Erosion rates in the transition between the Central and Patagonian Andes, Argentina.The importance of landsliding as erosion process in active orogenic fronts.

PENNA, I.M.; HERMANNS, R.L.; DAICZ, S.

Cuzco

Congreso; XV Congreso Peruano de Geología; 2010

Sociedad Geológica del Perú

In the past years, numerous studies focused on the influence of the interaction between climate, tectonics and surface processes in the modeling of mountain ranges (Burbank et al., 1996; Montgomery et al., 2001). The knowledge of the relationship between erosion rates and structural evolution of orogens has substantially increased. Important studies such as the one performed by Strecker et al. (2007) discussed the close link between rainfall patterns, tectonic deformation and erosion in the Central Andes. Glacial and fluvial erosion are usually considered as the main promoters of orogenic degradation, while mass wasting phenomena is conceived a subordinate process. However, Montgomery and Brandon (2002), by analyzing different orogenic chains, observed that the uplift in tectonically active areas increase the frequency of slope collapses and Capolongo and Schiattarella (2005) show in the Apennines that large landslides triggered by earthquakes are main agents of erosion. In this work we analyze the magnitude with which glacial, fluvial and mass wasting processes contribute to the shaping of the eastern slope of the Andes between 37º-37.5º S. In this area, located in the transition between the Central and Patagonian Andes, fluvial and glacial action has incised intensively a Plio-Pleistocene volcanic plateau (Cola de Zorro Formation, Vergara and Munoz, 1982), developed on Oligo-Miocene rocks belonging to the Cura Mallin basin (Jordan et al., 2001).