Neotectonic controls and stream piracy on the evolution of a river catchment: a case study in the Agua de la Peña River basin, Western Pampean Ranges, Argentina

PERUCCA, LAURA P.; ESPEJO, KAREN; ESPER ANGILLIERI, MARÍA YANINA; ROTHIS, MARTÍN; TEJADA, FLAVIA; VARGAS, MARIANA

JOURNAL OF IBERIAN GEOLOGY

SERVICIO PUBLICACIONES

Año: 2018

1698-6180

Purpose The La Peña River basin is located to the northeast of the province of San Juan, and crosses from east to west, the entire northern portion of the sierra de Valle Fértil, in Western Pampean Ranges. The strong relief of the mountain range is attributed to neotectonic activity of the NW trending Valle Fértil fault. The purpose of this study is to interpret the geologicalcontrol on the dynamic drainage organization and the relevant neotectonic tilt due to the above-mentioned fault and to the NE trending El Alto fault. In addition, to identify stream piracy due to neotectonic activity of the Valle Fértil and El Alto faults in this river basin.Method We analyze the influence of tectonics in the evolution and shaping up of the present day Agua de La Peña River drainage basin, using geomorphic indices and markers. Several morphotectonic parameters obtained for the Agua de La PeñaRiver basin allow us to determine the inference of tectonic deformation along the river profile. The regional morphometric analysis relies on four topographical swath profiles to identify several regional topographic features and anomalies. We examine the main river channel and tributaries in terms of their longitudinal profiles and knickpoints distribution in order to explore the signal of transient geomorphic response to river capture.Results Our results show the main control of neotectonics on the local topography and drainage network. Based on the foregoing, we infer that the landscape in northern portion of sierra de Valle Fértil is in a transient state derived from a combination between drainage arrangement and relief rejuvenation, and so, river basin features are mainly caused by divide migration, drainage network adjustments and catchment capture due to neotectonism. It may result from the tectonic adjustment of Valle Fértil and El Alto faults since the Pleistocene until the present day.Conclusion We conclude that reorganization of drainage lines by capture and reversal drainage by neotectonic activity could explain the unusual pattern of this river basin