Structural evolution and exhumation events recorded in the Huingancó Granodiorite, Cordillera del Viento, Southern Central Andes, Argentina

Abstract

This study seeks to unravel the exhumation history of Permian granodiorites corresponding to the Huingancó volcano-plutonic Complex in the southern sector of the Cordillera del Viento (∼37°S), located within the Chos Malal fold-thrust belt. In this context, mineral chemistry analyses were conducted on the granodiorites using electron microprobe data to infer the P-T conditions of emplacement, resulting in 700–900 °C and pressures ranging between 1 and 2.4 kbar. Employing a geostatic gradient of 3.7 km/kbar, these values give an estimate of emplacement depths between 4 and 9 km. In order to understand their exhumation path, five samples from the Huingancó Granodiorite were taken along the Huaraco creek on the western flank of the Cordillera del Viento anticline to perform apatite fission track (AFT) analysis. This analysis yielded new cooling ages for the study area ranging between 50 and 80 Ma. Furthermore, inverse thermal modeling using the fission track data revealed two significant exhumation events during the Andean cycle: one during the Late Cretaceous-Paleocene and the other in Miocene times, separated by a period of gradual cooling or stability during Eocene-Oligocene times. These important cooling events are associated with the main construction phases of the Cordillera del Viento. Finally, to characterize its deformation evolution, a structural kinematic model is proposed based on a balanced structural section and its reconstruction to its non-deformed pre-Cretaceous state. The resulting model allows us to identify the structures and mechanisms of uplift rising the Cordillera del Viento, and their association with the main exhumation events depicted in the inverse thermal modeling. The main structure of the Cordillera del Viento corresponds to a fault bending fold that involves the basement in the deformation. Subsequently, its insertion as an intracutaneous wedge is related with the development of the thin-skinned structures at the internal sector of the Chos Malal fold and thrust belt.