Abyssal fan: Difference between revisions

Content deleted Content added

Inline

Revision as of 01:29, 8 October 2009

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 (or submarine) fans are formed due to turbidites . Tubidites are essentially gravity driven underwater avalanches. As sediment is deposited on the continental slope , the steepest part of the ocean, it is prone to sliding down onto the continental rise due to gravity. Once the weight of the sediment accumulating gets to be too much, the pile of sediment will slide down all at once falling down onto the continental rise. After thousands of years of turbidite deposition on the rise, a fan forms towards the top of the continental rise. This fan is similar to an alluvial fan found on land near mountains and rivers. The abyssal fan has characteristics of a standard turbidite. The Bouma Sequence is used to describe the nature and sediment patterns of a turbidite.

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).

@@ Line 2: / Line 2: @@
 == 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 [[turbidity current|sediment rich currents]] to push on the continental shelf, causing [[submarine canyon|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.
+Abyssal (or submarine) fans are formed due to [[turbidites]] .  Tubidites are essentially gravity driven underwater avalanches.  As sediment is deposited on the [[continental slope]] , the steepest part of the ocean, it is prone to sliding down onto the continental rise due to gravity.  Once the weight of the sediment accumulating gets to be too much, the pile of sediment will slide down all at once falling down onto the continental rise.  After thousands of years of turbidite deposition on the rise, a fan forms towards the top of the continental rise.  This fan is similar to an [[alluvial fan]] found on land near mountains and rivers.  The abyssal fan has characteristics of a standard turbidite.  The Bouma Sequence is used to describe the nature and sediment patterns of a turbidite.
 == Sources ==

Revision as of 01:29, 8 October 2009

Formation

Sources

See also