Abstract

SALVATORE, Marcos et al. Caracterización litogeoquímica del granito La Chinchilla y su relación con el uranio, siella de Velasco, provincia de La Rioja. Rev. Asoc. Geol. Argent. [online]. 2013, vol.70, n.3, pp.341-350. ISSN 0004-4822.

The Chinchilla pluton is a granitic subelipsoidal shaped body that crops out in the central area of the Sierra de Velasco, La Rioja, Argentina, covering an approximate area of 3.75 km². This small body sharply intrudes into Huaco porphyritic granite, or by pegmatoid contacts and in some sectors stockscheider development. Three granite facies were defined based on their textural characteristics, mineral composition and natural radioactitvity. The porphyritic facies presents major areal extent, whereas the equigranular facies and the fine grain boundary facies are poorly represented. All facies have a monzogranitic modal composition. Chemical analysis show high uranium content for all facies, being the equigranular which shows the greatest tenors. This facies is also slightly enriched in alkalis, incompatible elements (F, Rb, Sn and U) and Th/U relations less than 0,8 showing a greater degree of fractionation.

Keywords : Petrography; Geochemistry; Uranium; La Chinchilla pluton.

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