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

摘要

The contribution of landslides to the Quaternary evolution of relief ispoorly documented in arid contexts. In southern Peru and northern Chile,several massive landslides disrupt the arid western Andean front. TheChuquibamba landslide, located in southern Peru, belongs to this set oflarge landslides. In this area, the Incapuquio fault system captures theintermittent drainage network and localizes rotational landslides. Seismicactivity is significant in this region with recurrent M_w 9 subductionearthquakes; however, none of the latest seismic events have triggered amajor landslide. New terrestrial cosmogenic dating of the Chuquibambalandslide provides evidence that the last major gravitational mobilizationof these rotational landslide deposits occurred at ~ 102 ka,during the Ouki wet climatic event identified on the Altiplano between 120and 98 ka. Our results suggest that wet events in the arid and fracturedcontext of the Andean forearc induced these giant debris flows. Finally, ourstudy highlights the role of tectonics and climate on (i) the localizationof large Andean landslides in the Western Cordillera and on (ii) thelong-term mass transfer to the trench along the arid Andean front.