Análisis tectónico-estructural en las áreas de Loma Negra, Puesto Zúñiga y La Yesera

Abstract

A tectono-structural study was carried out in order to interpret the tectonic evolution of the Loma Negra, Puesto Zúñiga, and La Yesera blocks. As the result of the structural and tectonic analysis of these areas, it is proposed an evolutionary model: during the Late Triassic – Early Jurassic, as the result of oblique extension under the action of NNE-SSW minimum principal stress, two extensional systems were developed (NW-SE and WNW-ESE) forming depocenters of different order. Two sectors divided by a NE – NNE transfer zone are identified, the western and eastern ones. The first transpressive deformation evidence recognized in La Yesera area during Late Pliensbachian – Early Toarcian is characterized by a relief inversion due to the selective inversion of some of the pre-existing normal faults and by the generation of reverse faults nucleated in previous extensional faults. During the middle to late Toarcian - Aalenian the deformation continues in the lineaments of Lago Pellegrini, Puesto Zúñiga and Loma de María and in the La Yesera zone. A period of tectonic calm is recorded in the Aalenian, then the deformation is reactivated during the late Aalenian to early Bajocian, being more active in the Lago Pellegrini, Puesto Zúñiga and Loma de María lineaments. In the Middle-Late Bajocian, the deformation is mainly concentrated along reverse faults located along the Puesto Flores - Galdame structural systems with a mainly NE - ENE orientation. The deformation continues to register pulses during the late Bajocian and for the Bathonian. It is proposed that from the Pliensbachian to the Aalenian the stress field for the study area was dominated by a local SW-NE maximum horizontal stress as the result of the Huincul Ridge push, based on the analysis of the active structures, their orientation, kinematics, and the associated deformation pulses. From the Aalenian to the Bathonian it is proposed that the deformation was controlled by the NW - SE regional stress field.