Magmatic and tectonic evolution of the Oligocene Valle del cura basin, main Andes of Argentina and Chile: Evidence for generalized extension

Abstract

The magmatic history and tectonic evolution of the Valle del Cura region has received the attention of several studies in recent years, particularly as part of a larger area of interest named the Indio Belt. These studies have suggested an Eocene volcanic sequence known as the Valle del Cura Formation. The present study, based on extensive field work, robust geochronological and geochemical datasets, shows an Oligocene to early Miocene age for this unit, similar to the Doña Ana Group. The tectonic setting that controlled the volcanism of the Valle del Cura Formation was extensional and corresponds to a retro-arc position of the main arc volcanism of the Doña Ana Group. The field evidence combined with radiometric and geochemical data demonstrate the synextensional characteristic of the volcanic sequence of the Valle del Cura Formation and the Doña Ana Group at these latitudes. This characteristic was dominant at the central part of the Pampean Flat Slab (29°-30°S).