Comparative geochemical study on Furongian–earliest Ordovician (Toledanian) and Ordovician (Sardic) felsic magmatic events in south-western Europe: underplating of hot mafic magmas linked to the opening of the Rheic Ocean

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Álvaro, J.J. and Sánchez García, Teresa and Puddu, Claudia and Casas Tuset, Josep María and Díez Montes, Alejandro and Liesa Torre Marín, Montserrat and Oggiano, Giacomo (2020) Comparative geochemical study on Furongian–earliest Ordovician (Toledanian) and Ordovician (Sardic) felsic magmatic events in south-western Europe: underplating of hot mafic magmas linked to the opening of the Rheic Ocean. Solid Earth, 11 (6). pp. 2377-2409. ISSN 1869-9529

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Official URL: https://se.copernicus.org/articles/11/2377/2020/



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.


Item Type:Article
Subjects:Sciences > Geology > Geochemistry
Sciences > Geology > Petrology
ID Code:63604
Deposited On:15 Jan 2021 17:35
Last Modified:18 Jan 2021 10:41

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