In geology , tectonics (from Greek τεκτονικός tektonikós, “relating to architecture”) describes the theory of the structure of the earth's crust and the small and large-scale movements that take place in it. Structures and movements in the upper part of the earth's mantle ( lithosphere ) are also a field of consideration for tectonics. The more global aspects and theories of earth development are called geotectonics .
On the other hand, tectonics describes the structure of the earth's crust and the geodynamic movements themselves, in particular the displacement of the continental plates and their effects ( plate tectonics ).
Types of tectonic processes
The geologist deduces the direction, strength, duration and time of these movements from the faults and folding of rock packages observed in the terrain as well as the characteristics of the rocks concerned , such as fissures , foliation and degree of metamorphosis .
According to the predominant geological structures, a distinction can be made:
- Fault or fracture tectonics : near the surface of the earth, lateral pressure, but also pressure relief, lead to the breaking of the rock layers and shifting of the rock packages against each other, along partially open joints, crevices, crevices and faults. As a rule, the rocks do not fold thoroughly. Examples are the formation of tectonic trenches and clumps . Fracture tectonics is also often involved in the sinking of sedimentary basins and the lateral displacement of areas of the earth's crust against each other. A sudden reduction in tension in the fault zones involved creates an earthquake .
- Fold tectonics : The exact time at which the folding begins depends on the nature of the rocks concerned. Under certain conditions, wrinkles appear even at a shallow depth under the surface of the earth. In most cases, however, the rocks begin to deform plastically ( ductility ) at greater depths, i.e. at higher pressures and temperatures, and are then folded. The formation of open crevices is no longer possible, and the movement of the rock packets against each other no longer only takes place at faults, but primarily through internal deformation and movement in regional shear zones . The rocks are subject to a transformation that creates metamorphic rocks . This transformation can affect all rocks in a region ( regional metamorphosis ).
- Thrust tectonics : Under suitable conditions, folded and unfolded rocks can thrust one another as tectonic nappes . Rock packages of large dimensions can be transported over long distances. The construction of these thrust bodies can be very complex.
- Mountain formation , fold mountains
- Structural geology
- Granite tectonics , salt tectonics
- Fault (geology)
- Extension (geology)