There are various mechanisms of rock melting that can be achieved in different stress regimes dependent on the tectonics of the region. Magmatism is the process by which rock is heated deep in the earth’s mantle or crust via different types of melting, forming magma, liquid or semi-liquid molten rock which buoyantly rises towards the earth’s surface to either be intruded as an igneous body or extruded as lava. Mechanisms of magmatism in areas of strike-slip tectonics Examples include the Dead Sea Transform in the Middle East and the San Andreas Fault in California. However, there are certain scenarios in which strike-slip movement and its associated features can induce magmatism. In most cases, strike-slip faults only play a role in the migration of magma along their planes of weakness, rather than being directly responsible for the origin of magmatism. It is more frequently associated with extensional and compressional regimes, which give rise to normal and reverse/thrust faults, respectively. Typically, magmatism is not commonly associated with strike-slip regimes. There are different kinds of strike-slip fault and settings in which they occur: continental and oceanic transform faults form in areas of plate divergence and sea floor spreading, strain-partitioned strike-slip faults can occur in both oceanic and continental crust at zones of oblique subduction.Ī simple diagram demonstrating the structure of strike-slip faults and their movement. Depending on the movement of the fault blocks relative to the fault plane, strike-slip faults can be classified as either sinistral (left-lateral displacement) or dextral (right-lateral displacement). Strike-slip faults are commonly almost vertically inclined faults, where the main displacement and slip is in the horizontal direction, parallel to the strike of the fault. Both magma and strike-slip faults coexist and affect one another. In contrast, magmatism can also directly impact on strike-slip faults by determining fault formation, propagation and slip. They can either induce magmatism, act as a conduit to magmatism and magmatic flow, or block magmatic flow. Strike-slip faults have a direct effect on magmatism. If fault slip outpaces erosion, the part of the drainage past the fault may become entirely separated from its catchment, becoming a beheaded channel.Magmatism along strike-slip faults is the process of rock melting, magma ascent and emplacement, associated with the tectonics and geometry of various strike-slip settings, most commonly occurring along transform boundaries at mid-ocean ridge spreading centres and at strike-slip systems parallel to oblique subduction zones. Deflected channels may form where erosion happens fast enough relative to fault slip for a stream to turn course and flow along the fault for the distance of offset. When filled with water, these depressions are called sag ponds. When such a scarp blocks off a drainage, it is called a shutter ridge.Where two topographic lows are moved next to each other, they form a tectonic furrow. Scarps related to strike-slip faulting generally form because the fault moves an area of higher topography up against a lower area. Note that this term simply describes the shape of the land, not the process by which that shape was created. Many distinctive features form as a result of strike-slip fault activity.Ī scarp is a sharp break in topography. Understanding seismic hazard from strike-slip fault earthquakes requires recognition of how active strike-slip faults affect landscapes. An arc-arc transform joins a pair of offset subduction zones.Ĭontinental transforms, such as the Alpine fault in New Zealand and the San Andreas in California, mimic their oceanic counterparts in connecting other types of plate boundaries. A ridge-arc transform is located on the side of a plate with one edge being subducted beneath an arc and the other growing at a mid-ocean ridge. A ridge-ridge transform, such as the one pictured above, connects two mid-ocean ridges. Transform faults come in three varieties, defined by the types of plate boundaries connected to them. A bathymetric step remains, however, and this area is called a fracture zone. Beyond the spreading centers, the fault is not active because both sides move in the same direction. Fault slip is sinistral, opposite of the apparent dextral offset of the ridges. This map shows a pair of spreading centers separated by a transform fault. Transform faults are plate boundary faults, and are tens to hundreds of kilometers long.
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