Pedogenesis at the coastal arid-hyperarid transition deduced from a Late Quaternary chronosequence at Paposo, Atacama Desert

Autor(en)

Janek Walk, Philipp Schulte, Melanie Bartz, Ariane Binnie, Martin Kehl, Ramona Mörchen, Xiaolei Sun, Georg Stauch, Christopher Tittmann, Roland Bol, Helmut Brückner, Frank Lehmkuhl

Abstrakt

Under hyperarid climate conditions, pedogenesis is driven by the atmospheric deposition and subsequent accumulation of easily to moderately soluble salts forming extreme types of Aridisols. In contrast, the processes and timescales of soil formation in coastal desert environments are as yet not well understood. Therefore, a soil chronosequence at the arid-hyperarid transition in the south-central coastal Atacama Desert is investigated. We measured physicochemical soil parameters of shallow soil profiles on four generations of a multi-stage alluvial fan system, assisted by micromorphological analysis, allowing to deduce the soil-forming processes. We further established a geochronological framework by applying

¹⁰Be cosmogenic nuclide exposure dating on the abandoned surface generations, which allowed to infer the timescales for soil formation. The results indicate initial yet clearly identifiable pedogenesis occurring since MIS 5e–c. Along the Late Quaternary chronosequence, physicochemical soil properties show decreasing trends with growing age for the median grain size, salinity, long-term pH development, and CaCO

₃ contents. Contrarily, organic carbon, the ratio of organic to total phosphorus, the redness, and the contents of total and poorly crystalline pedogenic iron oxides tend to increase with age. This provides evidence for soil formation under an arid to hyperarid coastal climate characterized by (i) redistribution of salts by leaching causing topsoil desalinization; (ii) decalcification coupled with (iii) dealkalinization in totally decalcified horizons; (iv) accumulation of soil organic matter; (v) initial rubification through formation of pedogenic iron oxides (i.e. hematite); and (vi) initial loamification that, in turn, might have impeding effects on the translocation of soil constituents on timescales larger than 10

⁵ a. Furthermore, in situ pedogenesis might be superimposed considerably by aeolian dust influx. At Atacama's south-central coast, the state of pedogenic alteration scales with the cumulative precipitation received throughout the entire Late Quaternary, yet evolved strongest between MIS 5 and the MIS 4/3-transition.

Organisation(en)

Institut für Geographie und Regionalforschung

Externe Organisation(en)

Rheinisch-Westfälische Technische Hochschule Aachen, Universität zu Köln, Université de Lausanne, Rheinische Friedrich-Wilhelms-Universität Bonn, Forschungszentrum Jülich

Journal

CATENA

Band

228

Anzahl der Seiten

21

ISSN

0341-8162

DOI

https://doi.org/10.1016/j.catena.2023.107171

Publikationsdatum

07-2023

Peer-reviewed

Ja

ÖFOS 2012

105402 Bodengeographie, 105127 Geochronologie, 401902 Bodenkunde, 105404 Geomorphologie

Schlagwörter

ASJC Scopus Sachgebiete

Earth-Surface Processes

Sustainable Development Goals

SDG 13 – Maßnahmen zum Klimaschutz

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/94714cf1-5fd6-4c08-ae53-ef4d2766a849