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2018-02-27 - Article/Dans un journal avec peer-review - Anglais - 11 page(s)

Cobert Corentin , Baele Jean-Marc , Boulvais Philippe, Poujol Marc, Decrée Sophie, "Petrogenesis of the Mairupt microgranite: a witness of an Uppermost Silurian magmatism in the Rocroi Inlier, Ardenne Allochton" in Comptes Rendus Geoscience

  • Edition : Elsevier Masson, Paris (France)
  • Codes CREF : Géologie (DI1411), Pétrologie (DI141A), Géologie et minéralogie (DI1410), Géochimie (DI1413), Géochronologie (DI1437)
  • Unités de recherche UMONS : Géologie fondamentale et appliquée (F401)
  • Instituts UMONS : Institut de Recherche en Science et Ingénierie des Matériaux (Matériaux)

Abstract(s) :

(Anglais) Magmatism in the Rocroi inlier (Ardenne Allochton, south-eastern Avalonia during eo-Hercynian times) consists of a swarm of bimodal dykes (diabase and/or microgranite) emplaced in Middle to Upper Cambrian siliciclastics (Revin Group). Felsic volcanites interbedded within the Upper Silurian/Lower Devonian transgressive strata on the eastern edge of the inlier were interpreted as belonging to the same magmatic event. This was subsequently invalidated by zircon U-Pb dating of the Mairupt and Grande Commune magmatic rocks, which yielded an Upper Devonian age. Here we report a reevaluation of the age of the Mairupt microgranite based on LA-ICP-MS in-situ U-Pb zircon geochronology, which yields a concordant age of 420.5 ± 2.9 Ma (Uppermost Silurian/Lowermost Devonian). This new dating restores the consistency between the different magmatic occurrences in the Rocroi inlier. The geochemical and petrographical data furthermore indicate a major crustal contribution, which fits well within the context of crust thinning of the Ardenne margin (south-eastern Avalonia) in the transtensional Rheno-Hercynian back-arc basin.

Mots-clés :
  • (Anglais) Ardenne
  • (Anglais) LA-ICP-MS U-Pb dating
  • (Anglais) Silurian magmatism
  • (Anglais) Rocroi inlier
  • (Anglais) Microgranite