Weathering under coastal hyperaridity – Late Quaternary development of spectral, textural, and gravelometric alluvial fan surface characteristics

A power-law relation of surface roughness and ages of alluvial fans in a hyperarid environment: A case study in the Dead Sea area

“…The depositional landforms primarily respond to external forcings (e.g., tectonics, climate, and base-level change) that typically dominate the evolution of alluvial fans (Waters et al, 2010; Fidolini et al, 2013; Davis et al, 2021). Mapping and dating alluvial fans are critical to disentangle the response of geomorphic evolution to external forcings and highlight the need for analytical tools that can quickly determine the spatial distributions and the relative ages of different morphostratigraphic units (Stock et al, 2013; Harvey, 2018; Walk et al, 2022). Among techniques that have been used for such purpose, remote sensing techniques (Frankel and Dolan, 2007; Zhang and Guo, 2013; Regmi et al, 2014; D’Arcy et al, 2018; Su et al, 2020a) and in-situ dating techniques (Le Béon et al, 2010, 2012; Porat et al, 2010; Duehnforth et al, 2017) are the most promising.…”

“…Among techniques that have been used for such purpose, remote sensing techniques (Frankel and Dolan, 2007; Zhang and Guo, 2013; Regmi et al, 2014; D’Arcy et al, 2018; Su et al, 2020a) and in-situ dating techniques (Le Béon et al, 2010, 2012; Porat et al, 2010; Duehnforth et al, 2017) are the most promising. Previous studies have shown that the extent of alluvial fans can be mapped by morphological parameters (e.g., surface texture, surface relief, and gravel size) (Frankel and Dolan, 2007; Regmi et al, 2014; Brooke et al, 2018; D'Arcy et al, 2018; Purinton and Bookhagen, 2020; Walk et al, 2022). In particular, surface roughness is a universal time-dependent geomorphic feature within arid environments that decreases when there are no perturbations (e.g., hydrological events) that renew the alluvial fan surface (Frankel and Dolan, 2007; Regmi et al, 2014).…”

“…Such datasets can capture fine features of alluvial surfaces at the meters to centimeters scale (Frankel and Dolan, 2007; Haas et al, 2014; Mushkin et al, 2014; Regmi et al, 2014), but the cost to obtain high-resolution data is high, especially over large areas (i.e., tens of kilometers) (Schwendel and Milan, 2020). (b) Spectral characterization from multispectral satellite images is also a powerful index to map alluvial fans in hyperarid regions based on surface mineralogy (Meer et al, 2014; D'Arcy et al, 2018; Walk et al, 2022). However, it requires either the calibration of ground measurements or high-resolution satellite images with a spatial resolution of meters (Walk et al, 2022).…”

“…(b) Spectral characterization from multispectral satellite images is also a powerful index to map alluvial fans in hyperarid regions based on surface mineralogy (Meer et al, 2014; D'Arcy et al, 2018; Walk et al, 2022). However, it requires either the calibration of ground measurements or high-resolution satellite images with a spatial resolution of meters (Walk et al, 2022). (c) Surface reflectance from the field-based spectrometer and hyperspectral remote sensing data can also be used to quantify surface roughness (Farr and Chadwick, 1996; Crouvi et al, 2006; Ferrier and Pope, 2012), but it is impossible to explain the specific absorption features of the spectra in detail and does not apply to map alluvial fans over hundreds kilometers.…”

“…The application of in-situ radiometric dating technologies ( 14 C, optically stimulated luminescence (OSL), and cosmogenic radionuclide (CRN) exposure dating) to determine the ages of alluvial fans are effective methods (Le Béon et al, 2010; Porat et al, 2010; Hajdas et al, 2021). Few samples from morphostratigraphic units might determine the exposure ages, but it does not consider the complexity of alluvial fan aggradation (Duehnforth et al, 2017; Walk et al, 2022). Mapping alluvial fans by surface features can help to select suitable sample positions for in-situ radiometric dating.…”