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Fault blocks are very large blocks of rock, sometimes hundreds of kilometres in extent, created by tectonic and localized stresses in Earth's crust. Large areas of bedrock are broken up into blocks by faults. Blocks are characterized by relatively uniform lithology. The largest of these fault blocks are called crustal blocks.
A fault trace or fault line is a place where the fault can be seen or mapped on the surface. A fault trace is also the line commonly plotted on geologic maps to represent a fault. [3] [4] A fault zone is a cluster of parallel faults. [5] [6] However, the term is also used for the zone of crushed rock along a single fault. [7]
Tilted block faulting, also called rotational block faulting, is a mode of structural evolution in extensional tectonic events, a result of tectonic plates stretching apart. [ 1 ] [ 2 ] When the upper lithospheric crust experiences extensional pressures, the brittle crust fractures, creating detachment faults . [ 3 ]
This results in block faulting, where the blocks of rock between the normal faults either subside, uplift, or tilt. The movement of these blocks results in the alternating valleys and mountains. As the crust thins, it also allows heat from the mantle to more easily melt rock and form magma, resulting in increased volcanic activity. [3]
A graben is a section of crust that has lowered relative to the blocks on either side, which is a result of its bounding faults dipping towards each other. [2] The plural of graben can be either graben or grabens. Graben form low-lying features such as basins and rift valleys. [1] [2] They can be very long relative to their width.
Dip is defined as the angle of the fault relative to the surface of the earth, which indicates the plane on which slip will occur. Lastly, in any non-vertical fault, the block above the fault is called the hanging wall, while the blockbelow the fault is called the footwall. [4] Normal and reverse dip-slip faults with labeled hanging wall and ...
When a fault block is raised or tilted, a block mountain can result. [17] Higher blocks are called horsts, and troughs are called grabens. A spreading apart of the surface causes tensional forces. When the tensional forces are strong enough to cause a plate to split apart, it does so such that a center block drops down relative to its flanking ...
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 [1] and at strike-slip systems parallel to oblique subduction zones. [2]