Análisis y reinterpretación de datos gravimétricos de la caldera de Chalupas.

Abstract

The gravimetric method measures the changes in the acceleration of gravity over a terrain in order to detect the variations of densities present in the subsoil and although this method does not match the resolution and precision of direct observations, it is a fast, cost-effective and non-invasive procedure that serves to make geological models that guide investigation. The Chalupas caldera is located in the central-eastern part of the Ecuadorian Andes in the province of Napo, within the Tena and Archidona, 80 km southeast of Quito, 35 km northeast of the city of Latacunga and 80 km to the northwest of Tena. Its formation is due to a large rhyolitic eruption in a single eruptive event that caused the collapse and deposit of the Chalupas Ignimbrite. Through the use of the gravimetric method and the integration of geological information, it was possible to obtain geophysical results that show well-defined residual Bouguer anomalies that correlate with the caldera structure where anomalies with low gravimetric values have a radial shape and are associated with the collapse of the caldera, which was later filled with less dense rocks such as the Chalupas ignimbrite and post-caldera lava flows from the Quilindaña volcano. The highest gravity levels are associated to the eastern zone with high-density rocks corresponding to the metamorphic basement. In addition, the presence of regional structures such as the Peltetec fault the western limit of the caldera and the Baños fault that passes under Quilindaña volcano in a N20°E direction.