Geomorphology of the coastal alluvial fan complex Guanillos, northern Chile

Abstract

The evolution of alluvial fans on the narrow coastal plain of the Atacama Desert in northern Chile is so far poorly investigated. Therefore, a detailed geomorphological map at a scale of 1:7500 of a coastal alluvial fan complex at Guanillos (21°58′S, 70°10.5′W) is provided as a first step to understand the fan’s morphogenesis. Geomorphological mapping was based on a digital elevation model with a resolution of 2 m generated from Pleiades-1 tri-stereo satellite imagery, derived terrain parameters, and on-site field mapping. The resultant map is used to characterize and categorize the overall morphology of the alluvial fan complex. In particular, linear features constructed by primary alluvial fan processes can be differentiated successfully from those developed by secondary processes. Furthermore, the advanced evolutionary state of the fan complex is revealed. We introduce a morphostratigraphic model comprising the fan’s prograde evolution, dissection, and successive abandonment of surface generations.

Keywords

• geomorphological map
• alluvial fan
• pleiades
• northern chile
• atacama desert
• coastal cordillera