Abstract

VARELA, Ricardo; BASEI, Miguel A.S.  and  PEREYRA, Claudia P.. U-Pb dating of the Paimán Granite, Sierra de Paimán, Chilecito, La Rioja. Rev. Asoc. Geol. Argent. [online]. 2008, vol.63, n.1, pp.97-101. ISSN 0004-4822.

Conventional U-Pb zircon ages for the Paimán Granite are presented. The magmatic unit crops out in the eastern border of the Famatina range. Five zircon fractions were analysed from a coarse porphyritic granitoid, the major component in the Paimán-Chilecito area. Results are concordant for the five fractions and the mean 206 Pb/ 238 U age of 477.6 ± 4.1 Ma is Early Ordovician. This age confirms that the Paimán Granite is part of the Ocloyic magmatic phase and Famatinian belt. The present age together with the previous U-Pb ages from granitoids of the Famatinian belt between 28º and 33º S suggest that the magmatic activity occurred over a short time span of about 20 Ma, following no noticeable internal polarity within the belt.

Keywords : Paimán Granite; Chilecito; U-Pb age; Early Ordovician; Famatinian belt.

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