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- Title
Evidence for pre-orogenic, Early Devonian rifting in the Variscan belt: stratigraphy and structure of the Palaeozoic cover of the Mauges Unit (Upper Allochthon, Armorican massif, France).
- Authors
Ducassou, Céline; Ballèvre, Michel; Lardeux, Hubert; Robin, Cécile
- Abstract
The Palaeozoic sediments from the Mauges Unit (Armorican Massif, France) are the best-preserved pre-orogenic sequences belonging to the Upper Allochthon. Two coherent sequences are identified. The southern unit (Châteaupanne Unit) represents the cover of the Proterozoic basement and consists of Ordovician sediments unconformably overlain by Emsian carbonates followed by Emsian to earliest Eifelian immature sandstones. The northern unit (Tombeau Leclerc Unit) consists of an Hirnantian to Emsian condensed sequence, in reverse position, that has been thrust over the southern unit. The Devonian unconformity is interpreted as evidence for an Early Devonian extension, recorded by normal faults affecting both the Early Devonian limestones and the underlying Ordovician series. This crustal extension, recorded here for the first time, is possibly related to the opening of a back-arc basin (Saint-Georges-sur-Loire) associated with the subduction of an ocean located further south (Galicia-Brittany-Massif Central Ocean).
- Subjects
ARMORICAN Massif (France); FRANCE; DEVONIAN stratigraphic geology; ORDOVICIAN paleoecology; OROGENIC belts; BACK-arc basins; CARBONATES; SEDIMENTARY rocks
- Publication
International Journal of Earth Sciences, 2011, Vol 100, Issue 7, p1451
- ISSN
1437-3254
- Publication type
Article
- DOI
10.1007/s00531-010-0605-3