2026-05-28T17:25:41Zhttp://doidb.wdc-terra.org/oaip/oai

oai:doidb.wdc-terra.org:85702025-10-06T10:00:54ZDOIDBDOIDB.CRC1211

false4DOIDB.CRC1211 10.5880/CRC1211DB.88 Wennrich, Volker Volker Wennrich University of Cologne, Institute of Geology and Mineralogy Diederich-Leicher, Julia Julia Diederich-Leicher University of Cologne, Institute of Geology and Mineralogy Ritter, Benedikt Benedikt Ritter University of Cologne, Institute of Geology and Mineralogy Copernicus 2025 Climatology/Meteorology/Atmosphere Paleoclimate Proxies Drill Core Diederich-Leicher, Julia Julia Diederich-Leicher University of Cologne, Institute of Geology and Mineralogy Blanco, Barbara Barbara Blanco University of Cologne, Institute of Geophysics and Meteorology Büttner, Christoph Christoph Büttner TU Bergakademie Freiberg, Institute of Geophysics and Geoinformatics Buske, Stefan Stefan Buske TU Bergakademie Freiberg, Institute of Geophysics and Geoinformatics Campos, Eduardo Eduardo Campos Universidad Católica del Norte, Departamento de Ciencias Geológicas Dunai, Tibor Tibor Dunai University of Cologne, Institute of Geology and Mineralogy Feller, Jacob Jacob Feller University of Cologne, Institute of Geology and Mineralogy Fernández-Galego, Emma Emma Fernández-Galego University of Cologne, Institute of Geology and Mineralogy Hasberg, Ascelina Ascelina Hasberg University of Cologne, Institute of Geology and Mineralogy Leicher, Niklas Niklas Leicher University of Cologne, Institute of Geology and Mineralogy López, Damián Alejandro Damián Alejandro López University of Cologne, Institute of Geology and Mineralogy Maldonado, Jorge Jorge Maldonado Superex S.A. Diamond and Sonic Drilling Group, Santiago, Chile Medialdea, Alicia Alicia Medialdea University of Cologne, Institute of Geography Ninnemann, Lukas Lukas Ninnemann TU Bergakademie Freiberg, Institute of Geophysics and Geoinformatics Perryman, Russell Russell Perryman Comprobe, Borehole Imaging and Orientation Services Ríos Contesse, Juan Cristóbal Juan Cristóbal Ríos Contesse Universidad Católica del Norte, Departamento de Ciencias Geológicas Ritter, Benedikt Benedikt Ritter University of Cologne, Institute of Geology and Mineralogy Scheidt, Stephanie Stephanie Scheidt University of Cologne, Institute of Geology and Mineralogy Vargas-Machuca, Barbara Barbara Vargas-Machuca University of Cologne, Institute of Geology and Mineralogy Yogeshwar, Pritam Pritam Yogeshwar University of Cologne, Institute of Geophysics and Meteorology Melles, Martin Martin Melles University of Cologne, Institute of Geology and Mineralogy Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659 CRC 1211 Earth - Evolution at the Dry Limit 04.07.2025 en Paper Preprint 10.5880/CRC1211DB.86 10.5880/CRC1211DB.87 10.5880/CRC1211DB.89 10.5880/CRC1211DB.86 10.5880/CRC1211DB.87 10.5880/CRC1211DB.89 PDF 1 [CRC1211DB] Data policy agreement The Atacama Desert is one of the driest deserts on Earth with a predominantly hyperarid climate at least since the Miocene. Geological evidence, however, indicates that this overall hyperaridity was repeatedly interrupted by wetter periods. Deep-time precipitation reconstructions of the Atacama Desert are limited by scarce and discontinuous sediment sequences, most of which received moisture from wetter regions outside the Atacama Desert. Longer archives of the precipitation history in the desert interior during the Neogene are unfortunately extremely rare. The sediment records of two tectonically blocked endorheic basins (a.k.a clay pans) in the Coastal Cordillera of northern Chile may fill the gaps in the paleo-precipitation record of the Atacama Desert. Comprehensive investigations of both clay pans applied intensive geological and geophysical site surveys and deep drilling operations with subsequent downhole logging. Short pilot cores of up to 6.2 m in length already showed highly variable sediment successions reflecting strong hydroclimatic fluctuations on glacial/interglacial timescales. Electromagnetic and seismic surveys yielded a three-layer structure in both basins consisting of the resistive basement overlain by a low-resistivity basal and a highly resistive upper sediment unit with total sediment thicknesses of more than ∼100 and ∼160 m in the Playa Adamito Grande (PAG) and Paranal clay pans, respectively. Assuming similar sedimentation rates as the pilot cores, this would imply that the sediment records of both clay pans span several million years. Lithological data and downhole-logging results of the deep-drilling operations reveal strong heterogeneities in the sediment composition that presumably can be traced back to major climatic and/or tectonic shifts in the catchments of the clay pans. Whereas the fine-grained sediments at the base of the PAG sequence suggest longer-lasting lacustrine sedimentation with enhanced evaporative episodes, the lower sediment package in the core from the Paranal clay pan consists of fluvial conglomerates and sandstones. Both lacustrine and fluvial sediments indicate less arid conditions in the central Atacama Desert than today. Separated by distinct lithological boundaries, the upper sediments in both clay pans show several similar sediment facies typical for alluvial-fan deposition, e.g., proximal mud and debris flows, sheetfloods, and distal alluvial sediment flows, but also pedogenic calcium sulfates. The shift to a predominant alluvial-fan deposition, which is common after torrential rainfall in the Atacama Desert today, implies a general modification in the environmental conditions of the study areas. These initial results already highlight the potential of the sediment records from the PAG and Paranal clay pans to provide unprecedented information on the Neogene precipitation history in the hyperarid core of the Atacama Desert. Southern Focus Area, Chile -69.9135685 -21.5421551 Southern Focus Area, Chile -70.1485203 -24.4874369