Abstract

The Quaternary development of the Pisco valley in central Peru has been characterized by multiple phases of sediment accumulation and erosion that formed distinct levels of cut-and-fill terraces and alluvial fans. Luminescence dating shows that they formed in response to at least two different stages of sediment accumulation and erosion during the past 60 ka, the main phase of sediment aggradation occurring between ca. 54 and 38 ka ago. The ages show that sediment accumulation was contemporaneous with the time intervals of the Minchin (47.8–36 ka ago, with enhanced precipitation beginning ca. 54.8 ka ago) and Tauca (26–14.9 ka ago) paleolakes on the Altiplano, where the headwaters of the Pisco River are located. We conclude that sediment accumulation was triggered by shifts toward a more humid climate, whereas erosion is the response of the fluvial system to the depletion of the hillslope sediment reservoirs.

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