Chardon Dominique, Aretz M., Roques D. (2020). Reappraisal of Variscan tectonics in the southern French Massif Central. Tectonophysics, 787, p. art. 228477 [16 p.]. ISSN 0040-1951.
Titre du document
Reappraisal of Variscan tectonics in the southern French Massif Central
Tectonophysics, 2020,
787, p. art. 228477 [16 p.] ISSN 0040-1951
The comprehensive kinematic analysis of the Variscan fold nappes and associated wildflysch in the Southeastern Montagne Noire shows that the nappes were thrust northeastwardly along the Cevennes fault as a result of strike-slip-dominated sinistral transpression between 340 and 323 Ma. Macro- and map-scale recumbent folding and nappe stacking were achieved by ENE-directed, strike-parallel thrust shearing. The recumbent folds evolved into sheath folds by interplay of continued strike-parallel thrust shearing and strike-normal shortening manifested by north-verging folds that grew during wildflysch sedimentation. These results call for a tectonic reassessment of the southern side of the Variscides. The foreland basin was decoupled from the hinterland along orogen-scale sinistral fault(s) trending at a high angle to the orogenic trend, which interacted with a variety of hinterlandward thrust systems. The shift from sinistral transpression to dextral transtension along the Cevennes fault after 317 Ma accompanied the closure of the Iberian-Armorican syntax by accommodating northeastward escape and gravitational collapse of the northern limb of the syntax. These results illustrate the impact of the shift from plate convergence-controlled to escape-controlled kinematics on shear sense reversal and lower crust exhumation along long-lived strike-slip fault systems.
Plan de classement
Géologie et formations superficielles [064]
Description Géographique
FRANCE ; MASSIF CENTRAL ; MONTAGNE NOIRE ; CEVENNES
