![]() Along the axis of the rift the position, and in some cases the polarity (the dip direction), of the main rift bounding fault changes from segment to segment. ![]() Areas of thick colder lithosphere, such as the Baikal Rift have segment lengths in excess of 80 km, while in areas of warmer thin lithosphere, segment lengths may be less than 30 km. Segment lengths vary between rifts, depending on the elastic thickness of the lithosphere. The individual rift segments have a dominantly half-graben geometry, controlled by a single basin-bounding fault. ![]() Most rifts consist of a series of separate segments that together form the linear zone characteristic of rifts. Two of these evolve to the point of seafloor spreading, while the third ultimately fails, becoming an aulacogen. Typically the transition from rifting to spreading develops at a triple junction where three converging rifts meet over a hotspot. 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.įailed rifts are the result of continental rifting that failed to continue to the point of break-up. The axis of the rift area may contain volcanic rocks, and active volcanism is a part of many, but not all, active rift systems. Where rifts remain above sea level they form a rift valley, which may be filled by water forming a rift lake. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben with normal faulting and rift-flank uplifts mainly on one side. In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Gulf of Suez Rift showing main extensional faults
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