Quaternary deformation in the Neuquén Basin, explained by the interaction between mantle dynamics and tectonics

SAGRIPANTI, LUCÍA; BRUNO COLAVITTO; ANA ASTORT; ANDRES FOLGUERA

Opening and closure of the Neuquén Basin in the Southern Andes

Springer

Año: 2020; p. 442 - 457

Quaternary deformations described in the retroarc region at the latitudes of the Neuquén Basin can be divided into two main groups: a northern group characterized by Quaternary deformation zones concentrated near the main topographic breaks of different morphostructural systems, while a second group located in the southern Neuquén Basin distinguished by disconnected, sparced and noncontinuous Quaternary deformational zones. In the northern Neuquén Basin, evidence of active deformation is associated with the Frontal Cordillera (33°?34°S); while in the foreland area, young deformations concentrate in the San Rafael Block. In the southern Neuquén Basin, a western deformational belt constitutes the continuation to the north of an intra-arc fault system associated with dip- and strike-slip displacements in a strain-partitioned regime (Liquiñe?Ofqui fault system). However, to the east, the mountain front area is associated with extensional and constructional quaternary structures. Isolated evidence of Quaternary deformation, regional uplift, and development of non-equilibrated fluvial profiles are recognized in the Tromen and Auca Mahuida volcanic plateaux and sierra de Cara Cura-sierra de Reyes area. These short and unconnected systems are explained through an intricate pattern of asthenospheric anomalies evidenced from magnetotelluric data and following previous proposals of sublithospheric controls related to the tearing of the subducted Nazca plate evidenced by tomographic data. We suggest, based on previous works, that the thermally weakened crust at the southern Neuquén Basin latitudes could be the main control responsible for focalizing contractional, extensional and transpressional deformations in isolated mountain systems.