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dc.contributor.authorCastro, Antonio
dc.contributor.authorMolina Palma, José Francisco
dc.identifier.citationCastro, A... [et al.], 2021, Secular variations of magma source compositions in the North Patagonian batholith from the Jurassic to Tertiary: Was mélange melting involved?: Geosphere, v. 17, no. 3, p. 766– 785, []es_ES
dc.descriptionThis research was funded by the Spanish Agency of Science and Technology (Projects CGL201348408-C3-1-P and PGC2018-096534-B-I00) and the University of Huelva. Rodriguez is grateful for a Juan de la Cierva postdoctoral research grant. This is IBERSIMS publication 49.es_ES
dc.description.abstractThis study of Sr-Nd initial isotopic ratios of plutons from the North Patagonian batholith (Argentina and Chile) revealed that a secular evolution spanning 180 m.y., from the Jurassic to Neogene, can be established in terms of magma sources, which in turn are correlated with changes in the tectonic regime. The provenance and composition of end-member components in the source of magmas are represented by the Sr-Nd initial isotopic ratios (Sr-87/Sr-86 and Nd-143/Nd-144) of the plutonic rocks. Our results support the interpretation that source composition was determined by incorporation of varied crustal materials and trench sediments via subduction erosion and sediment subduction into a subduction channel melange. Subsequent melting of subducted melanges at mantle depths and eventual reaction with the ultramafic mantle are proposed as the main causes of batholith magma generation, which was favored during periods of fast convergence and high obliquity between the involved plates. We propose that a parental diorite (= andesite) precursor arrived at the lower arc crust, where it underwent fractionation to yield the silicic melts (granodiorites and granites) that formed the batholiths. The diorite precursor could have been in turn fractionated from a more mafic melt of basaltic andesite composition, which was formed within the mantle by complete reaction of the bulk melanges and the peridotite. Our proposal follows model predictions on the formation of melange diapirs that carry fertile subducted materials into hot regions of the suprasubduction mantle wedge, where mafic parental magmas of batholiths originate. This model not only accounts for the secular geochemical variations of Andean batholiths, but it also avoids a fundamental paradox of the classical basalt model: the absence of ultramafic cumulates in the lower arc crust and in the continental crust in general.es_ES
dc.description.sponsorshipSpanish Agency of Science and Technology CGL201348408-C3-1-P PGC2018-096534-B-I00es_ES
dc.description.sponsorshipUniversity of Huelvaes_ES
dc.description.sponsorshipJuan de la Cierva postdoctoral research grantes_ES
dc.publisherGeological Society of Americaes_ES
dc.rightsAtribución-NoComercial 3.0 España*
dc.titleSecular variations of magma source compositions in the North Patagonian batholith from the Jurassic to Tertiary: Was mélange melting involved?es_ES

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