Identificación y caracterización de los últimos productos eruptivos de la fase resurgente de la Caldera de Chalupas

Abstract

The Chalupas caldera (17 km in diameter) is located in the Cordillera Real, 80 km southeast of Quito and 30 km northeast of Latacunga. This depression was formed due to a large and unique rhyolitic eruption (~ 100 km3 of volume) this deposit is called "Ignimbrita de Chalupas" (~ 211 ka.) The Chalupas magmatic chamber is located in the metamorphic basement of the CR and is located between 4 and 8 km below surface. Observations during the field campaigns and the collection of representative samples to perform petrographic and geochemical analyzes, are the main methods to study the rocks of the last eruptive period. The last eruptive products have been identified with an age of between 35-40 ka, This age was estimated with 14C dates and by its morphology eroded by the Last Late Glaciation glaciers. The identified products correspond to the dacitic composition dome called “Buenavista” (possibly had a collapse morphologically identified since no outcrops were found) and to the andesitic-dacitic lava flow called “Huahui”. Both located to the east of the Quilindaña volcano. A layer of rhyolitic ash flow associated with Buenavista indicates a bimodal character in the last period of activity of Quilindaña.