Insights into the plumbing system of Colima Volcanic Complex from geophysical evidence

Abstract

The Colima Volcanic Complex (CVC) consists of three stratovolcanoes: El Cántaro, Nevado de Colima and Volcán de Colima, aligned from north to south, with the same chronological order. It has been assumed that the magmatic system also has migrated in the same direction, with the surface trend of the volcanic edifices following the same pattern at depth. However, 3D inversion of gravimetric and aeromagnetic data, combined with spectral analysis (Werner deconvolution) give a detailed analysis of the CVC magmatic system, resulting in a new model of its geometry and migration, which takes into account the rifting process of the Colima Graben, and the separation of the Jalisco and Michoacán Blocks. The resulting fractures favor magma ascent through the western Michoacán Block boundary, which follows a NE-SW direction and gradually changing its angle, becoming more vertical close to Volcán de Colima. This research shows that the CVC magmatic system is best described as a Trans-crustal mush system, characterized by a zone of crystal rich magma storage located within the structural system. The direction of the magmatic migration at depth does not correspond to vertical ascent, illustrated by the lack of correlation with the volcanic edifices on the surface. Additionally, in the results it is possible to identify the separation between distinct phases of the magma, whereby the lower viscosity mobile phase is located in distinct zones within the upper crust, feeding the activity of Volcán de Colima.