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Schematic diagram showing the physical processes inside the Earth that lead to the generation of magma. Partial melting begins above the fusion point. Map showing approximate location of many current hotspots and the relationship to current tectonic plates and their boundaries and movement vectors
Plate tectonics (from Latin tectonicus, from Ancient Greek τεκτονικός (tektonikós) 'pertaining to building') [1] is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago.
This paradoxically results in divergence which was only incorporated in the theory of plate tectonics in 1970, but still results in net destruction when summed over major plate boundaries. [2] Divergent boundaries are areas where plates move away from each other, forming either mid-ocean ridges or rift valleys. These are also known as ...
The relative movement of the plates typically ranges from zero to 10 cm annually. Faults tend to be geologically active, experiencing earthquakes, volcanic activity, mountain-building, and oceanic trench formation. Tectonic plates are composed of the oceanic lithosphere and the thicker continental lithosphere, each topped by its own kind of crust.
A tectonic phase or deformation phase is in structural geology and petrology a phase in which tectonic movement or metamorphism took place. Tectonic phases can be extensional or compressional in nature. When numerous subsequent compressional tectonic phases share the same geodynamic cause (usually some plate tectonic mechanism) this is called ...
Extensional tectonics is associated with the stretching and thinning of the crust or the lithosphere.This type of tectonics is found at divergent plate boundaries, in continental rifts, during and after a period of continental collision caused by the lateral spreading of the thickened crust formed, at releasing bends in strike-slip faults, in back-arc basins, and on the continental end of ...
A schematic evolutionary diagram showing the impact of a mantle plume on the early lithosphere (dark blue) and surface proto-crust (brown). This initiated subduction and subsequent global plate tectonics within a previously unseparated lithosphere that had no lateral surface movement.Modified from [17]
Diagram showing a transform fault with two plates moving in opposite directions Transform fault (the red lines). A transform fault or transform boundary, is a fault along a plate boundary where the motion is predominantly horizontal. [1]