Cryogenic wedges on the NE Qinghai-Tibet and Ordos Plateaus:Their characteristics,origin and OSL dating

作     者：Stuart A.Harris Stuart A.Harris

作者机构：Department of GeographyUniversity of CalgaryCalgaryAlbertaT2N 1N4Canada 

出 版 物：《Research in Cold and Arid Regions》 (寒旱区科学（英文版）)

年 卷 期：2021年第13卷第6期

页      面：463-473页

核心收录：

学科分类：0709[理学-地质学] 081803[工学-地质工程] 07[理学] 08[工学] 0818[工学-地质资源与地质工程] 0705[理学-地理学] 

主　　题：cryogenic wedges OSL dating NE Qinghai-Tibet Plateau differentiation of primary and secondary wedges baydjarakhs in arid climates 

摘      要：Cryogenic wedges developed due to very cold,rather arid conditions during the maximum of the last cold event when the drying up of the neighboring China Sea resulted in the failure of the East Asian *** the climate ameliorated and the Monsoon rains reappeared,ice-wedges *** warming permitted thawing of the ice infillings accompanied by replacement of the ice by sediments partly from the host ground as well as from the surface by wind or sheet *** cases of extreme surface water flow on slopes after 10 ka B.P.,small baydjarakhs typically c.50 cm high developed,only to have the resulting hollows infilled by sediments carried by wind and/or sheet *** shallow structures form a network on top of many of the cryogenic *** complex history makes dating the ages of the wedges difficult using OSL ***,past field work ignored the problem of the angle of the cut face to the direction of the wedge infilling when sampling the contents of the narrow wedges,resulting in potential contamination of the samples with the host *** of the larger deposits should be alright,but the likelihood of contamination makes the interpretation of the resulting OSL dates from the narrow wedges *** wedges consisting of primary mineral infillings should still have similar OSL dates with depth for a given wedge,but the distinction between ice-wedge infillings and soil wedges is difficult since both can exhibit older dates of the infillings with *** available data suggests that ice-wedges were significantly more common than sediment-filled primary wedges.A protocol to avoid having to obtain large numbers of OSL dates by more careful field sampling and the use of grain size determinations is provided in the Appendix.