干旱区生态环境知识资源中心

This work documents fault activity and the Neogene’s strain field in northern Chilean Coastal Cordillera. Fault activity is expressed as a group of fault scarps and fault-bend fold scarps whose orientation defines three main domains WNW-ESE, N-S and NNW-SSE. The WNW-ESE and N-S faults show reverse kinematics, and NNW-SSE faults shows dextral-reverse kinematics. Exposure ages using cosmogenic Ne-21 show that the faults disrupt an Oligocene-Miocene landscape preserved at the Coastal Cordillera. Inactive valleys incised in this landscape are offset by the faults showing that faults were active after 4 and 2 Ma. Ar-40/Ar-39 chronology of displaced volcanic tuffs and the deformation of Late Pleistocene sediments indicate that fault activity remain still active during the Quaternary. The deformation regime is constrictional and characterized by subhorizontal shortening in all directions, that is explained by oblique convergence along an active curved continental margin.