黄土高原西部地区晚更新世以来古气候环境的演变趋势

本文依据黄土高原西部地区大量的C~(14)年代测定和孢粉组合分析资料,研究了这一地区晚更新世以来古气候环境的演变趋势。指出:兰州、靖远南部至环县(含环县)一线以北地区,现代草原和荒漠草原下的半干旱气候环境可能在晚更新世以来已基本形成,目前更偏干些,但兰州黄河以南阶地距今7600年左右仍属半湿润气候环境。兰州、靖远南部至环县一线以南地区,现代森林草原和草原下的半湿润气候环境是在近7400年以来才逐渐形成的、距今7400年前这一地区的相当一部分山地的古气候可能较现代更湿润些。

EVOLUTION TENDENCY OF PLAEOCLIMATIC ENVIRONMENT IN THE WEST LOESS PLATEAU SINCE THE LATE PLEISTOCENE

Based on a great deal of the data from C14 dating measurement and analyses of sporo-pollen combinations, this paper dealt with the evolution tendency of palaeoclimatic environment in the west loess plaleau since the late plaistocene. It was found that in the area north of the line going from Lanzhou through the southern Jingyuan to Huanxian County,the semi-arid climatic environment under the modern steppe and the desert steppe might have been created basically since the late pleistocene and it is drier at present than ever before. However, in the stepped land south of the Yellow River at Lanzhou before about 7600 years back from now, it might be in a semi-humid climatic environment. In the area south of the same line as aboue, the semi-humid climatic environment under the modern forest-grasslands and grasslands might have been gradually created only for the late 7400 years. Before then,the plaeoclimate in most of mountain region of the same area might be more humid than at present.This finding may be considered as a scientific basis for the conservation and development of natural resources in the areas studied.