The unique Cambro-Ordovician silicic large igneous province of NW Gondwana: Catastrophic melting of a thinned crust Rodriguez Almodóvar, Carmen Castro, Antonio Gómez Frutos, Daniel Gutiérrez Alonso, Gabriel Pereira, M. Francisco Fernández, Carlos Cambro-Ordovician magmatism Ollo de Sapo Formation Data-analysis Geochemical modelling Extensive crustal melting This work was supported through the Spanish Research Agency (AEI) Grant Nº PGC2018-096534-B-I00 (Proyecto IBERCRUST). M.F. P. acknowledges the Portuguese Foundation for Science and Technology (FCT) project UIDB/04683/2020, Instituto de Ciências da Terra. This manuscript was benefit from valuable suggestions from Marcos García-Arias and two anonymous reviewers. Cambro–Ordovician silicic magmatism in the Central Iberian Zone of the Iberian Massif (Ollo de Sapo Formation, OSF) constitutes a voluminous and geochemically atypical magmatic event that formed preceding the breakup of the northern margin of Gondwana. To date, and due to uncommon geochemical signatures, such as a high Fe, Mg content compared to anatectic melts and the departing from the calc-alkaline trends, the origin of such magmatic event is not fully understood. Herein, we report a data-analysis of geochemistry linking magmas and source compositions. The analysis of the combined data from multiple studies ascribes the geochemistry of the OSF rocks to a combination of extensive melting of Ediacaran metasiliciclastic rocks and a Ca-rich component. It is hypothesized that fluids released by crystallization of mafic magmas contributed to partial melting of a thick metasedimentary pile represented by Ediacaran siliciclastic rocks. Such melting event gave rise to a mobile nebulite or migma, which was able to extrude and form the super-eruption or “flare-up” that characterizes Cambro-Ordovician silicic magmatism at the Gondwana margin. Fast, catastrophic crustal melting with large-scale restite entrainment, triggered by the influx of mafic magma-derived fluids, are considered the main cause of the unique features of this Cambro-Ordovician atypical silicic large igneous province of Gondwana. 2022-02-15T11:40:47Z 2022-02-15T11:40:47Z 2022-06 info:eu-repo/semantics/article C. Rodríguez, A. Castro, D. Gómez-Frutos et al. The unique Cambro-Ordovician silicic large igneous province of NW Gondwana: Catastrophic melting of a thinned crust. Gondwana Research 106 (2022) 164–173. [https://doi.org/10.1016/j.gr.2022.01.011] http://hdl.handle.net/10481/72840 10.1016/j.gr.2022.01.011 eng http://creativecommons.org/licenses/by-nc-nd/3.0/es/ info:eu-repo/semantics/openAccess Atribución-NoComercial-SinDerivadas 3.0 España Elsevier