【作者】 辛蔚；

【导师】 程捷；

【作者基本信息】 中国地质大学(北京) ， 地理学， 2012， 硕士

【摘要】 第四纪的气候演变研究对于预测未来全球气候变化意义重大，特别是季风区边缘等敏感区的古气候演变。本文在腾格里沙漠北缘古湖泊区以浅钻形式获取高分辨率沉积物样品，并配合北部一系列剖面进行气候演变分析，选取粒度、磁化率、孢粉等气候代用指标，最终划分出5个阶段：(1)中更新世末期（145.1-138.9ka B.P.）的干冷阶段：水流条件不稳定，气候偏干冷，后期白刺等灌木类大量生长。(2)晚更新世早期（138.9-125.1ka B.P.）的温暖干旱阶段：湖泊水面缩小，气候偏干。草本植物多，为典型的荒漠草原景观。后期可能出现过一次短时期的干旱加剧事件。(3)晚更新世中后期（125.1-50ka B.P.前后）的温暖偏干阶段：湖泊面积扩大，气候略由干旱向湿转变，仍以偏干旱为主，典型的荒漠草原景观。(4)晚更新世末期（50ka前后-14.2ka B.P.）的凉干阶段：植被丰富程度为整个钻孔范围内最高，流域上游偏凉，大量云杉属花粉随河水注入湖泊，湖泊面积扩大。这个时期对应猪野泽MIS3的高湖面时期。(5)晚更新世末期过渡至全新世及之后（14.2-0ka B.P.）的波动干旱化阶段：气候突变为干冷，后又渐渐回温回湿，随着温度湿度的增加呈现“全新世最宜期”，之后出现突发的干旱事件。后期气候逐渐呈干旱化趋势，温度波动频繁，湖泊渐渐干涸。研究区上述气候演变阶段基本与全球气候背景及前人研究结论吻合，但由于地区差异，各个阶段开始的时间及内部水热组合有着其特殊性，对样品数据的解读也因人而异，该地区的详细气候演变过程仍有待今后进一步的研究。更多还原

【Abstract】 Quaternary’s climate change is very important to the study of the future globalclimate, especially the climate of monsoon’s boundary zone in North China because ofits sensitivity to the climate changes. We get sediment samples with high-resolutionfrom the shallow drilling which is at the north of Tengger Desert, and from the sections.Basis of the analysis on magnetic susceptibility, granularity and pollen records,with OSL age determination test, the climate evolution from the late Pleistocene at thenorth of Tengger Desert can be divided into5stages as follows:1. The late part of Middle Pleistocene (145.1-138.9ka B.P.). Cold and dry,hydrodynamic conditions was not stable, and a large number of shrubs existed.2. Early Late Pleistocene (138.9-125.1ka B.P.). Warm and dry, the lake narrowed,the vegetation was dominated by herbs, classic desert steppe. There might be a shorttime dry event at the late part of this period.3. The late part of Late Pleistocene (125.1-about50ka B.P.). Warm and less dry,the lake expanded, the climate began to turn wet, desert steppe.4. The end of Late Pleistocene (about50ka-14.2ka B.P.). Cool and dry, the lakeexpanded, variety of vegetation types, the cool environment at upstream brought asignificant increase of percentage of Picea pollen. This period matches the high waterlevel period of Zhuye Lake in MIS3.5. To the Holocene till now (14.2-0ka B.P.). Climate fluctuation stage, the climateturned to cold and dry quickly at first, then getting warm and wet. A dry event occurredat this period. The main trend of the climate after the middle Holocene was drying. Thelake began to dry up.The climate evolution of study area is matched with previous studies and the globalclimate background, it also has Particularity in many respects. And because theconclusion depends on the way of sample handling and personal understanding to thedata, there may be some other opinions about the climate evolution.更多还原