Morphotectonic and neotectonic control on river pattern in the Sierra de la Cantera piedmont, central Precordillera, province of San Juan, Argentina

PERUCCA; ROTHIS, M; VARGAS, N

GEOMORPHOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2013

0169-555X

The drainage pattern on the western piedmont of the Sierra de La Cantera isdivergent, typical of alluvial fans and showing anomalies that are directly related tothe trace of La Cantera thrust. In previous studies, two types of anomalies wereidentified: upstream of the fault scarp, rivers have a broom-shaped pattern, whiledownstream -in the hanging block- streams become denser, more sinuous andincised. In this contribution, these morphotectonic aspects were analyzed in detail,making direct and indirect analysis to quantify the relationship between theseanomalies and the faults affecting alluvial fans. In addition, the influence ofneotectonic activity on smaller water course patterns in the alluvial fan areas wasinvestigated in order to find indicators of on-going vertical movements, since thespatial arrangements of these piedmont channels are determined by slope andstructure, where active faults cause diversions or anomalies. Topographic profiles intwo selected channels cutting across the trace of the fault were performed using adifferential GPS in order to establish the relationship between the sinuosity andslope of these rivers. The results obtained allow us to state that the most sinuouschannels have lower slopes and are located in the hanging wall of the fault.