Increased hillslope activity in the hyper‐arid core of the Atacama during the Pleistocene – evidence for palaeo‐climatic fluctuations?
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| Title: | Main Title: Increased hillslope activity in the hyper‐arid core of the Atacama during the Pleistocene – evidence for palaeo‐climatic fluctuations? |
| Description: | Abstract: Hillslopes represent areas of predominant denudation and constitute the transition and trajectory to floodplains; they play a crucial role in understanding the long-term landscape evolution of desert environments. However, although hillslope processes are known to be very slow or even stagnant in (hyper-)arid environments, process mechanisms under the absence of water are poorly understood, and process rates are essentially unknown. Therefore, sub-project C03 of the DFG-funded Collaborative Research Centre 1211 (CRC 1211) “Earth – Evolution at the dry limit” is dedicated to the investigation of hillslope processes in the (hyper-)arid zones of the Atacama Desert. It aims at contributing to a better understanding of controls and processes of hillslope dynamics in the driest parts of the earth on both recent and geological time scales using a variety of different methods. Based on irrigation experiments, different monitoring techniques, geomorphological, stratigraphical, geochronological, sedimentological and geochemical investigations, as well as µCT scans of sediment cores, this contribution presents detailed insights into the chronostratigraphy of tongue-shaped, 70 m-long and 30 m-wide fine sediment lobes located along a 10-20° steep thrust-related slope east of the Salar Grande (Atacama, Chile). Irrigation experiments were performed in order to gain insights into precipitation thresholds for surface runoff and hillslope dynamics using a simple and portable irrigation device, carrying spraying nozzles in 2 m height over the 2 x 5 m irrigation plot. Uniformity coefficients of ~86 % (1 bar, 12 l/min, six nozzles) and ~74 % (0.5 bar, 10.5 l/min, eight nozzles, increased drop sizes) document rather homogeneous rainfall distributions. Although artificial rainfall intensities were ~46 l/m²/h, infiltration was 100 %, and none of the experiments initiated surface runoff or (detectable) slope material displacements. However, we detected a statistically significant increase in post-irrigation TOC concentrations in the moist sediment layers, i.e. the uppermost ~15 cm of the irrigated sediment. In addition, a distinct stratigraphic pattern with buried palaeo-surfaces and palaeo-biological surface crusts suggests increased slump-, creep-, or solifluction-like hillslope activity during the Pleistocene, potentially driven by changes of (fog-induced) humidity, salt and gypsum shrink and swell processes, or palaeo-seismicity. While a variety of geo-bio-archives document periods of increased precipitation in the Andean parts of the Atacama Desert throughout the quaternary, evidence for contemporaneous paleoclimatic changes from areas disconnected to Andean precipitation fluctuations (i.e., the coastal cordillera) is scarce. In this regard, the investigated landforms potentially represent one of only few sediment records recording paleoclimatic changes in the central desert, independent from Andean rainfall. |
Responsible Party
| Creators: | Matthias May (Author), Dirk Hoffmeister (Author), Dominik Brill (Author), Alicia Medialdea (Author), Marie Gröbner (Author), Florian Steininger (Author), Lennart Meine (Author), Ramona Mörchen (Author), Eva Lehndorff (Author), Maxim Deprez (Author), Tim de Kock (Author), Olaf Bubenzer (Author) |
| Publisher: | CRC1211 Database (CRC1211DB) |
| Publication Year: | 2019 |
Topic
| CRC1211 Topic: | Surface |
| Related Subproject: | C3 |
| Subject: | Keyword: Geomorphology |
| Geogr. Information Topic: | Environment |
File Details
| Filename: | MayetalAKGeomorph2018Poster.pdf |
| Data Type: | Event - Event |
| File Size: | 2.2 MB |
| Date: | Available: 31.10.2018 |
| Mime Type: | application/pdf |
| Data Format: | |
| Language: | English |
| Status: | Completed |
Constraints
| Download Permission: | Only Project Members |
| General Access and Use Conditions: | According to the CRC1211DB data policy agreement. |
| Access Limitations: | According to the CRC1211DB data policy agreement. |
| Licence: | [CRC1211DB] Data policy agreement |
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Specific Information - Presentation
| Presenter: | Simon Matthias May |
| Presentation Date: | 25th of September, 2018 |
| Presentation Type: | Poster |
| Event: | Central European Conference on Geomorphology and Quaternary Sciences |
| Event Type: | Conference |
| Event Location: | Giessen, Germany |
| Event Duration: | 23rd of September, 2018 - 27th of September, 2018 |
| Event Website: | http://www.uni-giessen.de/fbz/fb07/fachgebiete/geographie/bereiche/physisch/akg-deuqua2018 |
Metadata Details
| Metadata Creator: | Simon Matthias May |
| Metadata Created: | 28.10.2019 |
| Metadata Last Updated: | 28.10.2019 |
| Subproject: | C3 |
| Funding Phase: | 1 |
| Metadata Language: | English |
| Metadata Version: | V50 |
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| Metadata Downloads: | 0 |
| Dataset Downloads: | 1 |
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