Preprints
https://doi.org/10.5194/egusphere-2024-592
https://doi.org/10.5194/egusphere-2024-592
15 Apr 2024
 | 15 Apr 2024
Status: this preprint is open for discussion.

Haloturbation in the northern Atacama Desert revealed by a hidden subsurface network of calcium sulphate wedges

Aline Zinelabedin, Joel Mohren, Maria Wierzbicka-Wieczorek, Tibor Janos Dunai, Stefan Heinze, and Benedikt Ritter

Abstract. While the formation of periglacial wedges and polygonal patterned grounds has been extensively studied and many of the processes involved have been understood, knowledge on the formation of similar post-sedimentary features found in arid to hyperarid environments remains largely rudimentary. Our contribution to fill this gap is the investigation of a network of vertically laminated calcium sulphate-rich wedges in the subsurface of the Aroma fan in the northern Atacama Desert. The subsurface wedges are characterised by high anhydrite contents and hence differ from the wedge and polygon structures of other study sites in the Atacama Desert, which appear to have been predominantly formed by thermal contraction or desiccation processes. By contrast, haloturbation mechanisms are thought to be a main driver of wedge formation at the Aroma fan site. Haloturbation requires moisture input, and hence Aroma fan wedge formation is likely to be associated with meteoric water received from sporadic rain events and episodes of arid climate characterised by slightly wetter conditions than prevailing at present. The polygonal patterned ground is covered by a stratigraphically younger gypsum-dominated surface crust cover. The presence of the surface crust could indicate an environmental change towards drier conditions, which favoured surface accumulation of calcium sulphate and other salts by means of atmospheric deposition. Such a climatic shift could have caused a deceleration of haloturbation and other wedge formation processes in the subsurface, although modern sediment conveyance from the surface towards its interior still appears to occur along cracks within the crust. In order to gain comprehensive insights into the complex mechanisms involved in wedge formation and formation rates, the establishment of a geochronological framework directly obtained from wedge and crust material remains indispensable. The temporal resolution of wedge growth stored within the succession of vertical laminae promises a high potential for the calcium sulphate wedges to be used as palaeoclimate archives, potentially helping to unravel wedge and polygonal patterned ground formation in other water-limited environments, such as Mars.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Aline Zinelabedin, Joel Mohren, Maria Wierzbicka-Wieczorek, Tibor Janos Dunai, Stefan Heinze, and Benedikt Ritter

Status: open (until 07 Jun 2024)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-592', Rui-Lin Cheng, 19 May 2024 reply
Aline Zinelabedin, Joel Mohren, Maria Wierzbicka-Wieczorek, Tibor Janos Dunai, Stefan Heinze, and Benedikt Ritter
Aline Zinelabedin, Joel Mohren, Maria Wierzbicka-Wieczorek, Tibor Janos Dunai, Stefan Heinze, and Benedikt Ritter

Viewed

Total article views: 192 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
153 30 9 192 19 8 9
  • HTML: 153
  • PDF: 30
  • XML: 9
  • Total: 192
  • Supplement: 19
  • BibTeX: 8
  • EndNote: 9
Views and downloads (calculated since 15 Apr 2024)
Cumulative views and downloads (calculated since 15 Apr 2024)

Viewed (geographical distribution)

Total article views: 188 (including HTML, PDF, and XML) Thereof 188 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 19 May 2024
Download
Short summary
In order to interpret the formation processes of subsurface salt wedges and polygonal patterned grounds from the northern Atacama Desert, we present a multi-methodological approach. Due to the high salt content of the wedges, we suggest that their formation is dominated by subsurface salt dynamics requiring moisture. We assume that the climatic conditions during the wedge growth were slightly wetter than today, offering the potential to use the wedges as palaeoclimate archives.