Eruptive centre localization by means of aeromagnetometry in the central area of the Cura Valley, San Juan, Argentina: implications for the evolution of the Cenozoic arc/retroarc.

Abstract

A solid geology map was prepared for the study region, based on the aeromagnetic survey and geological mapping of the region. The geological-structural analysis of the aeromagnetic survey has identified circular features interpreted as anular fractures associated with eruptive centres. The Brea eruptive centre is of shallow nature; there is no evidence of the occurrence of an associated subvolcanic body; it is located in a structurally favourable setting characterized by the intersection of a submeridional thrust and a system of NE-trending fractures; its age is assigned to the Eocene and it is located in a back-arc setting, considering the location of the contemporaneous volcanic-arc deposits. The Zancarrón eruptive centre is regarded as a volcanic caldera, an observation which is consistent with the geological evidences of the presence of a Miocene strato-volcano in this region. There is geophysical evidence that indicates Oligocene volcanic rocks underlying the core of the eruptive centre, which suggests that its magmatic activity would have started during the Oligocene; in this case, the Zancarrón eruptive centre would represent an additional centre of the Doña Ana Group (Oligocene) similar to the one recognized within the Chilean territory. Based on the association of this group with mineralised hydrothermal alteration zones within the Valle del Cura region, the possible identification of covered Oligocene volcanic rocks may be of a special interest for mining exploration.