Thermally induced movements in ice-wedge polygons, western arctic coast: a long-term study

Mackay, J. Ross

doi:10.7202/004846ar

Cited by 162 publications

(259 citation statements)

References 61 publications

(27 reference statements)

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“…The anti-syngenetic sand wedges are similar in size and morphology to anti-syngenetic ice wedges reported by Mackay (1990Mackay ( , 1995Mackay ( , 2000 in the region. The sand wedges differ, however, from the anti-syngenetic ice wedges in that they formed beneath a flat rather than hilly landscape.…”

Section: Thermal-contraction Cracking and Sand-wedge Growthsupporting

confidence: 50%

Syngenetic sand veins and anti‐syngenetic sand wedges, Tuktoyaktuk Coastlands, western Arctic Canada

Murton

Bateman

2007

Permafrost & Periglacial

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Sand‐sheet deposits of full‐glacial age in the Tuktoyaktuk Coastlands, western Arctic Canada, contain syngenetic sand veins 1–21 cm wide and sometimes exceeding 9 m in height. Their tall and narrow, chimney‐like morphology differs from that of known syngenetic ice wedges and indicates an unusually close balance between the rate of sand‐sheet aggradation and the frequency of thermal‐contraction cracking. The sand sheets also contain rejuvenated (syngenetic) sand wedges that have grown upward from an erosion surface. By contrast, sand sheets of postglacial age contain few or sometimes no intraformational sand veins and wedges, suggesting that the climatic conditions were unfavourable for thermal‐contraction cracking. Beneath a postglacial sand sheet near Johnson Bay, sand wedges with unusually wide tops (≤3.9 m) extend down from a prominent erosion surface. The wedges grew vertically downward during deflation of the ground surface, and represent anti‐syngenetic wedges. The distribution of sand veins and wedges within the sand sheets indicates that the existence of continuous permafrost during sand‐sheet aggradation can be inferred confidently only during full‐glacial conditions. Copyright © 2007 John Wiley & Sons, Ltd.

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Section: Thermal-contraction Cracking and Sand-wedge Growthsupporting

confidence: 50%

Syngenetic sand veins and anti‐syngenetic sand wedges, Tuktoyaktuk Coastlands, western Arctic Canada

Murton

Bateman

2007

Permafrost & Periglacial

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“…Aspect and slopeangle conditions play a minor role in the statistics of our polygon dataset. This is unexpected, as subsurface and micro-climate conditions also change with slope angle and aspect and should have an influence on initial thermal contraction cracking and subsequent polygon formation (e.g., Lachenbruch, 1966;Mackay, 2000;Mackay and Burn, 2002). Furthermore, interrelationships of slope conditions and polygon shape or dimension could be observed, as was discussed above.…”

Section: Relationship Between Geomorphometry and Genesis For The Terrmentioning

confidence: 80%

“…This is supported by the relationship between larger trough widths and steeper slope angle. The evolutionary change from low-centered to high-centered polygons caused by ice-wedge degradation (e.g., Washburn, 1979;Mackay, 2000) might be reinforced on slopes by increasing drainage along the polygon-outlining troughs (Fortier et al, 2007). This degradation factor dominates the recent development of the high-centered polygons in the middle and upper Adventdalen and prevents active frost cracking (Table 5); this is also true because snow accumulating in the deep troughs would have an insulating effect, preventing crack initiation (e.g., Mackay, 1974Mackay, , 1992.…”

Section: Relationship Between Geomorphometry and Genesis For The Terrmentioning

confidence: 99%

Polygon pattern geomorphometry on Svalbard (Norway) and western Utopia Planitia (Mars) using high-resolution stereo remote-sensing data

