El Pinacate volcanic field, Northwest Mexico: An example of a shield cluster; [Campo volcánico El Pinacate, noroeste de México: Un ejemplo de un cúmulo de escudos]

Abstract

El Pinacate volcanic field, Northwest Mexico, includes a large shield volcano (Sta. Clara) and more than 400 vents, most of which are cinder cones and a few maars of Pleistocene and recent age. Previous studies of the distribution of those vents focused on the identification of preferred orientations of vent alignments, paying little attention to the identification of clusters of vents within the field. In this work several methods of spatial distribution analyses are combined together to describe the spatial structure of the distribution. As a result, four main structures are identified, each interpreted as a long-lived volcanic system that has remained active throughout the history of the volcanic activity on the region. Interaction of the axes of activity within those structures with an older listric fault that crosses the field from NW to SE is responsible for the apparent difference in distribution observed in the north and south halves of the field. Differences to the depth of the Curie isotherm also contribute to the observed differences on the vent distribution at the surface. Although the influence of tectonic stresses is very important in controlling the location of activity on this field, in this work we show that it is not necessary to invoke a change in the orientation of those stresses to explain the evolution of the region. © This is an open access article under the CC BY-NC-SA license (https://creativecommons.org/licenses/by-nc-sa/4.0/)