河北白洋淀地区晚更新世以来环境演变研究

发布时间：2018-04-22 00:32

本文选题：白洋淀地区 + 晚更新世　；参考：《中国地质大学(北京)》2015年硕士论文

【摘要】：河北白洋淀地区晚更新世以来处于东亚季风区,是古环境演变的敏感区。第四纪沉积物分布广泛、连续,沉积厚度大,是古气候环境变化的良好记录。区域古气候研究多集中在岩性和孢粉分析,而本文利用粒度和磁化率进行精细分析。本文主要研究了白洋淀周边三个有代表性剖面,通过分析岩性、磁化率和粒度特征,结合光释光和14C测年结果,揭示河北白洋淀地区的环境演变规律。主要结论如下:1.通过光释光和14C年代数据确定了剖面时代,同时经过14C年代校正、结合沉积环境的变化分析了年代的合理性和可靠性。通过拟合计算得到底部年龄为121.843ka BP,属于晚更新以来地层。2.在测年数据的基础上,结合岩性分析,建立了末次间冰期以来三个阶段的地层层序。下层从121ka BP至75ka BP,沉积相为河流相,沉积物以中粗砂和极细砂为主;中层从75ka BP至10ka BP,沉积相以河流相和滨湖相为主,沉积物粒径较为分散,以粘土、粉砂为主,含有少量极细砂;上层从10ka BP至现代:沉积物以粘土、粉砂细粒物质为主,湖沼相与河流相交替,发育黑色、灰褐色泥碳层,较多层位发现底栖生物类化石。3.根据磁化率和粒度的阶段特征和环境指示意义分析,发现晚更新世早期,气候温暖湿润;晚更新世晚期气候较干冷,该阶段内气候又经历了冷-暖-冷的阶段性波动;全新世向暖湿转变,中期温暖湿润,该区域生物生长状况较好且湖泊经历扩张与收缩的演进过程。该区域晚更新世以来的气候环境演变对应深海氧同位素MIS5a,MIS4,MIS3,MIS2,MIS1。
[Abstract]:Since the late Pleistocene the Baiyangdian area in Hebei Province is located in the East Asian monsoon region and is a sensitive area for paleoenvironmental evolution. Quaternary sediments are widely distributed, continuous and thick, which is a good record of paleoclimate environment change. The study of regional paleoclimate is mainly focused on lithology and sporopollen analysis, but the fine analysis is based on particle size and magnetic susceptibility. In this paper, three representative sections around Baiyangdian are studied. By analyzing lithology, magnetic susceptibility and granularity characteristics, combined with the results of photoluminescence and 14C dating, the environmental evolution law of Baiyangdian area in Hebei Province is revealed. The main conclusions are as follows: 1. The age of section is determined by the data of photoluminescence and 14C, and the rationality and reliability of the age are analyzed by the correction of 14C and the change of sedimentary environment. By fitting calculation, the bottom age is 121.843ka BP, which belongs to stratum. 2. 2. On the basis of dating data and lithologic analysis, the stratigraphic sequence of three stages since the last interglacial period was established. From 121ka BP to 75ka BP, the sedimentary facies are fluvial facies, medium coarse sand and very fine sand, while from 75ka BP to 10ka BP, the sedimentary facies are mainly fluvial facies and lakeside facies, and the grain size of sediment is dispersed, mainly of clay and silt. It contains a small amount of very fine sand, the upper layer from 10ka BP to the modern: the sediment is mainly clay, silt fine grained material, the lake and marsh facies alternate with the river facies, develop black, grayish brown muddy carbon layer, the benthos fossils. 3 are found in many layers. According to the phase characteristics of magnetic susceptibility and granularity and the analysis of environmental indicators, it is found that in the early late Pleistocene, the climate was warm and humid, and in the late late Pleistocene the climate was dry and cold, during which the climate experienced a period of cold, warm and cold fluctuations. With the transition from Holocene to warm and wet and warm and humid in the middle of the period, the living conditions of the region are relatively good and the lakes have experienced the process of expansion and contraction. The evolution of the climate environment since the late Pleistocene in the region corresponds to the deep-sea oxygen isotope MIS5a4 (MIS3) MIS2 (MIS1).
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P532

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