Cretaceous and Eocene Rapid Cooling Phases in the Southern Andes (36°–37°S): Insights From Low-Temperature Thermochronology, U-Pb Geochronology, and Inverse Thermal Modeling From Domuyo Area, Argentina

The integration of inverse thermal history modeling of new geochronological data with structural analyses from the western flank of the Domuyo volcano (∼36°30′S) allows us to propose a detailed cooling history of a key region in the Southern Andes. The Domuyo area is located in the northwestern part of the Chos Malal fold-and-thrust belt in the back-arc of the Southern Andes. Despite extensive geological investigations in this region, details about the early stages of Andean deformation remain poorly understood. The present study focuses on the interpretation and integration of new U-Pb, fission track, and (U-Th-Sm)/He data constraining the Cretaceous to Paleogene exhumation history of the Southern Andes at these latitudes. The results indicate two main episodes of rapid cooling during Albian-Campanian and Eocene times that can be related to exhumation driven by two main contractional pulses. The first event promoted basement cooling/exhumation associated with the uplift and erosion of a broad N-S striking antiform; whereas the Eocene episode triggered the inversion of the preexisting N-S striking Manchana Covunco normal fault and the deformation of the Mesozoic sedimentary cover. The two orogenic phases are separated by a potential period of orogenic quiescence during the Paleocene. These new insights highlight the importance of the initial compressional stages of mountain building in the Southern Andes at these latitudes. Fil: Galetto, A.. Universidad de Buenos Aires; Argentina Fil: Georgieva, V.. Universidad Austral de Chile; Chile