%0 Journal Article
%A Alasino, Pablo H.
%A Dahlquist, Juan A.
%A Pankhurst, R.J.
%A Galindo Francisco, María Del Carmen
%A Casquet Martín, César
%A Rapela, Carlos W.
%A Larrovere, M.A.
%A Fanning, C.M.
%T Early Carboniferous sub- to mid-alkaline magmatism in the Eastern SierrasPampeanas, NW Argentina: A record of crustal growth by the incorporation ofmantle-derived material in an extensional setting
%D 2012
%@ 1342-937X
%U https://hdl.handle.net/20.500.14352/43847
%X A recently discovered granitic intrusion at Cerro La Gloria in western Sierra de Famatina (NW Argentina) isrepresentative of sub- to mid-alkaline Carboniferous magmatism in the region. The main rock type consistsof microcline, quartz and plagioclase, with amphibole, magnetite, ilmenite, biotite, epidote, zircon, allaniteand sphene as accessory minerals. We report a U–Pb zircon SHRIMP age for the pluton of 349±3 Ma(MSWD=1.1), i.e., Tournaisian. Whole-rock chemical composition and Nd isotope analyses are compatiblewith an origin by melting of older mafic material in the lower crust (εNdt between −0.58 and +0.46 andTDM values of about 1.1 Ga). The pluton is intruded by penecontemporaneous to late alkaline mafic dykesthat are classified as back-arc basalts. Coeval, Early Carboniferous A-type granites occur farther east in the SierrasPampeanas, probably generated during lithospheric stretching. Overall, the Early Carboniferous graniticrocks show a west-to-east mineralogical and isotopic zonation indicating that magma genesis involved agreater contribution of juvenile material of mantle character to the west. Based on the observed patternsof geochronology, geochemistry and field relationships we suggest that A-type magma genesis in the EasternSierras Pampeanas was linked to an Andean-type margin where the lithospheric mantle played a role in itsgeneration.
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