摘要
基于冰楔假型和原生沙楔证据，青藏高原东北部倒数第二次冰期的气温比现在低12℃以上，末次冰期最盛期低11℃以上．高原上冰期的降温幅度明显大于同纬度的其他地区，因此青藏高原对气候变化的放大作用在其本身也有表现．青藏高原冰期降温幅度增大的原因可能主要在于冰期中冰川与荒漠面积增加导致的地面反射率增高．
The purpose of the Plan about Global Evolution Study is to obtain and explain the information of climatical variations during geologic periods and human historicl periods so as to provide the basic data for establishing climatic models and forecasting the climatic change in the future. Estimation on the range of climatical variations during the past climatical periods is one of the important aspects in the study.Qinghai-Xizang Plateau as an unique physiographical unit with the largest area, highest elevation and newest age of formation, the data of its climatical variations have the importance in the establishment and examinatin of the models of global climatical variations. Study of lowering amplitude of temperature in glaciation in the plateau is helpful to discussion of effects of the Qinghai-Xizang Platcau on global climatic changes. Ice-wedge casts and fossil sand wedges are indicators of paleoclimatic changes. Field investigation shows that there are ice-wedge casts of penultimate glaciation and ice-wedge casts and fossil sand wedges of Last Glacial Maximum(LGM) in the Northeastern Qinghai-Xizang Plateau. Ice-wedge casts of penultimate glaciation are mainly distributed in Qinghai Lake, Gonghe and Xinghai Basin, of which TL date is 140ka BP. Ice-wedge casts of LGM are found in Zoige Basin and the southern foot of Bayanhar Mountains, and their 14C age is 8.5ka BP. Fossil sand wedges of LGM are mainly distributcd in the source of thc Yellow River and Gonghe Basin, which formed between 30ka BP and l4ka BP. According to environmental significance of ice wedge and sand wedge suggested by Romanovskij, the temperature in the northeastern Qinghai-Xizang Plateau in penulhmate glaciation and Last Glacial Maximum was respectively at least 12℃ and 11℃ lower than that in present, if tectonic uplift is not calculated. Lowering value of temperature in glaciation in the Qinghai-Xizang Plateau was bigger, compared with that of other regions at the same latitude. The reason of big lowering value of temperature in glaciation in the plateau perhaps is increase of albedo resulting from expansion of glacier and desert in glaciation.
出处
《干旱区地理》
CSCD
北大核心
1997年第2期17-24,共8页
Arid Land Geography
基金
国家自然科学基金!49471012
关键词
青藏高原
更新世
降温幅度
古气候
drop range of temperature, Last Glaciation, penultimate glaciation, the Northeastern Qinghai-Xizang Plateau
