Quaternary landscape evolution and human occupation in northwestern Argentina

Abstract

Our study area is located in northwestern Argentina. It is a semiarid valley in which developed agricultural pre-Columbian settlements were located. The objectives of our research were to establish the geomorphological characteristics of the area, its relative chronological development, and the relationships between geomorphological development and pre-Columbian settlements. Pre-Quaternary lithologies are represented by a metamorphic basement that is commonly exposed on slopes and belongs to the Precambrian and Cambrian periods. Tertiary sediments from several formations are exposed over an extensive surface forming cuesta relief landforms. Quaternary landscape units were classified according to their genesis into structural-denudational landforms (denudational slopes and structural scarps), denudational landforms (covered glacis), fluvio-alluvial landforms (alluvial fans, fluvial fans, and fluvial terraces) and aeolian forms (stabilized dunes). Archaeological sites belonging to the Formative (500 BC-AD 1000) and Regional Development (AD 1000-1500) periods were identified. The main archaeological sites are located on the surfaces of debris-flow deposits and some covered glacis. They are characterized by the presence of residential units together with agricultural structures (terraces and irrigation channels). The earlier settlements (Formative period) are restricted to alluvial fan landforms (debris-flow deposits), where present hydrological supply is lower than in the rest of the study area. Later settlements (Regional Development period) are juxtaposed with earlier settlements in the south of the area, where present hydrological supply is higher owing to larger river catchments and moistureladen winds from the SE.