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The axis of the rift area may contain volcanic rocks, and active volcanism is a part of many, but not all, active rift systems. Major rifts occur along the central axis of most mid-ocean ridges, where new oceanic crust and lithosphere is created along a divergent boundary between two tectonic plates.
Earth: Atlantic Ocean: ≈10,000 km (6,000 mi) ≈6,000 km (4,000 mi) 7.758 km (4.821 mi) Length taken to be that of the Mid-Atlantic Ridge. (The ridge also has a secondary rift valley running its length.) The width is an average taken along the spreading ridges (Georgia–Senegal, Brazil – Bight of Benin, etc.).
Mid-ocean ridges exhibit active volcanism and seismicity. [3] The oceanic crust is in a constant state of 'renewal' at the mid-ocean ridges by the processes of seafloor spreading and plate tectonics. New magma steadily emerges onto the ocean floor and intrudes into the existing ocean crust at and near rifts along the ridge axes. The rocks ...
Continental-continental divergent/constructive boundary Oceanic divergent boundary: mid-ocean ridge (cross-section/cut-away view). In plate tectonics, a divergent boundary or divergent plate boundary (also known as a constructive boundary or an extensional boundary) is a linear feature that exists between two tectonic plates that are moving away from each other.
At this point basaltic oceanic crust and upper mantle lithosphere begins to form between the separating continental fragments. When one of the rifts opens into the existing ocean, the rift system is flooded with seawater and becomes a new sea. The Red Sea is an example of a new arm of the sea.
The Red Sea Rift is a mid-ocean ridge between two tectonic plates, the African plate and the Arabian plate. It extends from the Dead Sea Transform fault system, and ends at an intersection with the Aden Ridge and the East African Rift , forming the Afar triple junction in the Afar Depression of the Horn of Africa .
The infill of magmas in the form of dykes helps to define the shape of a volcano. A higher frequency of intrusive events along rift zones leads to elongated topographies of the affected edifices. [6] Mathematical models show how the presence of rift zones contributes to a central horizontal bulge or ridge parallel to the orientation of the ...
Some intracontinental rifts are essentially failed continental breakup axes, and some of these form triple junctions with plate boundaries. The East African Rift, for example, forms a triple junction with the Red Sea and the Gulf of Aden , both of which have progressed to the seafloor spreading stage.