From the Upper Ordovician unconformity to the core-mantle boundary : a review of the Ordovician events in the Canigó massif, Pyrenees

We present a review of the stratigraphical, structural, geochemical, isotopic and geochronological data related to the Ordovician events in the Canigó massif, eastern Pyrenees. Voluminous felsic magmatism occurred between Mid to Late Ordovician, ranging 20m.y., in two magmatic pulses that produced several laccolithic bodies, up to ca. 2000m in thickness, which became the protoliths of the various types of the Canigó gneisses. There is also evidence of coeval basalt (future metabasites) with E-MORB affinities. Mid Ordovician uplift and erosion produced an Upper Ordovician (Sardic) unconformity with synchronous extensional faults that built propagation cleavage-free folds affecting pre-Upper Ordovician succession and caused the erosion of up to 1500m of the underlying Cambrian-Lower Ordovician succession. Early Late Ordovician synsedimentary normal faults produced significant thickness variations in the Upper Ordovician successions. Compiled data match the Ordovician evolution described in Sardinia, Mouthoumet and Montagne Noire (Occitan Domain), which differs from the evolution of neighbouring areas, such as the Iberian and Bohemian massifs, where magmatism developed earlier, in Furongian-Early Ordovician times, linked to the Toledanian unconformity. In the study area, uplift, erosion and extensional tectonics argue for a lithospheric uplift coeval with the development of felsic magmatism and metabasite with E-MORB affinities, and strongly suggests Mid to Late Ordovician plume activity beneath this segment of NW Gondwanan margin. The proposed plume would be one of a cluster of plumes impacting the Gondwana periphery that probably migrated inwards into Gondwana. Plume activity may be related to an early Paleozoic superplume event, that contributed to the birth and development of the Rheic Ocean throughout the Gondwana margin breakup.