新疆艾比湖晚全新世沉积环境演变及气候变化机制浅析

发布时间：2018-07-07 21:50

本文选题：艾比湖 + 粒度　；参考：《华东师范大学》2017年硕士论文

【摘要】：湖泊的发育演化的过程就深受区域气候和环境的影响,其沉积特征在研究全球变化和区域响应方面具有不可替代的优势。艾比湖位于西北内陆干旱区,可以很好的记录西风控制的西北干旱-半干旱地区的气候变化过程。本文通过对艾比湖南岸沉积剖面粒度和地球化学元素等气候代用指标的分析,在AmS14C测年的基础上,重建了湖区2030BP以来的气候环境演化过程,并通过区域气候记录的对比分析,初步得出以下结论和认识:1)剖面风成沉积物粒度频率分布模式多为单峰分布,砂质组分含量最高。湖相沉积粒度频率多为双峰分布,砂质组分的含量波动较大。沉积剖面环境敏感组分的含量与剖面平均粒径的变化特征较为一致,含量的剧烈波动反映湖区的风沙活动比较频繁。CIA值在剖面中的变化范围为39.17～50.48,属于初级风化阶段。2)根据沉积物粒度和元素地球化学剖面变化特征,重建艾比湖2030 BP以来的环境演化过程:83.8～79.3cm(约2030～1980BP),沉积区气候较冷干,风沙活动增强。79.3～75.4cm(约1980～1930BP),沉积环境变得湿润,降水增多,化学风化作用增强。75.4～71.5cm(约1930～1880BP)湖区气候较冷干。72.5cm处(约1890 BP)敏感组分含量达到最大值,风沙活动增强。71.5～66.0cm(约1880～1800BP),沉积环境变得湿润,风沙活动减弱。66.0～59.5cm(约1800～1720BP)艾比湖气候快速干旱,风沙活动急剧增加。59.5～50cm(约1718～1600 BP)风沙活动微弱,沉积环境变得湿润。50～0cm(约1600BP至今)为风成沉积阶段,风沙活动显著。3)艾比湖南岸沉积记录与青藏高原的冰芯、树轮以及天山的石笋记录存在良好的可比性,与西风强度和太阳辐射关系密切,二者可能是导致区域中短尺度气候变化的驱动因素。
[Abstract]:The process of lake development and evolution is deeply influenced by regional climate and environment, and its sedimentary characteristics have irreplaceable advantages in studying global change and regional response. Ebinur Lake is located in the arid region of the Northwest China. It can well record the process of climate change in the arid and semi-arid region controlled by the west wind. Based on the analysis of the grain size of sedimentary profile and geochemical elements in the south bank of Ebinur Lake, based on the AmS14C dating, the evolution process of climate environment since 2030BP in the lake area was reconstructed, and the regional climate records were compared and analyzed. The following conclusions and understandings are obtained: the granularity frequency distribution model of aeolian sediments in section 1 is mostly single-peak distribution, and the content of sandy components is the highest. The frequency of lacustrine sedimentary granularity is mostly bimodal distribution, and the content of sandy components fluctuates greatly. The content of the environmental sensitive components in the sedimentary profile is consistent with the variation of the average particle size of the profile. The violent fluctuation of the content indicates that the relatively frequent wind-sand activity in the lake area, the CIA value varies from 39.17 to 50.48 in the profile, which belongs to the primary weathering stage (.2) according to the variation characteristics of sediment granularity and geochemical profile of elements. Since the reconstruction of Ebinur Lake 2030 BP, the environmental evolution process is: 83.8 ~ 79.3 cm (2030 ~ 1980BP), the climate of sedimentary area is relatively cold and dry, the activity of wind and sand is increased by .79.3 ~ 75.4 cm (about 1980 ~ 1930 BP), and the sedimentary environment becomes humid and precipitation increases. Chemical weathering enhanced 71.5 cm (about 1930 ~ 1880 BP). The climate of the lake area reached the maximum at 72.5 cm (about 1890 BP) compared with the cold and dry area, and the aeolian sand activity increased .71.5 ~ 66.0cm (about 1880,1800BP), and the sedimentary environment became humid. The aeolian sand activity decreased by 59.5 cm (about 1800 ~ 1720BP), and the aeolian sand activity increased sharply by .59.5 ~ (50) cm (about 1718181600 BP), and the sedimentary environment became moist. 500 cm (about 1600BP) was the aeolian sedimentary stage. (3) the sedimentary records on the south bank of Ebinur Lake are comparable with the records of ice cores, tree rings and stalagmites in the Qinghai-Tibet Plateau, and are closely related to the intensity of westerly winds and solar radiation. Both may be the drivers of regional short-and medium-scale climate change.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P532;P512.2

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