| Abyssal Plain |
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| CATEGORIES ABOUT ABYSSAL PLAIN | |
| aquatic ecology | |
| oceanography | |
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The abyssal plain is formed when the lower crust ( Sima ), 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 >100mm/yr, whilst medium-spreading rates are ~60mm/yr, and slow-spreading ridges are typically <20mm/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 Sediment s, mainly Clay and Silt . Much of this sediment is deposited from Turbidity Current s 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 sediment. 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, Iron , Nickel , Cobalt , and Copper . These nodules provide a sigificant 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 Trench es that border the Pacific Ocean. LIST OF ABYSSAL PLAINS ;Atlantic ocean
;Indian ocean:
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