et al. 2011

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Polygonal systems formed by thermal contraction cracking are complex landscape features widespread in terrestrial periglacial regions. The manner in which cracking occurs is controlled by various environmental factors and determines dimension, shape, and orientation of polygons. Analogous small-scale features are ubiquitous in Martian mid-and high-latitudes, and they are also inferred to originate from thermal contraction cracking. We studied the geomorphometry of polygonally-patterned ground on Svalbard to draw a terrestrial analogy to small-scale polygonal structures in scalloped terrain in Martian mid-latitudes. We performed a comparative quantitative terrain analysis based on high-resolution stereo remote-sensing data (HRSC-AX and HiRISE) in combination with terrestrial field data and multivariate statistics to determine the relationship of polygon geomorphometry to local environmental conditions. Results show that polygonal structures on Svalbard and in Utopia Planitia on Mars are similar with respect to their size and shape. A comparable thermal contraction cracking genesis is likely. Polygon evolution, however, is strongly related to regional and local landscape dynamics. Individual polygon dimensions and orthogonality vary according to age, thermal contraction cracking activity, and local subsurface conditions. Based on these findings, the effects of specific past and current environmental conditions on polygon formation on Mars must be considered. On both Earth and Mars, the smallest polygons represent young, recently-active low-centered polygons that formed in fine-grained ice-rich material. Small, low-centered Martian polygons show the closest analogy to terrestrial low-centered ice-wedge polygons. The formation of composite wedges could have occurred as a result of local geomorphological conditions during past Martian orbital configurations. Larger polygons reflect past climate conditions on both Earth and Mars. The present degradation of these polygons depends on relief and topographical situation. On Svalbard the thawing of ice wedges degrades high-centered polygons; in contrast, the present appearance of polygons in Utopia Planitia is primarily the result of contemporary dry degradation processes.

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“…Wet and dry phases can then be explained by a feedback between sediment accumulation, controlled by the input of organic and mineral material, and the upward growth of ice-wedges, which is limited by the rate of sediment accumulation (Harry & Gozdzik 1988;Mackay 2000). Wet phases may correspond to periods when the amplitude between a polygon's ridges and centre is relatively large (higher values for Q g , Q s and P) although upward growth of icewedges, and the continued development of ridges, will gradually slow or cease, to be resumed only when sufficient sediments have accumulated in the polygon centre.…”

Section: Figmentioning

confidence: 99%

Long‐term sensitivity of a High Arctic wetland to Holocene climate change

Ellis

Rochefort

2005

Journal of Ecology

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Summary 1The response of peat-rich permafrost soils to human-induced climate change may be especially important in modifying the global C-flux. We examined the Holocene developmental record of a High Arctic peat-forming wetland to investigate its sensitivity to past climate change and aid understanding of the likely effects of future climate warming on high-latitude ecosystems. 2 The microhabitat of mosses was quantified in the present-day polygon-complex at Bylot Island (73 ° N, 80 ° W) and used to interpret the radiocarbon-dated macrofossil record of three cores, comprising c. 3500 years of wetland development. Recurrent wet and dry phases in the reconstructed palaeohydrological record indicated pronounced temporal variability. Wet and dry phases were compared between cores and with palaeoclimatic proxy values, measured as percentage melt and δ 18 O in nearby ice cores. 3 Periodic wet and dry phases appear unrelated to past climate over c. 50% of the combined stratigraphic records, and are attributable instead to geomorphological mechanisms. At other times, association of wet and dry phases with significantly lower and higher values of percentage melt and δ 18 O indicate a possible effect of past climate change on polygon hydrology and vegetation, although inconsistencies between cores suggest that local geomorphological processes continued to modify a regional climatic effect. However, during a period incorporating the Little Ice Age ( c. 305-530 cal. years  ), reconstructed moisture and vegetation change is pronounced and consistent among all three cores. 4 The results provide strong evidence for the sensitivity of a High Arctic terrestrial ecosystem to past climate change during the Holocene. The estimated magnitude of changes in soil moisture between wet and dry phases is sufficient to imply recurrent shifts in wetland function, periodically impacted upon by pronounced climatic variability, although controlled principally by autogenic processes. The structure and function of such wetlands may therefore be susceptible to predicted, human-induced climate warming.

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Thermally induced movements in ice-wedge polygons, western arctic coast: a long-term study

Cited by 162 publications

References 61 publications

Syngenetic sand veins and anti‐syngenetic sand wedges, Tuktoyaktuk Coastlands, western Arctic Canada

Syngenetic sand veins and anti‐syngenetic sand wedges, Tuktoyaktuk Coastlands, western Arctic Canada

Polygon pattern geomorphometry on Svalbard (Norway) and western Utopia Planitia (Mars) using high-resolution stereo remote-sensing data

Long‐term sensitivity of a High Arctic wetland to Holocene climate change

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