Assessing the last “large scale fluvial modification” across the hyperarid Atacama Desert, northern Chile

Abstract

During the last decade, a consensus has been widely established about an Early Miocene onset of hyperaridity characterizing the Atacama Desert located in the Andean forearc region in northern Chile. Prevailing hyperarid conditions were interrupted by many pluvial episodes of varying duration and spatial extent. In contrast to the onset of hyperaridity, highly discrepant interpretations persist regarding the last “large scale fluvial modification” (Ritter et al., 2018) of the Atacama Desert. While terminal aggradation of the coastal alluvial fans is constrained at several sites to the Last Glacial Maximum (MIS 2), followed by Holocene progradation to the shore, chronological constraints for last major fluvial activity throughout the inland desert scatter between the Late Miocene and Middle Pleistocene. The types of investigated sedimentary archives differ and many studies have a local focus. Instead, a systematic assessment from the hyperarid coast (W) to the footslopes of the Precordillera (E) is yet lacking. We therefore mapped 84 alluvial fan systems with small (

Authors 8

1. Janek Walk corresponding Aachen Department of Geography

   University of Vienna · RWTH Aachen University

   Affiliation as printed

   Department of Geography and Regional Research, University of Vienna, Vienna, Austria (janek.walk@univie.ac.at)

   Department of Geography, RWTH Aachen University, Aachen, Germany

2. Joel Mohren corresponding Aachen Department of Geography

   University of Cologne · RWTH Aachen University

   Affiliation as printed

   Department of Geography, RWTH Aachen University, Aachen, Germany

   Institute of Geology and Mineralogy, University of Cologne, Cologne, Germany

3. Ariane Binnie corresponding Aachen Institute of Neotectonics and Natural Hazards

   University of Cologne · RWTH Aachen University

   Affiliation as printed

   Institute of Geology and Mineralogy, University of Cologne, Cologne, Germany

   Institute of Neotectonics and Natural Hazards, RWTH Aachen University, Aachen, Germany

4. Dominik Brill corresponding

   University of Cologne

   Affiliation as printed

   Institute of Geography, University of Cologne, Cologne, Germany

5. Helmut Brückner

   University of Cologne

   Affiliation as printed

   Institute of Geography, University of Cologne, Cologne, Germany

6. Viktor Schaubert Aachen Department of Geography

   RWTH Aachen University

   Affiliation as printed

   Department of Geography, RWTH Aachen University, Aachen, Germany

7. Andrés Quezada

   Servicio Nacional de Geologia y Mineria

   Affiliation as printed

   Servicio Nacional de Geología y Minería, Santiago, Chile

8. Frank Lehmkuhl corresponding Aachen Department of Geography

   RWTH Aachen University

   Affiliation as printed

   Department of Geography, RWTH Aachen University, Aachen, Germany