Abstract

STRAZZERE, L.  and  GREGORI, D.A.. Interpretation of the volcaniclastic sequence of the Choiyoi Group in the Santa Elena Creek, Precordillera of Mendoza. Rev. Asoc. Geol. Argent. [online]. 2005, vol.60, n.3, pp.486-494. ISSN 0004-4822.

Permo-Triassic volcanic rocks assigned to the Choiyoi Group crop out at Quebradas de Santa Elena and del Telégrafo, in the Mendoza Precordillera. Eight events of different magnitude are the results of recurring volcanic eruptions. Consolidated deposits are represented by densely-welded and partially-welded pyroclastic flows, as well as by vitrophyres and perlites. Unconsolidated deposits include units from pyroclastic surges and ash-pumice falls. Detailed observations indicate upwards increasing acidification, varying from phenodacitic to phenorhyolitic rocks. On the basis of their lithological characteristics, these rocks are correlated with similar facies in the Horcajo Formation described in the Los Patos valley, San Juan province. The structural style is represented by large open folds. The sequence thins toward the NW and SE, suggesting a NE-SW flow direction.

Keywords : Choiyoi Group; Volcanic successions; Densely welded ignimbrites; Precordillera Mendoza; Argentina.

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