Abstract

The French Massif Central and Massif Armoricain belong to three tectonic and paleogeographic domains of the Medio-Europa Variscan Orogen. The entire Massif Central and southern part of the Massif Armoricain belong to the North Gondwana margin, the Central Armorican Domain is a part of Armorica microcontinent and the Léon Domain is a piece of another microcontinent. The N. Gondwana margin and Léon Domain are made of a stack of metamorphic nappes, conversely, the Central Armorican Domain consists of a Proterozoic basement built up by the Neoproterozoic Cadomian orogeny and a Paleozoic sedimentary cover weakly deformed by upright folds related to wrenching. The architecture of the North Gondwana margin results of three main tectonic-metamorphic events that follow an early Late Silurian (ca 415 Ma) high-pressure metamorphism whose associated structures are poorly documented. The Early Devonian D1 event is responsible for top-to-the-SW nappes coeval with migmatization and exhumation of high-pressure rocks around 385-380 Ma. The Late Devonian-Early Carboniferous D2 event is a top-to-the-NW shearing coeval with an intermediate pressure-temperature metamorphism dated around 360-350 Ma. The Visean D3 event is a top-to-the-south shearing widespread in the south Massif Central whereas in north Massif Central, D3 corresponds to the onset of synorogenic extension. The Variscan Belt is also characterized by a widespread magmatism. The Early-Middle Devonian calc-alkaline magmatism is related to the southward subduction of the Rheic Ocean. The Carboniferous magmatic events are the crustal melting response of D2 and D3 tectonic events. Late Visean, Namurian and Westphalian magmatic stages are coeval with extensional tectonics controlled by NW-SE stretching. These structural, metamorphic and magmatic events are replaced in a geodynamic evolution model involving two cycles of microcontinent drifting, rewelding and continental collision.