Décollement

A shear indicated in geology a disorder which extends parallel to or intersects the layer coatings in a very shallow angle. Shearing can be extensional ( stretching ) or kontraktional ( shortening). The reason can be described as a shearing mostly horizontal offset of rock stacks along a surface.

Prerequisite

Prerequisite for shearing is usually incompetent so easy deformable support ( often a water-saturated layer of clay or other minerals such as evaporites deformable ) on which the upper portion of a layer packet with respect to the lower part moves. This easily deformable layer is also referred to as Abscherungsfläche. Often a shearing occurred gravitationally (caused by gravity ) in a slightly inclined rock strata.

Deformation

Shears are usually present together with folds and thrust. Are the shearing großdimensional, one also speaks of Abscherungdecken. However, these have been moved to a rule is less than a thrust sheet, and therefore are usually still on its original base. The transitions between the two forms are fluid.

In special cases the displacement of shearing is several tens of kilometers, such as in metamorphic core complexes. The Abscherungsfläche is then often referred to the English / French term décollement or Detachment.

A shearing may occur in large-scale tectonic extension of an area as well as in large-scale tectonic narrowing.