Formation and development of polygonal soils in the hyper-arid Atacama Desert and their relevance as a habitat on earth and beyond

• Main Author: Sager, Christof
• Other Authors: Schulze-Makuch, Dirk, Technische Universität Berlin, Hecht, Lutz
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2023
• Subjects: 500 Naturwissenschaften und Mathematik::550 Geowissenschaften; Geologie::558 Geowissenschaften Südamerikas; 500 Naturwissenschaften und Mathematik::570 Biowissenschaften; Biologie::579 Mikroorganismen; Pilze; Algen; Atacama Desert; patterned ground; polygonal soil; habitability; Atacama-Wüste; Habitabilität; polygonale Böden; Ice; permafrost; wedge*
• Online Access: https://depositonce.tu-berlin.de/handle/11303/19045; https://doi.org/10.14279/depositonce-17841

Patterned ground is the overarching term used for natural recurring geometrical shapes that occur on the surfaces of Earth and extraterrestrial planetary bodies in various climatic and geological settings. Polygonal ground is one of the most widespread geomorphological features in the patterned ground domain. It is formed by various mechanisms, including desiccation, thermal contraction, sublimation, freeze-thaw cycles, and tectonic or volcanic processes. These processes result in visible patterns due to particle sorting of differently sized sediments (i.e., sorted patterned ground) or by the formation of cracks due to ground contraction. The cracks can be filled with ice and/or sediment, forming sand or ice wedges (i.e., non-sorted patterned ground). On Earth, most polygonal grounds occur in permafrost environments. Research over the past century has revealed a formation associated with frost-related processes such as frost heave and freeze-thaw cycles and established their use as an environmental proxy holding valuable information on the pedological and climatological conditions under which they develop. However, non-sorted polygonal ground also occurs in the warm and hyper-arid Atacama Desert in Chile, which in contrast to periglacial polygons, have received minor attention, also due to their remote location and associated extreme conditions hampering their early exploration. As a result, the formation of polygons in the Atacama Desert and the environmental information they can provide are little understood. However, such insights are of great relevance for understanding the landscape evolution in the Atacama Desert and hyper-arid environments in general. Nevertheless, their formation differs from their periglacial counterparts, as frost-related processes can be excluded due to the lack of water and enduring subzero temperatures. Instead, desiccation and thermal contraction are thought to be the more relevant formation mechanisms. The Yungay region of the Atacama Desert hosts numerous polygonal networks that ...