Geodynamic evolution of a Cadomian arc region:: the northern Ossa-Morena zone, Iberian massif

Ductile deformation and polyphase metamorphism in the Ossa-Morena zone of the Iberian massif are related to two major tectonothermal episodes of Cadomian (late Neoproterozoic to early Cambrian) and Variscan age (middle to late Paleozoic). The available petrological, structural and geochronological data suggest that a number of tectono-metamorphic and magmatic episodes occurred during the 620-480 Ma interval that would comprise a complete Cadomian Wilson cycle. The geodynamic scenario was that of air Andean-type continental margin. An evolutionary model is presented for this orogeny comprising stages of volcanic arc generation, crustal thickening, back-are extension, tectonic inversion and cratonization. A correlation with comparable areas from pre-Mesozoic massifs elsewhere in Europe is proposed, in particular with the Armorican massif of northern France. (C) 2002 Elsevier Science B.V. All rights reserved.