Abstract

MARO, Guadalupe  and  REMESAL, Marcela B. Bimodal volcanism of the Cerro Corona volcano in the Alta Sierra de Somún Curá (Río Negro province). Rev. Asoc. Geol. Argent. [online]. 2012, vol.69, n.1. ISSN 0004-4822.

The Cerro Corona is a shield volcano situated in the Alta Sierra de Somún Curá, one of the tertiary volcanic complex that constitute the Meseta de Somún Curá, in the Extrandean Patagonia. It is the highest center in the region and it is compound mainly of basaltic trachyandesites, with trachytic variations on its flanks and crater. Despite the compositional bimodality with an important compositional gap between 54% and 58% in weight in SiO₂, this work suggests that trachytes are the product of the evolution of basaltic trachyandesites through fractional crystallization, with some influence of mafic recharge to the magmatic chamber, in agreement with the presence of disequilibrium textures in fenocrystals, essentially in felsic rocks.

Keywords : Somún Curá; Fractional crystallization; Intraplate magmatism; Tertiary.

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