Late Pleistocene fans and terraces in the Majes valley, southern Peru, and their relation to climatic variations

This study investigates the connection between sediment aggradation, erosion and climate in a desert environment of the Males valley, southern Peru Luminescence dating of terraces and fans shows that sediment aggradation correlates with wet time intervals on the Altiplano, suggesting a climatic influence on the aggradation-degradation cycles Major periods of aggradation occurred between similar to 110-100, similar to 60-50 and 12-8 ka More precipitation in the Males catchment resulted in increased erosion and transportation of sediment from the hillslopes into the trunk river As a result, the sediment loads exceeded the transport capacity of the Males River and aggradation started in the lower reaches where the river gradient is less Depletion of the hillslope sediment reservoirs caused a relative increase in the capacity of the trunk river to entrain and transport sediment, resulting in erosion of the previously deposited sediment Consequently, although climate change may initiate a phase of sediment accumulation, degradation can be triggered by an autocyclic negative feedback and does not have to be driven by climatic change