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Rifting may lead to continental breakup and formation of oceanic basins. Successful rifting leads to seafloor spreading along a mid-oceanic ridge and a set of conjugate margins separated by an oceanic basin. [14] Rifting may be active, and controlled by mantle convection. It may also be passive, and driven by far-field tectonic forces that ...
A three-step process [4] has been proposed for the mechanism of rifting. First, a thermal anomaly developed in the mantle in the earliest stages of rifting, causing the rise of the asthenosphere and the thinning of the subcrustal continental lithosphere. There have been several mechanisms proposed to achieve this, such as convective thermal ...
Seafloor spreading helps explain continental drift in the theory of plate tectonics. When oceanic plates diverge , tensional stress causes fractures to occur in the lithosphere . The motivating force for seafloor spreading ridges is tectonic plate slab pull at subduction zones , rather than magma pressure, although there is typically ...
Continental rifting forms new ocean basins. Eventually the continental rift forms a mid-ocean ridge and the locus of extension moves away from the continent-ocean boundary. The transition between the continental and oceanic lithosphere that was originally formed by rifting is known as a passive margin.
The addition of these magmatic materials usually contributes to the further rifting of the slope, in addition to generating fissure eruptions from those dykes that reach the surface. It is the grouping of these fissures, and the dykes that feed them, that serves to delineate where and whether a rift zone is to be defined. [ 2 ]
Passive rifting, unlike active rifting, occurs principally by extensional tectonic forces as opposed to magmatic forces originating from convection cells or mantle plumes. Isostatic forces allow mantle material to rise under the thinning lithosphere. Subsidence and sedimentation occur during both the initial rifting stage and the post rifting ...
This rifting almost tore apart the African continent but instead formed a complex system of extensional, wrench and pull-apart basins. [ 3 ] [ 4 ] Such basins can be found from Nigeria and Cameroon on the Atlantic, east into Chad and the Central African Republic, through Sudan to Kenya on the Indian Ocean and north of Lake Chad extending into ...
Two rifting episodes created the Canadian Arctic Rift System. The first is referred to as the Boreal Rifting Episode which followed compression and exposure brought on by the Ellesmerian orogeny. The second is referred to as the Eurekan Rifting Episode and created most of the structures that comprise the Canadian Arctic Rift System.