干旱区生态环境知识资源中心(Arid): New type of sand wedge polygons in the salt cemented soils of the hyper-arid Atacama Desert

Arid

DOI	10.1016/j.geomorph.2020.107481
	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
通讯作者	Sager, C (corresponding author), Tech Univ Berlin, Zentrum Astron & Astrophys, Astrobiol Res Grp, D-10623 Berlin, Germany.
来源期刊	GEOMORPHOLOGY
ISSN	0169-555X
EISSN	1872-695X
出版年	2021
卷号	373
英文摘要	Polygonal grounds are landscape features commonly associated with periglacial environments originating from freeze-thawing cycles or frost-related processes. However, such a genesis is unlikely for polygonal grounds on alluvial surfaces in the warm and hyper-arid Atacama Desert due to the lack of enduring sub-zero temperatures and limited water availability, whereas a cracking mechanism based on thermal contraction and/or desiccation is more plausible. To differentiate between those mechanisms, we performed a quantitative morphometric terrain characterization in combination with a geochemical and sedimentological analysis on three polygonal networks located in the Yungay area of the Atacama Desert, Chile. Our data show that these sand wedge polygons differ from other polygonal features in the Yungay area such as salt polygons and mud crack polygons from playa environments in regard to composition, morphometry and topographical setting. The investigated polygonal soils are composed of siliciclastic sediment that is mainly cemented by sulfates (gypsum & anhydrite) in the shallow ground (similar to 0-50 cm) and by nitrates and chlorides in the deeper ground (similar to 50-100 cm) while being separated by about 1 m deep, salt-poor and V-shaped sand wedges. The low clay content (similar to 2 wt%) makes an exclusive desiccation origin less relevant whereas the high salt content (63 wt%) and the high surface temperature variations make thermal contraction origin more likely. Morphometric data indicate a link between topography and polygon geometry, as the flat-centered polygons (mean size 3.9 to 4.7 m) are aligned either in slope direction or perpendicular to it, while being more elongated on steeper slopes, which is common to thermal contraction polygons. Although we cannot exclude that desiccation cracking plays a minor role for the formation of the here described polygons, we conclude that their genesis is dominated by thermal contraction. (c) 2020 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
英文关键词	Patterned ground Sand wedge polygon Atacama Desert Hyper-arid
类型	Article
语种	英语
开放获取类型	Green Published, hybrid
收录类别	SCI-E
WOS记录号	WOS:000597330600004
WOS关键词	ATMOSPHERIC DEPOSITION ; MARS ; CRACKING ; NITRATE
WOS类目	Geography, Physical ; Geosciences, Multidisciplinary
WOS研究方向	Physical Geography ; Geology
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/347929
作者单位	[Sager, Christof; Airo, Alessandro; Arens, Felix L.; Schulze-Makuch, Dirk] Tech Univ Berlin, Zentrum Astron & Astrophys, Astrobiol Res Grp, D-10623 Berlin, Germany; [Schulze-Makuch, Dirk] German Res Ctr Geosci GFZ, Sect Geomicrobiol, D-14473 Potsdam, Germany; [Schulze-Makuch, Dirk] Leibniz Inst Freshwater Ecol & Inland Fisheries I, Dept Expt Limnol, D-12587 Stechlin, Germany
推荐引用方式 GB/T 7714	Sager, Christof,Airo, Alessandro,Arens, Felix L.,et al. New type of sand wedge polygons in the salt cemented soils of the hyper-arid Atacama Desert[J],2021,373.
APA	Sager, Christof,Airo, Alessandro,Arens, Felix L.,&Schulze-Makuch, Dirk.(2021).New type of sand wedge polygons in the salt cemented soils of the hyper-arid Atacama Desert.GEOMORPHOLOGY,373.
MLA	Sager, Christof,et al."New type of sand wedge polygons in the salt cemented soils of the hyper-arid Atacama Desert".GEOMORPHOLOGY 373(2021).