Pedogenesis under coastal hyperaridity – Soil formation since the Middle Pleistocene at Paposo, Atacama Desert, northern Chile

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Title:Main Title: Pedogenesis under coastal hyperaridity – Soil formation since the Middle Pleistocene at Paposo, Atacama Desert, northern Chile
Description:Abstract: Soil formation under hyperaridity is strongly limited by the availability of water, biotic activity, and unfavourable soil properties, resulting in a group of taxa subsumed under Aridisols according to the USDA soil taxonomy. In case of the Atacama Desert, previous studies have focussed on soils with salic, gypsic, or nitric characteristics in the hyperarid core of the desert. In contrast, and although also classified as hyperarid, the coast of the Atacama Desert receives much larger amounts of moisture, mainly due to advective fog blocked by the Coastal Cordillera in elevations between ~500 and ~1,200 m above sea level. In close association with the fog, Loma vegetation, which combs out precipitation equivalents of several hundreds of mm/a, populates the western Coastal Cordillera. However, neither the properties, the responsible processes nor the timescales on which the coastal soils were formed have as yet been investigated. We therefore assessed physical and chemical soil parameters at an alluvial fan system at Paposo and deduced from them the pedogenetic processes. Four upper soil profiles were sampled from each of the four alluvial fan generations: three successively abandoned units that were also dated by cosmogenic Beryllium-10 exposure dating as well as the active surface. By establishing a morphochronology of the fan system’s evolution, the rates of soil formation under coastal hyperaridity can be derived. The results show mostly monotonic relationships of physicochemical soil properties with increasing time since abandonment of the first fan surface in the Mid-Pleistocene. The altering effects of mainly physical but to some degree also chemical weathering on the soil texture are reflected by a continuous fining towards older soils. Spectroscopic analysis of the soil colour as well as the geochemistry of pedogenetic iron oxides suggest a significant contribution of rubification. That chemical weathering plays an important role, is further supported by different indices derived from bulk geochemistry. Moreover, complete decalcification of the two oldest surface generations is apparent. In contrast, differences in the cumulative effect of biotic activity shown in the organic carbon content as well as plant nutrients adsorbed to different colloids is characterized by a high spatial and temporal variability.
Responsible Party
Creators:Janek Walk (Author), Christopher Tittmann (Author), Ramona Mörchen (Author), Xiaolei Sun (Author), Melanie Bartz (Author), Philipp Schulte (Author), Steven Binnie (Author), Georg Stauch (Author), Roland Bol (Author), Helmut Brückner (Author), Frank Lehmkuhl (Author)
Funding Reference:Deutsche Forschungsgemeinschaft (DFG): CRC 1211: Earth - Evolution at the Dry Limit
Publisher:CRC1211 Database (CRC1211DB)
Publication Year:2021
CRC1211 Topic:Surface
Related Subproject:C2
Subjects:Keywords: Soil Sciences, Biogeochemistry of Soils, Geochronology, Cosmogenic Nuclides, Arid Zone, Geomorphology
Geogr. Information Topic:Environment
File Details
Data Type:Text - Text
File Size:75 MB
Date:Created: 03.11.2021
Mime Type:application/pdf
Data Format:PDF
Download Permission:Only Project Members
General Access and Use Conditions:According to the CRC1211DB data policy agreement. © Author(s) 2021.
Access Limitations:According to the CRC1211DB data policy agreement. © Author(s) 2021.
Licence:[CRC1211DB] Data policy agreement
Specific Information - Presentation
Presenter:Janek Walk
Presentation Date:6th of November, 2021
Presentation Type:Poster
Event:Mid-European Geomorphology Meeting (MGM) 2021
Event Type:Conference
Event Location:München
Event Duration:6th of November, 2021 - 9th of November, 2021
Event Website:
Metadata Details
Metadata Creator:Janek Walk
Metadata Created:18.11.2021
Metadata Last Updated:18.11.2021
Funding Phase:2
Metadata Language:English
Metadata Version:V50
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