In-situ U–Pb zircon ages for Early Ordovician magmatism in the eastern Pyrenees, France: the Canigou orthogneisses

Abstract

U–Pb age determinations with an ion probe on zircons within orthogneisses from the Canigou Massif, eastern Pyrenees, give an emplacement age for their granitic protolith of 475±10 Ma (Arenigian). This invalidates the previous interpretation of basement-cover relationships between the orthogneisses and the overlying Lower Cambrian Canaveilles metasedimentary series, and corroborates the intrusive character of the orthogneisses, which is further supported by field evidence. The data also define two groups of inherited zircons (Paleo/Meso-Proterozoic and Cadomian) in addition to partial lead loss during the Hercynian Late Carboniferous high temperature–low pressure metamorphic event. These results are in agreement with ages reported from other orthogneissic bodies across the entire Variscan chain of western Europe, and indicate the existence of a widespread Cambro-Ordovician magmatic event.