Thermal‐contraction‐crack networks as evidence for late‐Pleistocene permafrost in Inner Mongolia, China
Abstract Numerous wedges on the Ordos Plateau show typical characteristics of periglacial sand wedges that enable them to be distinguished from desiccation cracks in clayey illuviation soil horizons. The sand wedges are organized in two generations of polygonal networks. The older generation is a la...
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crwiley:10.1002/ppp.476 2024-09-15T18:11:35+00:00 Thermal‐contraction‐crack networks as evidence for late‐Pleistocene permafrost in Inner Mongolia, China Vandenberghe, J. Zhijiu, Cui Liang, Zhao Wei, Zhang 2004 http://dx.doi.org/10.1002/ppp.476 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fppp.476 https://onlinelibrary.wiley.com/doi/pdf/10.1002/ppp.476 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Permafrost and Periglacial Processes volume 15, issue 1, page 21-29 ISSN 1045-6740 1099-1530 journal-article 2004 crwiley https://doi.org/10.1002/ppp.476 2024-07-09T04:13:19Z Abstract Numerous wedges on the Ordos Plateau show typical characteristics of periglacial sand wedges that enable them to be distinguished from desiccation cracks in clayey illuviation soil horizons. The sand wedges are organized in two generations of polygonal networks. The older generation is a large‐scale network with a diameter of 8 to 9 m and wedge depths up to more than 2 m. The younger generation has a mean diameter of 3 to 4 m and is formed within the large networks. It consists of shallow (0.6 to 1 m deep) but relatively wide wedges. In contrast to the typical sand wedges that form within continuous permafrost, the shallow wedges formed probably as ‘ground wedges’ by seasonal freezing. Ice wedges and cryoturbations developed only rarely, and exclusively in the most humid areas. Thermal‐contraction cracking occurred mainly between 26 and 20 ka BP, indicating mean annual temperatures at least 13°C lower than present. Before and after that period mean annual temperatures were at least 7 to 8.5° lower than today. The presence of these periglacial phenomena show that the southern limit of continuous permafrost in Inner Mongolia occurred south of 38°N during the Last Glacial Maximum. Copyright © 2004 John Wiley & Sons, Ltd. Article in Journal/Newspaper Ice permafrost Permafrost and Periglacial Processes wedge* Wiley Online Library Permafrost and Periglacial Processes 15 1 21 29 |
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English |
description |
Abstract Numerous wedges on the Ordos Plateau show typical characteristics of periglacial sand wedges that enable them to be distinguished from desiccation cracks in clayey illuviation soil horizons. The sand wedges are organized in two generations of polygonal networks. The older generation is a large‐scale network with a diameter of 8 to 9 m and wedge depths up to more than 2 m. The younger generation has a mean diameter of 3 to 4 m and is formed within the large networks. It consists of shallow (0.6 to 1 m deep) but relatively wide wedges. In contrast to the typical sand wedges that form within continuous permafrost, the shallow wedges formed probably as ‘ground wedges’ by seasonal freezing. Ice wedges and cryoturbations developed only rarely, and exclusively in the most humid areas. Thermal‐contraction cracking occurred mainly between 26 and 20 ka BP, indicating mean annual temperatures at least 13°C lower than present. Before and after that period mean annual temperatures were at least 7 to 8.5° lower than today. The presence of these periglacial phenomena show that the southern limit of continuous permafrost in Inner Mongolia occurred south of 38°N during the Last Glacial Maximum. Copyright © 2004 John Wiley & Sons, Ltd. |
format |
Article in Journal/Newspaper |
author |
Vandenberghe, J. Zhijiu, Cui Liang, Zhao Wei, Zhang |
spellingShingle |
Vandenberghe, J. Zhijiu, Cui Liang, Zhao Wei, Zhang Thermal‐contraction‐crack networks as evidence for late‐Pleistocene permafrost in Inner Mongolia, China |
author_facet |
Vandenberghe, J. Zhijiu, Cui Liang, Zhao Wei, Zhang |
author_sort |
Vandenberghe, J. |
title |
Thermal‐contraction‐crack networks as evidence for late‐Pleistocene permafrost in Inner Mongolia, China |
title_short |
Thermal‐contraction‐crack networks as evidence for late‐Pleistocene permafrost in Inner Mongolia, China |
title_full |
Thermal‐contraction‐crack networks as evidence for late‐Pleistocene permafrost in Inner Mongolia, China |
title_fullStr |
Thermal‐contraction‐crack networks as evidence for late‐Pleistocene permafrost in Inner Mongolia, China |
title_full_unstemmed |
Thermal‐contraction‐crack networks as evidence for late‐Pleistocene permafrost in Inner Mongolia, China |
title_sort |
thermal‐contraction‐crack networks as evidence for late‐pleistocene permafrost in inner mongolia, china |
publisher |
Wiley |
publishDate |
2004 |
url |
http://dx.doi.org/10.1002/ppp.476 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fppp.476 https://onlinelibrary.wiley.com/doi/pdf/10.1002/ppp.476 |
genre |
Ice permafrost Permafrost and Periglacial Processes wedge* |
genre_facet |
Ice permafrost Permafrost and Periglacial Processes wedge* |
op_source |
Permafrost and Periglacial Processes volume 15, issue 1, page 21-29 ISSN 1045-6740 1099-1530 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/ppp.476 |
container_title |
Permafrost and Periglacial Processes |
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15 |
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1 |
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21 |
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29 |
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1810449170657443840 |