Rheological control of accretion and covering styles of deformation and stressed state of over-subduction orogene
© V.V. Gonchar
The choice of accretion or covering types of deformation is been carried out within the plane of rheological choice of the system basement-cover-wedge, which depends on the ratio of strength and the value of tangent efforts at the line basement-cover and may be regulated by a sum of factors: the stressed state, relief of the basement and friction coefficient. This margin can be in particular characterized by pre-extreme stressed state when the limit of durability on it has not been reached or when pronounced positive gradient of durability directed to the cover is absent. In these cases orogene develops according to cover-subduction scenario. The models of development of cover and non-stationary orogene are being proposed. The first one combines progressive stages of cover deformation in case of moderately declined (1st stage) and sub-vertical (2nd stage) positions of compression axis, during which general subduction conditions do not change. Non-stationary model explains the phenomenon of "intermediate" orogenes based on the development characterized by interchange of covering-subduction and accretion types of deformation.