Deutsch Intern
Chair of Geomorphology

CRC 1211 – C02 – Transport and deposition

Formation of alluvial fans and their geo-bio-archive function under hyperaridity – Integrating empiricism and landscape evolution modelling

Due to the direct coupling of alluvial fans (AF) to the source area, they present quintessential depositional features and preserve responses of the sediment routing systems to palaeoclimatic variability, tectonic activity and base-level changes in their architecture and stratigraphy. However, the impact of autogenic controls governing the AF internal dynamics make it challenging to decipher these allogenic environmental controls. AF are widespread in the Atacama Desert from its arid margins to its hyperarid core and, thus, provide great potential to link and compare these morphodynamic systems with other existing regional palaeoenvironmental archives – of which many have been and are planned to be further investigated within the CRC 1211. Informed by the results of the previous phases, the following overarching research questions will be pursued:

  1. How is the impact of autogenic and environmental (allogenic) controls reflected in the variability of AF structure under transport- versus sediment-supply (under-capacity) limitation – and are consequently governing AF ecological habitat function in the Atacama Desert?
  2. How does fan evolution under (hyper)aridity affect the propagation of climatic, biotic and geologic source-area signals and their preservation in fan stratigraphy – and thus impact the potential of AF as Quaternary and Neogene palaeoenvironmental archives for the Atacama Desert?

Braun (2022) has contrasted two fundamental approaches for modelling fan evolution (transport-limitation versus under-capacity), that are characterized by different internal fan structures and building times needed to reach a steady state. A synthesis of empirical data on AF and source-area morphology, stratigraphy and timing in the Atacama Desert assessed during the first and second phases of the CRC 1211 (Bartz et al., 2020a, 2020b; Walk et al., 2019, 2020, 2022, 2023), complemented by well-directed analysis of additional AF at strategic locations, will be used to parametrize and validate the different physics-based numerical approaches. This will provide critical insights on (i) which approach is best suited for replicating the evolution of AF under different climatic and tectonic conditions and (ii) a better understanding of the AF environment and thus a basis for the interpretation of fan (morpho)stratigraphic records. The approach will be applied along a longitudinal environmental gradient across the Atacama Desert extended to the arid Altiplano. This aims at deciphering the impacts of different allogenic controls on fan evolution from autogenic ones under real conditions – a challenging objective that is hard to achieve exclusively by modelling or empiricism. A better understanding of the geomorphic fan evolution will further allow to study in a close bio-geo-collaboration their potential as “habitats and pathways of life” under water limitation.

Publications (since first project phase)

Bartz, M., Duval, M., Brill, D., Zander, A., King, G.E., Rhein, A., Walk, J., Stauch, G., Lehmkuhl, F., Brückner, H., 2020a. Testing the potential of K-feldspar pIR-IRSL and quartz ESR for dating coastal alluvial fan complexes in arid environments. Quaternary International 556, 124–143. https://doi.org/10.1016/j.quaint.2020.03.037

Bartz, M., Walk, J., Binnie, S.A., Brill, D., Stauch, G., Lehmkuhl, F., Hoffmeister, D., Brückner, H., 2020b. Late Pleistocene alluvial fan evolution along the coastal Atacama Desert (N Chile). Global and Planetary Change 190, 103091. https://doi.org/10.1016/j.gloplacha.2019.103091

Sun, X., Amelung, W., Klumpp, E., Walk, J., Mörchen, R., Böhm, C., Moradi, G., May, S.M., Tamburini, F., Wang, Y., Bol, R., 2024. Fog controls biological cycling of soil phosphorus in the Coastal Cordillera of the Atacama Desert. Global Change Biology 30, e17068. https://doi.org/10.1111/gcb.17068

Walk, J., 2020. Alluvial fans along the coastal Atacama Desert – landforms, processes, and evolution. Dissertation), Rheinisch-Westfälische Technische Hochschule Aachen, Aachen, S. 165. https://doi.org/10.18154/RWTH-2020-06003

Walk, J., Bartz, M., Stauch, G., Binnie, A., Brückner, H., Lehmkuhl, F., 2022. Weathering under coastal hyperaridity – Late Quaternary development of spectral, textural, and gravelometric alluvial fan surface characteristics. Quaternary Science Reviews 277, 107339. https://doi.org/10.1016/j.quascirev.2021.107339

Walk, J., Schulte, P., Bartz, M., Binnie, A., Kehl, M., Mörchen, R., Sun, X., Stauch, G., Tittmann, C., Bol, R., Brückner, H., Lehmkuhl, F., 2023. Pedogenesis at the coastal arid-hyperarid transition deduced from a Late Quaternary chronosequence at Paposo, Atacama Desert. CATENA 228, 107171. https://doi.org/10.1016/j.catena.2023.107171

Walk, J., Stauch, G., Bartz, M., Brückner, H., Lehmkuhl, F., 2019. Geomorphology of the coastal alluvial fan complex Guanillos, northern Chile. Journal of Maps 15, 436–447. https://dx.doi.org/10.1080%2F17445647.2019.1611499

Walk, J., Stauch, G., Reyers, M., Vásquez, P., Sepúlveda, F.A., Bartz, M., Hoffmeister, D., Brückner, H., Lehmkuhl, F., 2020. Gradients in climate, geology, and topography affecting coastal alluvial fan morphodynamics in hyperarid regions – The Atacama perspective. Global and Planetary Change 185, 102994. https://doi.org/10.1016/j.gloplacha.2019.102994