Monazite U-Th/Pb chemical dating of the Early Carboniferous syn-kinematic MP/MT metamorphism in the Variscan French Massif Central

Jérémie Melleton (1, 2) , Michel Faure (2) , Alain Cocherie (1)

1 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)
2 ISTO - Institut des Sciences de la Terre d'Orléans

U-Th-Pb geochronology on monazite using Electron Probe Micro Analyser, constrained by structural and textural observations, has been performed on four samples from the Limousin area (northwest part of the French Massif Central) in order to date the syn-kinematic MP/MT metamorphism related to the top-to-the-NW shearing that deformed the stack of nappes in this zone of the Variscan belt. All the analyzed samples lead to a mean age at 360 ± 4 Ma. The close range of ages obtained during this study (360 Ma) and with the previous 40Ar-39Ar ones (360-350 Ma) suggests fast processes of cooling and exhumation during the Early Carboniferous in internal zones of the Variscan belt. The geodynamic significance of this Early Carboniferous event is discussed at the scale of the Ibero-Armorican orocline.

Keywords: Monazite U-Th/Pb chemical dating; French Massif Central; Limousin; Variscan belt.; Variscan belt

Domains: Sciences of the Universe [physics]; Earth Sciences; Applied geology

Jérémie Melleton, Michel Faure, Alain Cocherie. Monazite U-Th/Pb chemical dating of the Early Carboniferous syn-kinematic MP/MT metamorphism in the Variscan French Massif Central. Bulletin de la Société Géologique de France, 2009, 180 (3), pp.283-292. ⟨10.2113/gssgfbull.180.3.283⟩. ⟨insu-00411227⟩