Neotectonic Deformation in the Foreland Basins of the Sierras Pampeanas of Argentina

The morphotectonic processes that generated the current landscape occurred by NE-strike transtensive-transpressive tectonic events after the Pleistocene. The progressive deformation of the Sierras Pampeanas towards the east is manifested in the topographic elevations of the Chaco Plain (Dorsal Mujer Muerta and topographic highlands of Otumpa, San Guillermo, El Recreo, and Mancilla). These positive reliefs interfere with and divert surface runoff drainage. At the beginning of the deformation, the Salinas Grandes depression was fed by the Sali River through the San Bernardo River. The advance of the neotectonic deformation generated the Alto de Mancilla that diverted the Sali River east to the Saladillo River, filling the Ambargasta lagoon with water. Later, this drainage moved towards the Mar Chiquita lagoon. The definitive separation of the Salí-Dulce river from Laguna Grande and Laguna de Ambargasta occurred ca. 250 to 300 years ago. The transfer area between the Dulce and Salado rivers, north of the Mar Chiquita Lagoon, shows that the topographic survey continues. This process implies that shortly, the Salado River could completely capture the Dulce River with its definitive separation from the Mar Chiquita lagoon.