Orocline triggered lithospheric delamination

Abstract

Late- to post-orogenic oroclinal bending in conjunction with thinning of the lithospheric mantle is potentially an important component of the waning stages of plate convergence in collisional orogenies. This paper addresses possible and hitherto unexplored cause-effect relationships between oroclinal bending of an originally linear orogenic belt and lithospheric thinning and delamination based on an example from the Western European Variscan Belt. We suggest that late- to post-orogenic bending of the lithosphere around a vertical axis may cause thickening and eventual detachment of the lithospheric root of orogenic belts such as the Western European Variscan Belt. The proposed hypothesis is consistent with the chronology of tectonic, metamorphic, magmatic, and hydrothermal events recorded in the Western European Variscan Belt. Moreover, this hypothesis could explain the preservation of the lithospheric root in linear orogens, like the Urals, which lack significant modification following the initial phase of “orthogonal” lithospheric thickening.