Discovered in the late 1980s, inactive ice wedges in Yitulihe in the north part of Da Hinggan Mountains, Northeastern China are the southernmost in the Northern Hemisphere, and they are important paleo-environmental i...Discovered in the late 1980s, inactive ice wedges in Yitulihe in the north part of Da Hinggan Mountains, Northeastern China are the southernmost in the Northern Hemisphere, and they are important paleo-environmental indicators. Recently, research was carried out to analyze the hydrogen and oxygen isotopes of an inactive ice wedge from them. The plot of stable isotopes reveals three periods of temperature fluctuations centered approximately at 2.8, 2.3 and 1.9 ka BP. And the resultant temperature was probably lowered by about 2.1, 1.1, and 1.3℃, respectively, in comparison with present temperatures. In conjunction with previous studies, pollen record and radiocarbon dating, the ice wedges probably developed between 3.3 to 1.6 ka BP, and the southern limit of the permafrost （SLP） at that time advanced southwards by around 2°N, i.e., about 200 km.展开更多
基金supported by National Natural Science Foundation of China (Grant No. 40901044)Chinese Academy of Sciences (CAS) 100-Talent Program (Grant No. 2004407)+1 种基金Scholarships for Young Scientists of the State Key Laboratory of Frozen Soils Engineering (Grant No. SKLFSE-ZQ-04)Talent Fund of the Cold and Arid Regions Environmental and Engineering Research Institute, CAS (Grant No. O984971001)
文摘Discovered in the late 1980s, inactive ice wedges in Yitulihe in the north part of Da Hinggan Mountains, Northeastern China are the southernmost in the Northern Hemisphere, and they are important paleo-environmental indicators. Recently, research was carried out to analyze the hydrogen and oxygen isotopes of an inactive ice wedge from them. The plot of stable isotopes reveals three periods of temperature fluctuations centered approximately at 2.8, 2.3 and 1.9 ka BP. And the resultant temperature was probably lowered by about 2.1, 1.1, and 1.3℃, respectively, in comparison with present temperatures. In conjunction with previous studies, pollen record and radiocarbon dating, the ice wedges probably developed between 3.3 to 1.6 ka BP, and the southern limit of the permafrost （SLP） at that time advanced southwards by around 2°N, i.e., about 200 km.
