Graciela Mabel Suvires

Geomorphology of Talacasto alluvial fan, Precordillera of San Juan, Argentina

ABSTRACT We present a 1:50,000 geomorphological map of the Talacasto river alluvial fan (93 km2), located in the Central Andean Precordillera of Argentina. The aim of this map is to identify and classify dynamic and potentially destructive geomorphological processes such as gully erosion, headward erosion, concentrated erosion, laminar erosion and similar features that are present in an alluvial fan, so as to identify unstable sectors for public infrastructure. This map is the result of combining remote sensing data, aerial photographs analysis and fieldwork. Landforms and active geomorphological processes are identified, classified and illustrated for this Quaternary alluvial fan. Four Quaternary landscape subunits were classified, taking into account morphogenetic characteristics and erosional processes such as: (1) Exhumed and erosional landforms inducted by neotectonic activity; (2) Alluvial landforms; (3) Polygenetic landforms covered in glacis; and (4) Playa lake landforms. The presence of desert pavements and salt-hardened subsoil formations contributes to the generation and transmission of surface runoff during summer heavy rains, causing alluvial hazards and damages in routes and roads.