Abstract
Abstract. A geochemical comparison of early Palaeozoic felsic magmatic episodes throughout the south-western European margin of Gondwana is made and includes (i) Furongian–Early Ordovician (Toledanian) activities recorded in the Central Iberian and Galicia–Trás-os-Montes zones of the Iberian Massif, and (ii) Early–Late Ordovician (Sardic) activities in the Eastern Pyrenees, Occitan Domain (Albigeois, Montagne Noire and Mouthoumet massifs) and Sardinia. Both phases are related to uplift and denudation of an inherited palaeorelief, and stratigraphically preserved as distinct angular discordances and paraconformities involving gaps of up to 22 million years. The geochemical features of the predominantly felsic Toledanian and Sardic activities point to a predominance of magmatic byproducts derived from the melting of metasedimentary rocks, rich in SiO2 and K2O and with a peraluminous character. Zr ∕ TiO2, Zr ∕ Nb, Nb ∕ Y and Zr vs. Ga ∕ Al ratios, and rare-earth element (REE) and εNd(t) values suggest the contemporaneity, for both phases, of two geochemical scenarios characterized by arc and extensional features evolving to distinct extensional and rifting conditions associated with the final outpouring of mafic tholeiite-dominant lava flows. The Toledanian and Sardic magmatic phases are linked to neither metamorphism nor penetrative deformation; on the contrary, their unconformities are associated with foliation-free open folds subsequently affected by the Variscan deformation. The geochemical and structural framework precludes subduction-generated melts reaching the crust in a magmatic arc-to-back-arc setting and favours partial melting of sediments and/or granitoids in the lower continental crust triggered by the underplating of hot mafic magmas related to the opening of the Rheic Ocean.
Highlights
A succession of early Palaeozoic felsic magmatic episodes, ranging in age from Furongian to Late Ordovician, are widespread along the south-western European margin of Gondwana
All subgroups display similar chondrite-normalized rare-earth element (REE) patterns (Fig. 7), with an enrichment in light rare-earth element (LREE) relative to heavy rareearth element (HREE), which should indicate the involvement of crustal materials in their parental magmas
For the Eastern Pyrenees, we find the same situation as in the Central Iberian Zone, with a magmatic evolution toward A-type granite characteristics, indicating more extensional geotectonic environments
Summary
A succession of early Palaeozoic felsic magmatic episodes, ranging in age from Furongian (formerly “late Cambrian”) to Late Ordovician, are widespread along the south-western European margin of Gondwana. Magmatic pulses are characterized by preferential development in different palaeogeographic areas and linked to the development of stratigraphic unconformities, but they are related to neither metamorphism nor penetrative deformation (Gutiérrez Marco et al, 2002; Montero et al, 2007). Álvaro et al.: Early Palaeozoic magmatic felsic events in SW Europe
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
