【摘要】 <正>近几年来,随着对青藏公路沿线冻土科研工作的深入开展,在楚玛尔河高平原清水河地区发现了较完整的晚更新世──全新世湖相、湖滨相地层。作者在野外调查的基础上对上述地层系统采样进行了C¹⁴年代测定、孢粉分析、土的矿物成分、含盐量、水和冰的化学成分分析及X光衍射测定。本文基于前人的工作并根据上述分析资料及地层的沉积特征试图恢复清水河地区晚更新世以来古气候的变化,并着重探讨其多年冻土的演化过程。更多还原

【Abstract】 According to the investigations of stratigraphic lithology and sedimentary characteristics, radiocarbon C14 dating, pollen analysis of samples, minerial components of soils, chemical components of water and ice, and X ray diffraction determination, the authors reconstructed the palaeoclimate changes in the Qingshui River region since Late Pleistocene,and analyzed the processes of its permafrost evolution.In the primary stage during the Late Pleistocene, the periglacial climate was dominant in this region; in the middle stage the climate became warmer with semiarid steppe environment, i. e. the interglaciation period; and in the last stage the climate turned gradually into more severe cold and aridity. During the last stage,permafrost formed and grew thicker and thicker. Under periglacial climatic background, the climate experinced some fluctuation since Holocene, and it may be divided into five stages as follows: Transitional period ( 10,000-8,000 y. B.P.), warm period (8,000-3,000 y. B. P.), cold period (3,000-2,000 y. B. P.), warm turning period(2,000-500 y.B. P.), and litte ice age ( 500 y. B. P.-end of the 19th century). Through all the stages, the distribution and thickness of permafrost changed correspondingly.更多还原