New type of sand wedge polygons in the salt cemented soils of the hyper-arid Atacama Desert

Sager, Christof; Airo, Alessandro; Arens, Felix L.; Schulze‐Makuch, Dirk

doi:10.1016/j.geomorph.2020.107481

Cited by 13 publications

(20 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Temperatures as high as that have been recorded in 10 cm depth close to our study site, after a rain experiment when the soil moisture still reached 100%, indicating the presence of liquid water (Sager et al, 2021). Considering that these temperatures can be reached at shallow depth and that rainwater can dampen the soil at 10-30 cm depth for months (Schulze-Makuch et al, 2018;Sager et al, 2021;Jordan et al, 2020), we assume that the formation of anhydrite in the chusca horizon can occur through precipitation out of solarheated water after a rain event with retention time of several months. At depths below 50 cm the temperatures remain too low for this process to occur.…”

Section: Gypsum Vs Anhydritesupporting

confidence: 53%

“…The porous and permeable chusca horizon is most frequently exposed to meteoric water and therefore is the most dynamic horizon, which could explain why measured isotopic fractionation is stronger than seen in the modeled data. This upper soil horizon is also affected by salt efflorescence after rain events and through artificial rain experiments (Sager et al, 2021, Pfeiffer et al, 2021, which indicates more complex water pathways at the surface than dominant downward migration, influencing potentially also the isotopic fractionation. Furthermore, rainwater infiltration is not homogeneous and is most intense along the sand wedges (Owen et al, 2013), presumably affecting the lateral isotope pattern.…”

Section: Water-soil Interactionsmentioning

confidence: 99%

“…The HD and TD soil profiles located on inactive alluvial fan deposits correspond well to the hyperarid soil type described by Ericksen (1981). Due to the gentle slope and porous chusca horizon surface, rainwater usually infiltrates entirely into the subsurface (Pfeiffer et al, 2021;Sager et al, 2021). As a result of minimal erosion, the accumulation of salts results in a net deposition (Ewing et al, 2006).…”

Section: Elevation-related Soil Attributesmentioning

confidence: 99%

See 2 more Smart Citations

Geochemical proxies for water-soil interactions in the hyperarid Atacama Desert, Chile

Arens

Airo

Feige

et al. 2021

CATENA

Self Cite

View full text Add to dashboard Cite

The Atacama Desert is the oldest and driest non-polar desert on Earth. Millions of years of hyperaridity enabled salt accumulations through atmospheric deposition. These salts can serve as proxies to decipher the interaction between water and soil as well as to understand the habitability with changing environmental settings. Therefore, we investigated four soil profiles regarding their mineralogy, salt abundance, and sulfate stable isotopic composition. The profiles were located along an elevation transect in the hyperarid region southeast of Antofagasta, Chile. The two lower sites situated on the distal parts of inactive alluvial fan deposits were subject to occasional fog occurrences. The upper steeper-sloped sites experienced no fog but are subject to minimal erosion. In all soil profiles, sulfates are the dominant salts showing a downward transition from gypsum to anhydrite that is accompanied by an increase of highly soluble salts and a decrease of sulfate δ 34 S and δ 18 O values. These trends are consistent with downward directed water infiltration during rare rain events causing salt dissolution followed by precipitation within the deeper soil column. This conclusion is also w supported by our Rayleigh fractionation model. We attribute the presence of anhydrite at > 40 cm depth to the cooccurrence of nitrate and chloride salts, which decreases water activity during sulfate precipitation and therefore drives anhydrite formation. Along the elevation transect, the total salt inventories of each profile show a trend for nitrates and chlorides concentration decreasing with elevation. This observation together with the sulfate stable isotopes indicates a fog-independent source and suggests remobilization of soluble salts through enhanced washout from hillslopes to alluvial fans. These findings are essential for assessing the longterm regional habitability of hyperarid environments and have also relevance for Mars.

show abstract

Section: Gypsum Vs Anhydritesupporting

confidence: 53%

Section: Water-soil Interactionsmentioning

confidence: 99%

Section: Elevation-related Soil Attributesmentioning

confidence: 99%

See 1 more Smart Citation

Geochemical proxies for water-soil interactions in the hyperarid Atacama Desert, Chile

Arens

Airo

Feige

et al. 2021

CATENA

Self Cite

View full text Add to dashboard Cite

show abstract

“…PNs occurring on these soils in the Atacama Desert (Fig. 1 ) exhibit ~ 1 m deep and salt-poor sand wedges outlining salt-rich polygons of a uniform flat-center morphology 25 . They exhibit an orthogonal to hexagonal pattern geometry, and elongated polygons have either one or two dominant orientations, preferably parallel or perpendicular to the slope.…”

Section: Introductionmentioning

confidence: 97%

“…However, the details on the formation of PNs remain under debate, such as the driving forces behind the crack formation. The proposed processes range from thermal contraction, where cementation by salts results in cohesive soils and makes them susceptible to thermal stress 25 and/or salt dehydration 12 , 14 , both being cyclic processes. The details on the importance of rain events for PN formation remain unclear, although, its involvement is certain as rainwater infiltration, which is insufficient to fully wash out the salts, creates the vertical salt sequence of these indurated soils 12 , 22 .…”

Section: Introductionmentioning

confidence: 99%

Eolian erosion of polygons in the Atacama Desert as a proxy for hyper-arid environments on Earth and beyond

Sager

Airo

Arens

et al. 2022

Sci Rep

Self Cite

View full text Add to dashboard Cite

Polygonal networks occur on various terrestrial and extraterrestrial surfaces holding valuable information on the pedological and climatological conditions under which they develop. However, unlike periglacial polygons that are commonly used as an environmental proxy, the information that polygons in the hyper-arid Atacama Desert can provide is little understood. To promote their use as a proxy, we investigated a polygonal network within an inactive channel that exhibits uncommonly diverse surface morphologies and mineral compositions, using geochemical and remote sensing techniques. Our findings show that the polygons belong to a continuous network of the same genetic origin. Their differences result from post-formational differential eolian erosion up to 50 cm depth, exposing indurated subsurface horizons rich in sulfate or nitrate and chloride. Their location in an ancient channel could lead to the misinterpretation of fluvial polygon erosion, however, we find no such signs but evidence for aqueous resurfacing of microtopography by fog and minimal rainwater infiltration. Our findings extend the use of polygons as proxies in the Atacama Desert, indicating saline soils and hyper-arid conditions. We conclude that this example of polygon erosion can guide future polygon research, especially regarding the use of erosional surfaces on Earth and beyond to gain valuable subsurface insights.

show abstract

Atacama Desert, Natural Analog

Pinti

2022

Encyclopedia of Astrobiology

View full text Add to dashboard Cite

New type of sand wedge polygons in the salt cemented soils of the hyper-arid Atacama Desert

Cited by 13 publications

References 36 publications

Geochemical proxies for water-soil interactions in the hyperarid Atacama Desert, Chile

Geochemical proxies for water-soil interactions in the hyperarid Atacama Desert, Chile

Eolian erosion of polygons in the Atacama Desert as a proxy for hyper-arid environments on Earth and beyond

Atacama Desert, Natural Analog

Contact Info

Product

Resources

About