Slope and climate variability control of erosion in the Andes of central Chile

Abstract

Artículo de publicación ISIClimate and topography control millennial-scale mountain erosion, but their relative impacts remain matters of debate. Confl icting results may be explained by the infl uence of the erosion threshold and daily variability of runoff on long-term erosion. However, there is a lack of data documenting these erosion factors. Here we report suspended-load measurements, derived decennial erosion rates, and 10Be-derived millennial erosion rates along an exceptional climatic gradient in the Andes of central Chile. Both erosion rates (decennial and millenial) follow the same latitudinal trend, and peak where the climate is temperate (mean runoff ~500 mm yr–1). Both decennial and millennial erosion rates increase nonlinearly with slope toward a threshold of ~0.55 m/m. The comparison of these erosion rates shows that the contribution of rare and strong erosive events to millennial erosion increases from 0% in the humid zone to more than 90% in the arid zone. Our data confi rm the primary role of slope as erosion control even under contrasting climates and support the view that the infl uence of runoff variability on millennial erosion rates increases with aridity

Tectonic controls of Holocene erosion in a glaciated orogen

“…In tectonically active and previously glaciated mountain ranges there are three common orogenic processes that are most often suggested to dominate Holocene erosion rate patterns: climate gradients (Carretier et al, 2013;Olen et al, 2016), glacial modification of the landscape (Moon et al, 2011;Glotzbach et al, 2013), and patterns of tectonic rock uplift (Scherler et al, 2013;Godard et al, 2014;Adams et al, 2016). In the following we explore the relevance and applicability of these explanations to our dataset.…”

Tectonic and climatic controls on the Chuquibamba landslide (western Andes, southern Peru)

“…As rare and strong erosive events represent the most important contribution to the long-term erosion of the arid Western Cordillera (Carretier et al, 2013), we propose that events like the Chuquibamba landslide contribute significantly to the long-term erosion of the western escarpment of the Andes. We thus suggest a strong regional tectonic and climatic control of the long-term erosion of the arid western Andean front.…”

“…Moreover, the Altiplano has been the target of many paleoclimatic investigations (Thompson et al, 1998(Thompson et al, , 2000Cross et al, 2001;Baker et al, 2001;Placzek et al, 2006Placzek et al, , 2013 that highlighted climate fluctuations for the last 130 kyr. Steffen et al (2009Steffen et al ( , 2010, Carretier et al (2013) and Bekaddour et al (2014) highlighted the contribution of these wet climatic events to mass transport in major canyons from the Altiplano to the Pacific coast. In contrast, McPhillips et al (2014) observed that the landslide frequency appears to have not changed during the Quaternary and thus questioned the impact of the climatic fluctuations on landsliding and erosion rate.…”

“…We suggest that the Ouki event was the latest event whose duration and intensity was sufficient to trigger a large landslide in the arid western Andean flank (Wörner et al, 2002;Strasser and Schlunegger, 2005;Blard et al, 2009). Carretier et al (2013) proposed that rare and strong erosive events contribute to more than 90 % of the long-term erosion of the arid western side of the Andean range. Accordingly, we suggest that climatic fluctuations that favor landsliding, such as the Ouki wet event, have a great impact on sediment transport and morphologic evolution of the western flank of the Andes.…”

Autogenic versus allogenic controls on the evolution of a coupled fluvial megafan–mountainous catchment system: numerical modelling and comparison with the Lannemezan megafan system (northern Pyrenees, France)

“…Bookhagen et al, 2005), although their relationship to other environmental parameters, such as vegetation cover, remains disputed (e.g. Istanbulluoglu and Bras, 2005;Carretier et al, 2013;Dosseto and Schaller, 2016). Our current model does not to take such processes into account.…”