Very Large Cryoturbation Structures of Last Permafrost Maximum Age at the Foot of the Qilian Mountains (NE Tibet Plateau, China)

• Published in: Permafrost and Periglacial Processes
• Main Authors: J. Vandenberghe, X. Wang, D. Vandenberghe
• Format: Article in Journal/Newspaper
• Language: unknown
• Subjects: Ice; permafrost
• Online Access: https://doi.org/10.1002/ppp.1847

Unusually large cryoturbation structures (4–4.5 m amplitude), developed in channel gravels and overbank fine‐grained deposits of a river terrace on the NE Tibet Plateau, China, were formed by loadcasting as late Pleistocene‐age permafrost degraded. It is suggested that the oversaturation and liquefaction of the thawed sediments could have been achieved only if the amount of ice in the upper 4–4.5 m of terrace sediments had been very high. The structures, dated at around 26–20 ka by OSL, point to the presence of a massive icy layer existing within a permafrost body during the Last Permafrost Maximum. Copyright © 2015 John Wiley & Sons, Ltd.