The Variscan belt of Western Europe was a Palaeozoic (480-290 Ma) mountain belt formed in response to the closure of two oceans by subduction and collision of two majors continents, Laurentia-Baltica to the North and Gondwana to the South, and numerous microplates including Armorica and Avalonia (e.g., Ziegler, 1989; Franke, 2000; Matte, 2001).
A very simplified history of the southern side of this belt, on the example of the Massif Central, can be summarizing as follow. During the Cambrian-Ordovician, rifting at the north-Gondwana margin formed oceans (e.g., Ménot et al., 1988) that separate microblocks. During the Late Silurian-Devonian, oceanic/continental subduction leads to HP/UHP metamorphism (e.g., Matte, 1988; Lardeaux et al., 2001). During the Middle Devonian, limited extensional environments developed in a back-arc position while convergence continued (Faure et al., 1997; Pin and Paquette, 1997). During the Upper Devonian-Lower Carboniferous, continent-continent collision leads to crustal thickening and inverted IP metamorphism (Briand, 1978; Burg et al., 1984, 1989) by combined thrust and wrench tectonics (e.g., Burg and Matte, 1978; Brun and Burg, 1982; Ledru et al., 1994; Matte, 2001). During the Middle Carboniferous, orogen-parallel extension thinned internal zones while compression evidenced by southward thrusts was active in southern external zones (Burg et al., 1994; Faure, 1995; Roig et al., 2002). From Upper Carboniferous to Permian, postorogenic, also orogen-perpendicular, extension is widespread through out the belt (Burg et al., 1994; Faure, 1995; Faure et al., 2002; Roig and Faure, 2002). Postorogenic extension resulted in development of a lower layered crust (Rey, 1992), intense magmatism, partial melting, and crustal-scale normal faulting, leading to crustal re-equilibration (Echtler and Malavieille, 1990; Malavieille, 1993; Brun and Van Den Driessche, 1994; Lagarde et al., 1994; Ledru et al., 2001).
This geological history has not been yet recognized in the southern part of the Variscan belt which outcrops as isolated and small massifs, partly rotated and displaced during the Alpine orogeny (Figure 1). Despite post-Palaeozoic events, these massifs, that include Bohemia, Alpine crystalline massifs, Maures, Sardinia, Corsica, Tuscany, Catabria and Sicilia, seems to have experienced a common history due to their probable position at the north-Gondwana margin. These massifs may form a segment extending for ~1000 km (Matte, 2001) those the probable N-S trend may contrast with the general E-W trend of the Variscan belt. These geometrical features suggest contrasting tectonics history due to an eastern virgation of the belt similarly to the Ibero-Armorican virgation. However, correlations of lithology and tectonics between them are not well established. In this paper, we reassess the geology of the Maures massif and put forward potential correlations of lithology and tectonics with others Variscan areas, providing a new regard on the geodynamics of the southern Variscan belt.
Figure 1. Main outcrops of the Variscan belt of Western Europe
Abbreviations for Alpine External massifs: ATG = Aar-Tavetsch-Gotthard massifs, AM = Aiguilles Rouges / Mont Blanc, Be = Belledonne massif, Pe = Pelvoux massif, Ag = Argentera massif.