Polygonal cracks in bedrock on Earth and Mars: Implications for weathering

Chan, Marjorie A.; Yonkee, W. Adolph; Netoff, Dennis I.; Seiler, Winston M.; Ford, R. L.

doi:10.1016/j.icarus.2007.09.026

Cited by 52 publications

(49 citation statements)

References 35 publications

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“…(For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.) meters (El Maarry et al, 2010, 2012Harris, 2004;Neal et al, 1968;Weinberger, 1999), teepee structures from chemical precipitates (Dixon, 2009;Shaw and Thomas, 1989), or patterned ground from thermal cycling or ice-related processes (Chan et al, 2008;Korteniemi and Kreslavsky, 2012;Levy et al, 2009;Mangold et al, 2004;Mellon, 1997). There are no obvious vertical structures in the sediment beneath the scalloped layer edges, however, so that direct evidence for any of these mechanisms is lacking.…”

Section: Interpretation Of Fine-textured Depositsmentioning

confidence: 99%

Sedimentology and climatic environment of alluvial fans in the martian Saheki crater and a comparison with terrestrial fans in the Atacama Desert

Morgan

Howard

Hobley

et al. 2014

Icarus

110

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a b s t r a c tThe deflated surfaces of the alluvial fans in Saheki crater reveal the most detailed record of fan stratigraphy and evolution found, to date, on Mars. During deposition of at least the uppermost 100 m of fan deposits, discharges from the source basin consisted of channelized flows transporting sediment (which we infer to be primarily sand-and gravel-sized) as bedload coupled with extensive overbank mud-rich flows depositing planar beds of sand-sized or finer sediment. Flow events are inferred to have been of modest magnitude (probably less than $60 m 3 /s), of short duration, and probably occupied only a few distributaries during any individual flow event. Occasional channel avulsions resulted in the distribution of sediment across the entire fan. A comparison with fine-grained alluvial fans in Chile's Atacama Desert provides insights into the processes responsible for constructing the Saheki crater fans: sediment is deposited by channelized flows (transporting sand through boulder-sized material) and overbank mudflows (sand size and finer) and wind erosion leaves channels expressed in inverted topographic relief. The most likely source of water was snowmelt released after annual or epochal accumulation of snow in the headwater source basin on the interior crater rim during the Hesperian to Amazonian periods. We infer the Saheki fans to have been constructed by many hundreds of separate flow events, and accumulation of the necessary snow and release of meltwater may have required favorable orbital configurations or transient global warming.

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Section: Interpretation Of Fine-textured Depositsmentioning

confidence: 99%

Sedimentology and climatic environment of alluvial fans in the martian Saheki crater and a comparison with terrestrial fans in the Atacama Desert

Morgan

Howard

Hobley

et al. 2014

Icarus

110

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“…The complex patterns and processes associated with the advancement of this interface, as well as the morphology of landforms and landscapes, are likely to be affected both by the heterogeneities in the unweathered bedrocks and by the weathering process itself. While some authors favor major controls by preexisting structures [Twidale, 2002;Vidal Romani, 2008], others emphasize pattern-forming instabilities arising during the weathering processes [Strudley et al, 2006;Chan et al, 2008].…”

Section: Introductionmentioning

confidence: 99%

Porosity evolution and crystallization-driven fragmentation during weathering of andesite

et al. 2011

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[1] A 10 m thick andesitic sill intrusion from the Neuquén Basin, Argentina, shows spectacular examples of spheroidal weathering and Liesegang banding. The Liesegang patterns demonstrate how andesite blocks, initially cut out by a preweathering joint set, are subdivided by fractures formed during the spheroidal weathering process. The stresses that cause fracturing originate from the growth of ferrihydrite and calcite in the pore space of the andesite, partly at the expense of original ilmenite, amphibole, and plagioclase. The porosity evolution and fracture formation during progressive weathering was characterized by scanning electron microscopy studies, X-ray computed tomography, and He-and Hg-porosimetry. Fresh andesite has a porosity of approximately 8%, and a major fraction (>80%) of the pore volume is composed of pores less than 10 mm in diameter. The extent of pore filling during weathering increases with pore size. Pores more than 100 mm are almost completely filled by an intimate intergrowth of calcite and ferrihydrite, whereas pores less than 10 mm are filled less than 50%. The fracturing associated with spheroidal weathering is caused by mineral growth in the largest pores, which account for 10%-20% of the total porosity. The periodic precipitation of the weathering product to form Liesegang bands indicates a significant supersaturation threshold before nucleation commences. The increase in the weathering product growth rate with increasing size is therefore most likely due to higher nucleation probabilities in larger pores.Citation: Jamtveit, B., M. Kobchenko, H. Austrheim, A. Malthe-Sørenssen, A. Røyne, and H. Svensen (2011), Porosity evolution and crystallization-driven fragmentation during weathering of andesite,

