Resumo

MARTINEZ, Amancay N.; CODEGA, Daniel  e  AGUILERA, David. Petrographic study of the pyroclastic facies of the Cerro Varela Formation in the south of the Sierra de San Luis. Rev. Asoc. Geol. Argent. [online]. 2010, vol.67, n.3, pp.403-407. ISSN 0004-4822.

In the San Luis province, there are three sub-basins called Las Salinas, Beazley and Mercedes. These basins correspond to elongated rift depocenter with a NO orientation that host Triassic igneous rocks with thicknesses that reach 4,000 meters. The igneous rocks from Cerro Varela Formation, part of the homonym hill, is the last vestige of the southern Sierra San Luis. The Triassic rhyolites that crop up in the sierra de Varela, are placed within a structural pattern associated with the formation of extensional basins. Crystal tuffs of Cerro Varela are corresponds to tuffs with high and low degree of welding, of rhyolitic composition and interpreted as pyroclastic deposits. For its lithology, age and regional context, the rocks of the Cerro Varela Formation integrate the Gondwanic magmatism of Permo-Triassic age, related to the Choiyoi Group of the Cordillera Frontal of Mendoza and San Juan.

Palavras-chave : Gondwana; Choiyoi Group; San Luis; Permo-triassic magmatism.

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