Ignimbrites of the Río Las Papas valley (Cordil lera de San Buenaventura, Catamarca): a petrological and geochemical approximation

Acta geológica 23 (1-2) 2011

Abstract

Thick ignimbrite deposits were identified along the margins of the Las Papas river , at the southeastern part of the Cordillera de San Buenaventura (Catamarca). From field-relatio ns, petrography and geochemistry we distinguish two pyroclastic units, Las Papas Ignimbrit e and Las Juntas Ignimbrite, both of Upper Miocene age. Although both of these units are calk- alkaline and rhyolitic in composition, their different trace elements concentrations, induration and welding degrees, and type content of lithic fragments and pumice allow the separation in two different ignimbrites. Although it was not possible to identify the eruptive centre/s asso ciated with these ignimbrites, based on their location, lithic fragment characteristics and the paleotopography, it is considered that they were located in the eastern sector of the Cord illera de San Buenaventura.