Using gemorphological markers to discriminate Neogene tectonic activity in the Precordillera of North Chilean forearc (24-25°S)

We study the Neogene tectonic activity in a sector of the Precordillera in the Andean forearc analysing aerial photographs, satellite images and fieldwork data. The interpretation of alluvial landforms, drainage organisation and evolution of intermittent river networks affecting post-Lower Miocene deposits allow us to recognize low intensity tectonic processes controlling the landscape evolution. All these geomorphological markers indicate no strike-slip offsets, but repeated and small tectonic pulses that reactivate previous structures originated under a transpressive context. The observed deformation pattern is the consequence of E-W orthogonal compression resulting in limited shortening, related to the accommodation of deformation in the Chilean forearc of the Neogene uplift of the Altiplano-Puna.