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An ophiolite is a section of Earth's oceanic crust and the underlying upper mantle that has been uplifted and exposed, and often emplaced onto continental crustal rocks. The Greek word ὄφις, ophis (snake) is found in the name of ophiolites, because of the superficial texture of some of them. Serpentinite especially evokes a snakeskin.
Ophiolites are sequences of mafic to ultramafic rock generally believed to represent ancient oceanic lithosphere.They are distributed all across the world being all of them located at present or past orogenic belts, sites of mountain building processes.
Marine sediment, or ocean sediment, or seafloor sediment, are deposits of insoluble particles that have accumulated on the seafloor.These particles either have their origins in soil and rocks and have been transported from the land to the sea, mainly by rivers but also by dust carried by wind and by the flow of glaciers into the sea, or they are biogenic deposits from marine organisms or from ...
The exact origins of the rocks found in the ophiolite are a matter of debate; some geologists hypothesize that the rock primarily consists of mid-ocean lithosphere, while others assert different ideas related to island arc terranes associated with the Nevadan orogeny.
Polymetallic nodules are found in both shallow (e.g. the Baltic Sea [7]) and deeper waters (e.g. the central Pacific), even in lakes, [8] and are thought to have been a feature of the seas and oceans at least since the deep oceans were oxygenated in the Ediacaran period over 540 million years ago.
The oceanic crust displays a pattern of magnetic lines, parallel to the ocean ridges, frozen in the basalt. A symmetrical pattern of positive and negative magnetic lines emanates from the mid-ocean ridge. [24] New rock is formed by magma at the mid-ocean ridges, and the ocean floor spreads out from this point.
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An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between 3,000 and 6,000 metres (9,800 and 19,700 ft).Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth's surface.