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“…Polygonal fractures are variously attributed to weathering, desiccation, thermal stresses, or diagenesis of clays (Johnston, 1927;Netoff, 1971;Howard and Selby, 2009;Riley et al, 2012;Goehring, 2013). Chan et al (2008) interpreted the polygonal fracture patterns at Checkerboard Mesa, Utah, as products of tensile weathering stresses caused by temperature and moisture fluctuations and suggested that they may be good analogs for interpreting similar-appearing polygons in the Utopia Planitia region of Mars.…”

Section: Polygonal Patternsmentioning

confidence: 99%

“…However, the Utopia Planitia features are much larger than those formed by these mechanisms on Earth (McGill, 1986;Hiesinger and Head, 2000). Chan et al (2008) suggested that the polygons in the Navajo Sandstone (which they interpreted as weathering features) were in fact the most appropriate analogs for the Utopia Planitia structures. We suggest that although thermal processes may have aided the propagation of pre-existing fractures (Anderson, 1998;Martel, 2017), the polygonal patterns in the Navajo Sandstone are primarily the result of sheeting-joint development.…”

Section: Implications For Planetary Geologymentioning

confidence: 99%

Sheeting joints and polygonal patterns in the Navajo Sandstone, southern Utah: Controlled by rock fabric, tectonic joints, buckling, and gullying

Loope

Burberry

2018

Geosphere

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Sheeting joints are ubiquitous in outcrops of the Navajo Sandstone on the west-central Colorado Plateau, USA. As in granitic terrains, these are opening-mode fractures and form parallel to land surfaces. In our study areas in south-central Utah, liquefaction during Jurassic seismic events destroyed stratification in large volumes of eolian sediment, and first-order sheeting joints are now preferentially forming in these structureless (isotropic) sandstones. Vertical cross-joints abut the land-surface-parallel sheeting joints, segmenting broad (tens of meters) rock sheets into equant, polygonal slabs ~5 m wide and 0.25 m thick. On steeper slopes, exposed polygonal slabs have domed surfaces; eroded slabs reveal an onion-like internal structure formed by 5-m-wide, second-order sheeting joints that terminate against the crossjoints, and may themselves be broken into polygons. In many structureless sandstone bodies, however, the lateral extent of first-order sheeting joints is severely limited by pre-existing, vertical tectonic joints. In this scenario, non-conjoined sheeting joints form extensive agglomerations of laterally contiguous, polygonal domes 3-6 m wide, exposing exhumed sheeting joints. These laterally confined sheeting joints are, in turn, segmented by short vertical cross-joints into numerous small (~0.5 m) polygonal rock masses. We hypothesize that the sheeting joints in the Navajo Sandstone form via contemporaneous, land-surface-parallel compressive stresses, and that vertical cross-joints that delineate polygonal masses (both large and small) form during compression-driven buckling of thin, convex-up rock slabs. Abrasion of friable sandstone during runoff events widens vertical tectonic joints into gullies, enhancing land-surface convexity. Polygonal rock slabs described here provide a potential model for interpretation of similar-appearing patterns developed on the surface of Mars.

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Polygonal cracks in bedrock on Earth and Mars: Implications for weathering

Cited by 52 publications

References 35 publications

Sedimentology and climatic environment of alluvial fans in the martian Saheki crater and a comparison with terrestrial fans in the Atacama Desert

Sedimentology and climatic environment of alluvial fans in the martian Saheki crater and a comparison with terrestrial fans in the Atacama Desert

Porosity evolution and crystallization-driven fragmentation during weathering of andesite

Sheeting joints and polygonal patterns in the Navajo Sandstone, southern Utah: Controlled by rock fabric, tectonic joints, buckling, and gullying

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