Geophysical indicators of Neogene strike-slip faulting in the Desaguadero–Bermejo tectonic lineament (northwestern Argentina)

The depocenters of the Bermejo and Ischigualasto-Villa Unión Cenozoic sedimentary basins lie on opposite sides of the Desaguadero–Bermejo fault and show a left-lateral offset of about 70 km. We postulate that this offset in fact reflects strike-slip displacement along the Desaguadero–Bermejo fault related to late Andean tectonics. This conclusion is supported by the residual Bouguer anomaly map and by the total magnetic map reduced to the pole, as well as by refraction and reflection seismic data and earthquake focal mechanisms. We put forward a gravity model that explains the structural history of these two basins. The model proposes that an originally single foreland basin was divided into two basins by strike slip along the Desaguadero–Bermejo fault. The eastern portion of this original basin moved northward, uplifted, and rotated clockwise.