Sutures, thrusts and nappes in the Variscan Arc of western Europe: plate tectonic implications

Abstract

Summary The Variscan Arc of western Europe, convex to the W, links the Iberian and the middle European Variscides. It is characterized by nappes and thrusts with converging vergences towards the inner part of the arc. This is illustrated by two cross-sections, one roughly E-W in northwestern Spain, the other N-S in the French Massif Central. This segment of the Variscan belt appears to be a typical collision belt whose plate tectonic evolution may be explained in the following stages: (i) consumption of a Lower Palaeozoic ocean by an intraoceanic subduction towards the NW, (ii) choking of subduction by underthrusting of continental crust beneath the oceanic lithosphere (obduction), (iii) intracontinental deformation during which the arcuate form results from the progressive impingement of a southern continental promontory (part of Africa?) into the northern Laurasian continent.