Geomorphology of the alluvial fans in Colalao del Valle-Quilmes area (Santa María Valley, Tucumán Province, Argentina)

Abstract

The geomorphological map of the alluvial fans in the Colalao del Valle-Quilmes area represents the first detailed map of the Santa María Valley, Northwest Argentina. The map was made using photointerpretation of aerial photographs and Google Earth images. The initial working scale was 1:10,000 and then reduced to 1:27,000 to fit ISO A1 size. Final drawings were produced using FreeHand 11. The area is characterized by the presence of coalescent alluvial fans developed on four levels. These fans end at the floodplain of the Santa María River. Sand mantles and dunes are present in this area, with old channels of the main river forming abandoned wetlands. A Holocene fault affects the distal area of some fans, whilst the apices of several alluvial fans have archaeological settlements. This study area presents an excellent example of regional Holocene evolution. Recent and present fluvial dynamics, aeolian activity, and the Holocene fault show high geomorphological activity. As a consequence, the information contained in the geomorphological map may be relevant to the establishment of risk areas for human settlements. Moreover, the map could be useful for planning conservation measures for the Prehispanic villages.