【作者】 李霏；

【导师】 马玉贞；

【作者基本信息】 兰州大学 ， 第四纪地质学， 2007， 硕士

【摘要】 本文利用孢粉、粒度和有机碳等环境气候代用指标，通过对孢粉主成分、孢粉重量浓度、孢粉百分含量、中值粒径和总有机碳含量等数据的分析，重建了祖厉河中上游19.9-5.0KaBP期间的植被和气候变化。19.9-15.4 KaBP(末次冰期晚期)研究区气候寒冷。早期植被植被，特别是上游山地发育了以云杉林为主的针叶林，气候相对冷湿。晚期上游山地云杉林可能退缩甚至消失，松林逐渐扩大，较干旱的地区草原出现，气候相对冷干。其间仍有两个气候明显较湿润的时期。约15.4-11.0 kaBP(末次冰消期)研究区植被覆盖度有所增加，气候波动剧烈。上游山地植被以松林为主，局部出现了一些稀疏的阔叶树，草原面积扩大。存在可与Bφlling和Allerφd事件和Old Dryas和Younger Dryas事件对应的两个暖期和两个冷期。11.0-5.0 kaBP(早中全新世)研究区气候暖湿，波动频繁而剧烈。植被以松林为主，阔叶林明显扩张，灌木和草本非常发育。植被整体上展现出以针阔混交林为主的森林草原的景观。从趋势上看，7.2 kaBP后气候开始趋向冷干。研究区在19.9-5.0 KaBP期间大体经历了冷湿-冷干-暖干-暖湿等一系列气候变化过程。其气候变化趋势和气候变化事件与全球气候变化的记录有较好的可比性，特别是末次冰期晚期．末次冰消期一早中全新世以来硝沟剖面所揭示的气候变化的趋势与格陵兰冰芯和古里雅冰芯的记录基本上是一致的，说明其气候变化受控于全球气候要素的变化。气候植被演化特征同时也反映出19.9-5.0 KaBP期间影响研究区的气候系统很可能非常复杂，折射出亚洲季风系统和西风系统复杂的相互作用。研究区在19.9-5.0 KaBP期间的气候演化机制值得进一步研究。更多还原

【Abstract】 This paper discussed the reconstruction of the history of the vegetation and climate changes in the middle- upriver Zuli River during 19.9-5.0 KaBP period, according to the environmental and climatic indexes of pollen, granularity and organic carbon etc., based on the analysis of pollen absolute concentration, pollen percentage concentration and principal components analysis (PCA) of pollen, and Median diameter Grain(Md) analysis and Total Organic Carbon (TOC) analysis and the following conclusions were drawn:During the period of 19.9-15.4 KaBP (Last Glacial Later Period), the climate was cold. During the forepart of this period, especially in the upriver mountains, spruce (Picea) conifer forests were well developed and the climate was relatively cold and humid; during the later period, spruce (Picea) forest in the upriver mountains might degrade or even disappear while Pine forest extended gradually, in the arid area appeared steppe vegetation under a relatively cold and dry climate. Between these two periods appeared two relatively distinct humid climate stages. Around 15.4-11.0 KaBP (Last Deglacial ), the coverage of the vegetation were in better condition and the climate fluctuated tempestuously. In the upper mountains vegetation was dominated by Pine forest with open broad leaves forest appeared partly and the area of the steppe enlarged. At the same time there existed two warm and humid climate periods and two dry and cold climate periods corresponding with B0lling and Aller0d Events and Old Dryas and Younger Dryas Events. Druing 11.05-5.0 KaBP (Early-Mid Holocene) the climate was warm and humid and fluctuated frequently and tempestuously. The vegetation mainly dominated by Pine forest, broadleaves forest had an obvious extension; shrubs and herbs were well developed. It appeared as forest steppe vegetation which was dominated by coniferous-broad leaved mixed forests. After 7.2 KaBP climate tended to be cold and dry according to the trends.In study area, during the 19.9-5.0 KaBP period, climate showed a series of change: cold humid-cold dry-warm dry-warm humid. The trends of the climatic changes and the climate events had good coherence with records of global climate changes, especially the trend of climate changes suggested by XiaoGou profile during Last Glacial Later Period-Last Interglacial-Holocene period was mostly the same as the one showed by records of Greenland Ice Core and Guliya Ice Core. This indicated that the climate changes in study area are controlled by global climate factors. The characters of the climate and vegetation alternation reflected that during 19.9-5.0 Ka BP period the factors that influenced the climate system might be very complicated which indicated the complicated interactions between the Asian monsoon system and westerly currents. The further study on the climatic mechanical alternation is required in this area.更多还原