(a) Orogens, foredeeps and foreland basins differentiated on the basis of the related subduction; namely systems with orogen advance vector the same as that of mantle flow (west-dipping, left-hand-side diagram) and systems with orogen advance vector opposing that of mantle flow (east or NE-dipping, right-hand-side diagram; Doglioni 1993b). Foredeeps and thick-skin tectonic regions develop at three sides of these two systems: (1) at the front of pro-wedge of the west-dipping subduction system; (2) at the front of pro-wedge of the east or NE-dipping subduction system; and (3) at the front of its retro-wedge. Orogen advance vector is indicated by small arrow and mantle flow is shown by large arrow. Left side shows retreating subduction zone; right side shows advancing subduction zone. (b) Main differences between orogens whose advance vector is the same as that of mantle flow (west-dipping) and orogens whose advance vector opposes that of mantle flow (east or NE-dipping) shown in more detail, using the same geographic orientations as those in (a) (Doglioni 1993b). Orogens with advance vector the same as mantle flow are characterized by low structural and morphological elevation. The rocks occurring at the surface indicate relatively shallow burial. The tangent to the anticlines of the accretionary wedge descends orogen-wards. The depocentre of the deep foredeep basin is within the accretionary wedge. Orogens with advance vector opposite to mantle flow are characterized by high structural and morphological elevation. The rocks occurring at the surface indicate relatively deep burial. The tangent to the anticlines of the accretionary wedge ascends orogen-wards. The depocentre of the shallow foredeep basin is in front of the accretionary wedge. The curves on the right side represent a possible elevation history of a reference point, which was originally located in the foredeep, during development of the respective orogen. The upper curve shows a reference point affected by the migration of three main tectonic events, A, B and C. The foredeep subsidence, A, is driven by roll-back of the subduction hinge and complicated by smaller-scale uplift events associated with individual thrust sheet accretion pulses. The subsidence can be as high as 1.6 mm a⁻¹. It is followed by an uplift, B, controlled by mantle wedging at the top of the subduction hinge, shear and transition from shortening to extension. Segment C of the curves denotes the back-arc basin subsidence. The lower curve shows a reference point affected by migration of the two main tectonic events, D and E. The subsidence, D, is controlled by either thrust loading affecting the foredeep or localized subsidence controlled by out-of-sequence thrusts. The characteristic subsidence is about 0.3 mm a⁻¹. The uplift, E, is controlled by folding.

Conceptual interpretation of the two end-member convergence scenarios (Waschbusch & Beaumont 1996). (a) Scenario without subduction zone retreat requires space for crustal accretion to be created by retro-thrusting. (b) Scenario with subduction zone retreat manages to create space for crustal accretion without a need for retro-thrusting.

(a) Example of an orogen opposing mantle flow represented by schematic profile through the Swiss–Italian Western Alps from the Mont Tendre in Jura Mountains to the Val Sesia in the Ivrea area (Escher & Beaumont 1997). Convergence drove subduction of the European and Brianconnais lithospheres. The nappe stacking and other deformation events took place within the upper part of the down-going continental crust, while the lower crust has been interpreted as subducting passively together with lithospheric mantle. (b) Example of an orogen following mantle flow represented by balanced cross section through the Western Carpathians accretionary wedge (Nemčok et al. 2006). Convergence drove subduction of the West European lithosphere. Accretionary wedge development and other deformation events took part within upper part of the down-going continental crust, while the lower crust is assumed to be subducting passively together with lithospheric mantle.

Regional balanced cross section through the Eastern Cordillera, Colombia with earthquake hypocentres/foci (circles) projected (Ingeominas 2009; Tesón et al. 2013).

Structural map and line-drawing interpretation of seismic sections showing variation in structural style in the Broad Fourteens basin as a consequence of development of the Zechstein salt horizon (modified from Nalpas et al. 1995).

External and internal factors controlling orogenic deformation (Ellis & Beaumont 1999). (a) Velocity conditions contain pro-mantle lithosphere converging and subducting at uniform velocity v_p and retro-mantle converging at uniform velocity v_R. Mantle subduction point S moves with velocity v_S. Its positive v. negative values represent subduction zone advance v. retreat. (b) Internal model properties include rheologies of deforming layers, detachment horizons, intrusions and inherited strength contrasts. (c) External factors include erosion and deposition modifying the load distribution. Thickened crust grows against increasing gravity resistance because of its increasing potential energy. Loads and thickened layers are flexurally compensated by paired broken elastic beams below the model layer.