CONICET | Buscador de Institutos y Recursos Humanos

The dominant Cenozoic structural grain in northwestern Argentina trends northesouth. However,several oblique folds have been mapped, mainly in the Cordillera Oriental and the Sistema de Santa Bárbara. Two oblique NEeSW-trending anticlines are well exposed in the Luracatao Valley-Salta, along the western border of the Cordillera Oriental. These oblique anticlines are defined by the Palaeogene Santa Bárbara Subgroup and are cut by the reverse faults bounding the Luracatao Valley. We constructed analogue models to simulate the generation of oblique NEeSW anticlines inside the narrow, trough-like Luracatao Valley. Orthogonal compression and basement oblique heterogeneities, oblique compression and basement oblique heterogeneities, and oblique compression configurations were tested in the models. The first two configurations simulate the anticline formation well. In addition, we analyse dextral rotation and the influence of Neoproterozoic basement/Cretaceous rift structures as the cause of the oblique orientation. The analogue models suggest pre-Andean oblique structures controlling the oblique orientation of these Andean folds despite being a second-order planes of weakness.