sedimentary rocks (conglomerate, sandstones and argillite), (e)
Quaternary colluvial-alluvial deposits, (f) Modern unconsolidated
deposits, sand, silt and clay, that are restricted to narrow river
channels and to the valleys.
The Central Precordillera has been described as a typical thinskinned
thrust-and-fold belt, with Neogene crustal shortening
dipping west, and imbricated structures rooting down towards a
10e15 km deep main decollement ( Allmendinger et al., 1990).
Reverse faults with Quaternary tectonic activity are found in the
eastern piedmont of the Cordon de Las Osamentas ( Perucca and
Onorato, 2011). All the faults are located at a distance between 2
and 20 km from the debris rockslides area. NeS trending thrust
faults affect the lower or distal part of the alluvial fans, east-facing
scarps up to 10-m high define the fault trace.