Resumo

CINGOLANI, Carlos A; URIZ, Norberto; CHEMALE JR, Farid  e  VARELA, Ricardo. The monzonitic rocks of the eastern sector of the Cacheuta Pluton, Precordillera of Mendoza: geochemical signature and U/Pb age (LA-ICP-MS). Rev. Asoc. Geol. Argent. [online]. 2012, vol.69, n.2, pp.195-206. ISSN 0004-4822.

In the south of the Precordillera of Mendoza crops out the Cacheuta Pluton formed with an eastern belt of gray-green monzonite to granodiorite type rocks (Boca del Rio) and a subsequent larger surface outcrop of pink granitic rocks. In this work are offered new whole rock geochemical and geochronological U/Pb (LA-ICP-MS) data on 25 zircon crystals extracted from three monzonitic rock samples. These rocks have subalkaline and metaaluminous signature, with enrichment in light REE with less negative Eu anomaly. The analyses of zircon crystals by U/Pb geochronology show that a main mode of ages is 253 -258 Ma that represent the Late Permian. Then the isotopic data span between the Carboniferous with 302 Ma as the oldest zircon record and other one that presents the age of 249 Ma corresponding to the Early Triassic. With these data, the composed Cacheuta Pluton belongs entirely to the Gondwanian orogenic cycle and is coeval with the Permian-Triassic volcanic activity of the Choiyoi Group.

Palavras-chave : Granitoids; Gondwanian cycle; U/Pb, Rb/Sr; Nd isotopes; Permian.

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