<p>The locus of active deformation along the Andean orogenic front at the latitude of the Pampean flat slab remains debated, particularly regarding whether late Quaternary tectonic activity is concentrated along the eastern or western margins of the Eastern Precordillera. We present new geomorphic and structural evidence, indicating that the western front of the Sierra Chica de Zonda is a locus of late Quaternary deformation within the Villicum–Zonda–Pedernal Fault System. Results reveal widespread geomorphic markers of late Quaternary faulting, including fault scarps, uplifted and tilted alluvial surfaces, and knickpoints in longitudinal river profiles. The Zonda Fault is subdivided into four structural sections that display variable segmentation, fault complexity, and deformation intensity, with the Central Zonda section showing the highest density of fault traces and the most complex deformation patterns. These observations support a piedmont foreland deformation model, involving the interaction of master boundary faults and antithetic structures within the piedmont. Spatial relationships between deformed Quaternary surfaces and fault traces indicate repeated late Pleistocene deformation, possibly extending into the Holocene. These findings identify the western front of the Sierra Chica de Zonda as a key locus of recent deformation, with important implications for seismic hazard assessment and the kinematic evolution of the Andean foreland.</p> Graphical Abstract <p></p>