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Author(s): Helena C B Martins
Helena Sant'Ovaia
Fernando Noronha
Title: Late-Variscan emplacement and genesis of the Vieira do Minho composite pluton, Central Iberian Zone: Constraints from U-Pb zircon geochronology, AMS data and Sr-Nd-O isotope geochemistry
Issue Date: 2013
Abstract: In the Central Iberian Zone synorogenic (syn- and late-D-3, the last deformation phase) composite batholiths of biotite-rich granitods with peraluminous character are well represented. We report here U-Pb zircon and monazite ages, geochemical, Sr-Nd-O isotopic data and Anisotropy of Magnetic Susceptibility (AMS) studies for the late-D-3 Vieira do Minho pluton, in northern Portugal. AMS reveals the paramagnetic behaviour of these granites and the magnetic fabric enhances the major role of NW-SE regional anisotropies on controlling the ascent and emplacement of the magmas. Magnetic anisotropy and medium temperature microstructures also point out the evolution of regional tectonics during crystallization of the magma. U-Pb zircon and monazite analyses yield consistent ages of 310 +/- 2 Ma and 312 +/- 2 Ma, interpreted as emplacement age. The Vieira do Minho pluton consists of two peraluminous monzogranites, the VMG and the MRG. Both have similar epsilon(Nd) values (VMG= -52 to -5.7; MRG= -4.98 to -5.96) but the VMG is slightly enriched in Sr-87/(86)(i)=0.7087-0.7098 as well as in delta O-18 in the range of 10.6 parts per thousand to 11.0 parts per thousand than the MRG with Sr-87/(86)(i)=0.7064-0.7075 and delta O-18=9.9 parts per thousand-10.5 parts per thousand. These granites are associated with coeval scarce grabroic intrusions and/or mafic microgranular enclaves which are not considered as mafic precursors of the associated granitic magmatism. Instead, a lower metaigneous crustal source, at different levels, is proposed based on the available data set.
Subject: Ciências Naturais, Ciências da terra e ciências do ambiente
Natural sciences, Earth and related Environmental sciences
Scientific areas: Ciências exactas e naturais::Ciências da terra e ciências do ambiente
Natural sciences::Earth and related Environmental sciences
Related Information: info:eu-repo/grantAgreement/FCT - Fundação para a Ciência e Tecnologia/PROJETOS ESTRATÉGICOS/PEst-OE/CTE/UI0039/2011/Projecto Estratégico - UI 39 - 2011-2012/PEst-OE/CTE/UI0039/2011
Document Type: Artigo em Revista Científica Internacional
Rights: openAccess
Appears in Collections:FCUP - Artigo em Revista Científica Internacional

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