An autochthon in
structural geology
Structural geology is the study of the three-dimensional distribution of rock units with respect to their deformational histories. The primary goal of structural geology is to use measurements of present-day rock geometries to uncover informati ...
is a large block or mass of rock which is in the place of its original formation relative to its
basement
A basement is any Storey, floor of a building that is not above the grade plane. Especially in residential buildings, it often is used as a utility space for a building, where such items as the Furnace (house heating), furnace, water heating, ...
or foundation rock. The word is derived from Greek: ''autos'' means self, and ''chthon'' means earth.
It can be described as rooted to its basement rock as opposed to an
allochthon
upright=1.6, Schematic overview of a thrust system. The hanging wall block is (when it has reasonable proportions) called a window. A klippe is a solitary outcrop of the nappe in the middle of autochthonous material.
An allochthon, or an alloc ...
ous block or
nappe
In geology, a nappe or thrust sheet is a large sheetlike body of rock that has been moved more than or above a thrust fault from its original position. Nappes form in compressional tectonic settings like continental collision zones or on the ...
which has been relocated from its site of formation.
[ ] Autochthonous
sediment
Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of ...
is sediment found at or very close to its site of deposition.
image:thrust system en.jpg, upright=1.6, Schematic overview of a thrust system. The hanging wall block is (when it has reasonable proportions) called a
nappe
In geology, a nappe or thrust sheet is a large sheetlike body of rock that has been moved more than or above a thrust fault from its original position. Nappes form in compressional tectonic settings like continental collision zones or on the ...
which overlays the autochthonous (unrelocated) material. A hole in the nappe which exposes the underlying autochthonous material is called a
window
A window is an opening in a wall, door, roof, or vehicle that allows the exchange of light and may also allow the passage of sound and sometimes air. Modern windows are usually glazed or covered in some other transparent or translucent ma ...
. A klippe is a solitary outcrop of the nappe in the middle of autochthonous material.
While an autochthon may have experienced some minor shifting, an allochthonous block will have moved at least a few kilometres.
[Marko, F., Jacko, S., 1999]
''Structural geology (General and systematic).''
Vydavateľstvo Harlequin, Košice, p. 81 - 93 If an overlying allochthon has an opening or hole which exposes the underlying autochthonous material, the hole is called a
window
A window is an opening in a wall, door, roof, or vehicle that allows the exchange of light and may also allow the passage of sound and sometimes air. Modern windows are usually glazed or covered in some other transparent or translucent ma ...
or fenster.
See also
*
Tectonics
Tectonics ( via Latin ) are the processes that result in the structure and properties of the Earth's crust and its evolution through time. The field of ''planetary tectonics'' extends the concept to other planets and moons.
These processes ...
References
External links
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Structural geology
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