hydraulic Jumps and Depositional Signatures" (PDF).

See also

• List of Oceanic Landforms