Morphostructural evolution of the Medeiros Hills, Lerma Valley, Cordillera Oriental, Northwestern Argentina

GARCÍA, VICTOR; HONGN, FERNANDO; GATICA, SERGIO; VERA, DARÍO; PARADA, MARTÍN

Antofagasta

Congreso; VIII Congreso Geológico de Chile; 2012

Sociedad Geológica de Chile

The Lerma valley is an intermontane tectonic depression located in the Cordillera Oriental of NW Argentina. Basement-cored thrust sheets are flanking the valley and controlling its N-S elongated shape. The uplift of these basement blocks took place during late Miocene to Plio-Pleistocene, synchronously with the deposition of fluvial-alluvial sequences. The Medeiros hills are located at the northern extreme of this valley and represent the geomorphic expression of the southward propagation of the Vaqueros anticline. In these hills, middle to upper Pleistocene fluvial conglomerates are uplifted more than 150 meters with respect to its stratigraphic position in the undeformed basin. The pattern of six strath terraces sculpted in the northern sector of the hills has been interpreted as evidences of the forced migration northward of the Vaqueros river during recent uplifting events. The main objectives of this research are to describe the structure of the hills and interpret its tectonic evolution along the Quaternary using new structural, geomorphologic and topographic data.