Abyssal plains are flat or very gently sloping areas of the deep ocean basin floor. They are among the Earth's flattest and smoothest regions and the least explored. Abyssal plains cover approximately 54% of the Earth’s surface and reach depths between 3,000 and 6,000 m (9,800 and 20,000 ft).[1] They generally lie between the foot of a continental rise and a mid-oceanic ridge.
Contents |
The abyssal plain is formed when the lower crust (sima), is melted and pushed up by the up-welling mantle, reaches the surface at mid-ocean ridges and forms new oceanic crust. This new oceanic crust is mostly basalt and has a rugged topography. The roughness of this topography is a function of the rate at which the mid-ocean ridge is spreading (the spreading rate). Magnitudes of spreading rates vary quite significantly, and are generally broken down into 3 rates (fast, medium and slow). Typical values for fast-spreading ridges are >100 mm/yr, whilst medium-spreading rates are ~60 mm/yr, and slow-spreading ridges are typically <20 mm/yr. Studies have shown that the slower the spreading rate, the rougher the new oceanic crust will be, and vice versa. It is thought this is due to faulting at the mid-ocean ridge when the new oceanic crust was formed. This oceanic crust eventually becomes overlain with sediments, producing the flat appearance.
Abyssal plains result from the blanketing of an originally uneven surface of oceanic crust by fine-grained sediments, mainly clay and silt. Much of this sediment is deposited from turbidity currents that have been channeled from the continental margins along submarine canyons down into deeper water. The remainder of the sediment comprises chiefly dust (clay particles) blown out to sea from land, and the remains of small marine plants and animals (the plankton), which sink from the upper layer of the ocean, known as Pelagic sediments. The sediment deposition rate in remote areas is estimated at two to three centimetres per thousand years. In some areas of the plains manganese nodules are common with significant varying concentrations of metals, including iron, nickel, cobalt, and copper. These nodules may provide a significant resource for future mining ventures.
Sediment-covered abyssal plains are less common in the Pacific than in other major ocean basins because sediments from turbidity currents are trapped in submarine trenches that border the Pacific Ocean.
Though the plains were assumed once to be vast, desert-like habitats, research shows that they teem with a wide variety of microbial life.[2][1]
Please help develop this page
This page was created, but so far, little content has been added. Everyone is invited to help expand and create educational content for Wikiversity. If you need help learning how to add content, see the editing tutorial and the MediaWiki syntax reference. To help you get started with content, we have automatically added references below to other Wikimedia Foundation projects. This will help you find materials such as information, media and quotations on which to base the development of "Abyssal plain" as an educational resource. However, please do not simply copy-and-paste large chunks from other projects. You can also use the links in the blue box to help you classify this page by subject, educational level and resource type. |
|
|
|
Wikis
Quiz
Facts
Map
Search
