【作者】 王孝理；

【导师】 周尚哲；

【作者基本信息】 兰州大学 ， 第四纪地质学， 2006， 博士

【摘要】 青藏高原东南部地理位置独特,深受南亚季风的影响,发育了我国最大规模的海洋性冰川（温冰川）,末次冰期盛冰期更留下了规模宏大的冰碛地貌,其中波密境内波堆藏布谷地的冰川地貌形态最为典型,侧碛、终碛的沉积特征非常显著,具有完整的冰碛序列。我们选取波堆藏布主谷内的冰川堆积地貌作为研究对象,运用多种测年技术（ESR、CRN、OSL和14C等）对具有代表性的冰碛序列和冰水阶地进行定年,重建青藏高原东南部地区第四纪冰川演化历史。利用GIS和RS等技术对现代冰川与气候因子之间的关系进行了深入研究,对第四纪冰川波动与气候变化之间的关系进行了初步探讨。 对波堆藏布谷地中的冰碛进行了系统的采集CRN测年样品,特别是白玉沟口附近的典型终碛和达卡桥西侧的冰碛。通过CRN测年技术所得到的冰碛形成的年龄,检测到了两次规模较大的冰川前进,一次是较老的古乡冰期,年龄为113±12.6 ka BP和97.4±10.8 ka BP,对应于深海氧同位素（MIS）6阶段;另一次是以白玉沟口数道高大冰碛垄为代表的冰期,从外到内（即从老到新）冰碛序列的年代为9-11ka BP,12-15.5 ka BP,分别对应于晚冰期的新仙女木事件（YD）和Heirichl事件（也可能是LGM持续到16 KaBP所致）。 对谷地中白玉沟内及其附近的冰水阶地中的显著的二层古土壤采集了6个¹⁴C样品,获得下层古土壤的2个年龄分别为7190±120a BP,5230±120 a BP:上层古土壤的年龄分别为3755±125 a BP,2670±130 a BP,3450±70 a BP和3335±85 a BP。这些年龄数据揭示了藏东南地区在中全新世早期（7.2—5.5ka）和晚期（3.3-3.8 ka）发育了红色古土壤,代表了温暖湿润的气候,与河北平原河流湖泊所反映的气候相一致。 本文以1:10地形图和1987年、1999年陆地卫星图像及区域范围内9个气象站气象观测资料为基础数据,进行了详细的地形分析比较和数据空间结构的探索。基于GIS空间分析和遥感目视解译定量分析,我们选取了3条典型的冰川,分别计算其地形参数（包括长度、面积,高度及梯度等）,重建白玉冰期时三条冰川的规模,详细剖析了朱西沟和白玉沟的冰川发育特点,并分析其形态差异、ELA差异的原因,认为地形因素是影响冰川形态的重要因素。更多还原

【Abstract】 The last glacial maximum presents the dramatically drop in temperature throughout the world, which enlarges the areas of the ice sheets in two poles, extends the alpine glaciers and reduces the equilibrium line altitude of glaciers. But the dropping of the equilibrium line altitude in different areas is not consistent, and there are two reasons for it. On the one hand, the dropping extents in temperature are different;on the other, the equilibrium line altitude is the result of temperature and precipitation, and the influence of topography in the glacial developing area. After the last glacial maximum, the global temperature increases, resulting in the retreats of alpine glaciers, which shaped inimitable glacial landscapes. These various and majestic landforms are of natural landscape, and in different areas and positions, the glacial landforms are different. The study on the style, scale and area of moraines, which are formed by glacial erosion and accumulation in the last glacial maximum, is important for studying the quality, process and erosive accumulation of glaciers in the last glacial maximum. According to the relationship between variations of modern glaciers and climatic conditions, the climatic conditions in the last glacial maximum were reconstructed, in order to understand the effect of temperature, precipitation and topography on glaciers, and the influence of the south Asia monsoon on glaciers, especially on variations of the equilibrium line altitude, to infer the regional climatic change in the future, its contributions to the global climatic change, and the effect of global climatic change on regional climatic change.The southeast Nyanqingtanggula Mountains in the Tibetan plateau develop modern glaciers in large scale, and the last glacial maximum remains large-scale moraines, typically that in the valley of Boduizangbo in Bomi, and that in modern glaciers in the drainage area. Lateral and terminal moraines are very prominent sediments, and they can be used to completely reconstruct the scale, size, length and thickness of the typical glaciers in the valley during the last glacial maximum.The 11 samples of ESR were collected in the Baiyugou valley and in theneighboring fluvioglacial terrace, the age of the sample BYG -1(ESR) at the first moraine is ll.l±1.6ka BP;the age of sample XM -1 at the hummocky moraine is 12.3±1.8ka BP. So the hummocky moraine represented by the sample suggested it may be formed in Boiling event or Allerod warming period in the lateglacial.The 614Csamples were collected in the 2-layer palaeo-soils in the fluvioglacial sediment of Baiyugou valley and neighboring Buduizangbu valley. The two sample ages in the lower layer were 7190±120a BP and 5230±120a BP;the 4 sample ages in the upper layer were 3755±125aBP, 2670±130aBP, 3450±70 a BPand 3335±85 a BP. The sample ages suggest southeast Tibetan Plateau had developed palaeo-soil during the early mid-Holocene(7.2 - 5.5ka) and during the late mid-Holocene, representing warm and moist climate, which is mutually consistent with the climate of the Hebei plain.Late Quaternary glacier fluctuations in the Boduizangbu valley were reconstructed using relative and absolute dating techniques. Our results indicate that younger moraine complexes were left by YD event (cal 11 ka BP) and Lateglacial (ca 13 cal. ka BP) ice advances. Older Late Quaternary glacier advances occurred during Marine Oxygen Isotope Stages (MIS) 6. No relics of Middle or Early Pleistocene glaciations could be found. During MIS6, glaciers advanced down to an altitude of at least 2600m a.s.l., corresponding to an ELA depression of approximately 1300 m. At about 2700m a.s.l., the YD glacier reached almost the thickness of the former MIS2 glacier and retreated some time before 16 cal. ka BP. The Lateglacial glacier advanced again several times to altitudes between 2700 and 2800m a.s.l.Based on the map of 1:100,000, the satellite images in 1987 and 1999, and the meteorologic data gathered from 34 weather stations in research areas, a detailed topography analysis and comparison was made to explore the data’s spatial feature. According to the spatial analysis of GIS and the quantitative analysis of the remote sensing, three typical glaciers were chosen, in order to respectively calculate the terrain parameters, including length, area, height and gradient and so on. The characteristics of the vertical sections and cross-sections of Zhuxigou and Baiyugou were discussed in detail, and the feature was analyzed. At the end, the effect of thebedrock and its topography on the glaciers was discussed.ELA was calculated through the weighted average and three different methods. The height of ELA of Baiyu ice age can be got, respectively 4004m asl, 3827m asl and 3882m asl, and each of them descend down 602 m, 380m and 372m, compared with that of modern times. By analyzing the statistics of temperature and precipitation in the nine weather stations around the research area, a distributed model of temperature and precipitation based on DEM was established, and the results show the gradient of summer average temperature in the southeast Tibet is lower than the vertical gradient of annual average temperature. According to the relationship between ELA and temperature (summer temperature) & precipitation (solid precipitation), the variation of climatic factors (temperature and precipitation) in the research area in the last glacial maximum were discussed.更多还原