Miocene-Pliocene and Quaternary intrusive rocks and sedimentary deposits from the Central Depression and the Main Cordillera, between 38 and 42°30'S, have been affected by local and regional brittle deformation. Microfault geometry and kinematic analysis along with calculation of deviatoric tensors allowed to determine regional-scale states of stress. Two tectonic events were identified. A Pliocene event, prior to the Quaternary, affects the entire zone of study, and is characterized by a maximum compressional stress a, roughly oriented in an E-W direction. A Pleistocene event corresponds to an overall deformation partitioned into two coeval distinctive states of stress: a compressional stress a, oriented in a N-S to NNE-SSW direction in the fore arc zone, and a dextral transpressional state of stress with 0, striking NE-SW, in the intra-arc zone.