Abstract

BOEDO, Florencia L; VUJOVICH, Graciela I  and  BARREDO, Silvia P. Characterization of ultramafic, mafic and metasedimentary rocks of the Cordón del Peñasco, western Precordillera, Mendoza. Rev. Asoc. Geol. Argent. [online]. 2012, vol.69, n.2, pp.275-286. ISSN 0004-4822.

In Cordón del Peñasco area, located in northern Mendoza province, western Precordillera, metasedimentites are in tectonic contact with a mafic-ultramafic association. The former have been under greenschist facies metamorphism and two associations have been recognized: carbonate metasiltstones and metasandstones and metapelites. The mafic-ultramafic association is represented by serpentinized peridotites derived from dunites and harzburgites, layered gabbros in granulite facies; diabase dikes or sills, amigdaloid metabasalts and metahialoclastic rocks with low grade metamorphism. In this contribution, we have estimated metamorphic temperatures on a mafic granulite (layered gabbro) based on garnet-clinopyroxene, obtaining a temperature of 884°C. This suggests that these bodies have been under high temperature metamorphism and were later retrogressed to greenschist facies, evidenced by mineralogical and textural aspects. Regarding the metasedimentary units, the paleoenvironment of the metasandstones and metapelites association corresponds to a continental slope with turbiditic sedimentation, as suggested by sedimentary structures. The carbonate metasiltstone unit belongs to a deep marine environment. These units have been assigned to Eopaleozoic times based on stratigraphic criteria and deformed and metamorphosed in late Devonian as a consequence of Chanica orogeny.

Keywords : Western Precordillera; Mafic-ultramafic rocks; Metasedimentites; Mafic granulite; Thermometry.

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