Estratigrafía de los depósitos sinorogénicos del Cretácico Superior en las nacientes del Río Blanco, Mendoza (32°57`S)

Abstract

Recent field work in northwestern Mendoza`s Aconcagua fold and thrust belt has been carried out in order to review the Upper Cretaceous stratigraphy and uplift evidences. Three units are involved in this revision: Agrio, Cristo Redentor and Juncal formations. Previous studies proposed a lateral equivalence between the last two units, suggesting that Juncal Formation represents proximal deposits of a volcanic arc while Cristo Redentor Formation corresponds to distal facies. In this work, two angular unconformities are presented. The first one lies between a highly deformed outcrop of Agrio Formation and less deformed volcaniclastic rocks assigned to Cristo Redentor Formation. The second unconformity separates Cristo Redentor Formation and volcanic rocks assigned to Juncal Formation. These observations add evidence of Late Cretaceous uplift phases proposed by previous authors. Additionally, these features, along with recent detrital zircon U-Pb ages, could indicate that Cristo Redentor and Juncal formations are not synchronous. We propose considering Juncal Formation as a younger unit, compared to Cristo Redentor Formation.