Abstract

BANCHIG, Aldo Luis; MOREIRAS, Stella Maris  and  BANCHIG, Paolo Nahuel. Avalanches and dammed valleys events of Prehistoric occurrence in the Villavil river basin, Sierra de Aconquija, Andalgalá, Catamarca. Rev. Asoc. Geol. Argent. [online]. 2009, vol.65, n.4, pp.805-814. ISSN 0004-4822.

The study reports reactivations of an ancient rock avalanche (2.69 x10⁹ m³) generated in the eastern hillslope of Zapallar peak (3,100 m a.s.l.) in the southern sector of Sierra del Aconquija (Sierras Pampeanas). Multiple events of the original deposit have generated several natural dams in the Villavil river. The area is located in basement outcrops constituted by granites crossed by two regional faults that favored the occurrence of these events. Evidence of Quaternary activity of these regional faults suggests a seismic triggering mechanism associated with these structures even though this hypothesis is not supported by seismic historical records. The occurrence of these successive collapses related to damned paleo-lakes along the Villavil river is a potential risk for the developiment of Villavil village located in this gully.

Keywords : Aconquija; Villavil river; Rock avalanche; Geological risk; Neotectonics.

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