info:eu-repo/semantics/article
Subsurface architecture of Las Bombas volcano circular structure (Southern Mendoza, Argentina) from geophysical studies
Fecha
2017-08Registro en:
Prezzi, Claudia Beatriz; Risso, Corina Maria Ana; Orgeira, Maria Julia; Nullo, Francisco Eudoro; Sigismondi, Mario; et al.; Subsurface architecture of Las Bombas volcano circular structure (Southern Mendoza, Argentina) from geophysical studies; Pergamon-Elsevier Science Ltd; Journal of South American Earth Sciences; 77; 8-2017; 247-260
0895-9811
CONICET Digital
CONICET
Autor
Prezzi, Claudia Beatriz
Risso, Corina Maria Ana
Orgeira, Maria Julia
Nullo, Francisco Eudoro
Sigismondi, Mario
Margonari, Liliana
Resumen
The Plio-Pleistocene Llancanelo volcanic field is located in the south-eastern region of the province of Mendoza, Argentina. This wide back-arc lava plateau, with hundreds of monogenetic pyroclastic cones, covers a large area behind the active Andean volcanic arc. Here we focus on the northern Llancanelo volcanic field, particularly in Las Bombas volcano. Las Bombas volcano is an eroded, but still recognizable, scoria cone located in a circular depression surrounded by a basaltic lava flow, suggesting that Las Bombas volcano was there when the lava flow field formed and, therefore, the lava flow engulfed it completely. While this explanation seems reasonable, the common presence of similar landforms in this part of the field justifies the need to establish correctly the stratigraphic relationship between lava flow fields and these circular depressions. The main purpose of this research is to investigate Las Bombas volcano 3D subsurface architecture by means of geophysical methods. We carried out a paleomagnetic study and detailed topographic, magnetic and gravimetric land surveys. Magnetic anomalies of normal and reverse polarity and paleomagnetic results point to the occurrence of two different volcanic episodes. A circular low Bouguer anomaly was detected beneath Las Bombas scoria cone indicating the existence of a mass deficit. A 3D forward gravity model was constructed, which suggests that the mass deficit would be related to the presence of fracture zones below Las Bombas volcano cone, due to sudden degassing of younger magma beneath it, or to a single phreatomagmatic explosion. Our results provide new and detailed information about Las Bombas volcano subsurface architecture.