EGI OpenIR
新疆博斯腾湖沉积物粒度特征及其记录的沉积环境变化
Alternative TitleThe Research on Grain Size Characteristics and Sedimentary Environment Change of Bosten Lake in Xinjiang
华攸胜
Subtype硕士
Thesis Advisor吉力力·阿不都外力
2019-06-30
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline理学硕士
Keyword博斯腾湖 沉积物粒度 环境演变 Bosten Lake Sediment Grain Size Environmental Evolution
Abstract湖泊作为地球水圈的重要组成部分,是地球生物生存的重要场所也是人类生产发展的重要资源,湖泊沉积物在湖泊形成、发展过程中包含了丰富物质信息、环境信息以及人类活动等重要信息,沉积物粒度作为湖泊沉积物重要组成部分,其颗粒大小受到物源、搬运介质、沉积动力等因素影响,是研究区域环境变化的重要环境指标。本研究以博斯腾湖沉积物粒度作为研究对象,利用 Kriging 插值法分析了博斯腾湖表层沉积物粒度变化特征,分析了表层粒度参数变化, 并探讨了表层沉积物粒度反映的沉积环境变化;通过 210Pb 测年建立了博斯腾湖岩芯沉积年代序列,据此分析了沉积物粒度时间变化特征, 并用粒径-标准偏差法提取了岩芯沉积物粒度对环境较为敏感的粒级组分, 与器测数据进行比较, 由此揭示敏感粒级组分所反映的研究区环境演化历史, 为区域环境演化以及中亚环境演变历史的研究提供理论依据。 主要结论如下:(1)博斯腾湖表层沉积物粒度及参数特征: 位于河口附近的沉积物粒度以粗颗粒为主,位于开阔湖区的沉积物粒度以细颗粒为主。 表层沉积物粒度以黏土质和细粉砂质为主,占了总体的 61.92%,砂质组分含量最低。 平均粒径范围为 7.35~28.12 μm,平均值为 13.03μm,分选系数数值高值区出现在西岸湖区和南岸湖区中部左右,低值区集中在东岸湖区和西南岸,总体由西北向西南、向东降低。偏态由湖中心对称向东西两岸的负偏态变化,并且负偏态增强,湖泊西岸负偏态最强, 峰态以尖峰态为主。(2) 博斯腾湖表层沉积物粒度所反映的沉积动力与沉积环境: 沉积物主要受控于河流流水作用、湖水动力和湖泊水深的影响。位于河口附近的沉积物粒度在河流的搬运作用下,巨大的势能将河流沿岸碎屑物搬运入湖,附近湖水较浅,水动力较强,湖床较为平坦,较粗颗粒沉积在河口附近。 湖区西南岸湿地分布着大量的芦苇,对湖泊水动力起到削弱作用,因此沉积物以细颗粒为主。湖区南岸等深线较为密集,湖床较陡,粗颗粒不易沉积下来,因此黏土质含量较多。湖区东岸远离河口,沉积动力较弱,细粉砂质含量较为丰富。 平均粒径变化特征反映了湖区的西岸和西北岸沉积动力最强,总体上沉积动力由西向东、由西北向西南逐渐减小。(3)博斯腾湖岩芯沉积物粒度特征: 沉积物粒度以细粉砂质(4~16 μm)为主; 中粉砂质(16~32 μm) 在 1~25 cm 沉积物粒度较为稳定, 但在 26~41cm 出现了极大的波动性; 沉积物中值粒径受控于粗粉砂质(32~64 μm) 含量的变化。(4) 博斯腾湖岩芯沉积物粒度反映的沉积环境变化及其揭示的环境意义:通过 210Pb 测年得到博斯腾湖沉积物岩芯底部(41cm)沉积年代为 1868 AD,平均沉积速率为 0.21 g/(cm2·a)。 通过粒径-标准偏差法提取的敏感组分 C2(粒径范围 7.59~22.91 μm)与气测数据具有一定的相关性,由此揭示了博斯腾湖过去 150年的湖泊水位变化历史。其中 1910~1930 年低水位时期反映了区域性干旱事件。因此, 湖泊水位作为湖泊沉积粒度变化的低频影响因子,可以通过湖泊沉积物中环境敏感组分的含量重建过去博斯腾湖水位的波动历史,为研究湖泊的历史变化规律及其影响因素提供一种新的途径。
Other AbstractAs an important part of the earth's hydrosphere, lakes are important places for thesurvival of the earth's organisms and important resources for human production anddevelopment. Lake sediments contain abundant material information, environmentalinformation and human activities during the formation and development of lakes. As animportant part of Lake sediments, sediment grain size is affected by provenance andtransportation. The factors such as quality and sedimentary dynamics are importantenvironmental indicators for studying regional environmental changes.In this study, the grain size of Bosten Lake sediments was taken as the researchobject, and the characteristics of grain size change of surface sediments were analyzedby Kriging interpolation method, the variation of grain size parameters of surfacesediments was analyzed, and the changes of sedimentary environment reflected by grainsize of surface sediments were discussed. The sedimentary chronological sequence ofcore of Bosten Lake was established by 210Pb dating, and the characteristics of grainsize time change were analyzed accordingly. Characterization and particle size-standarddeviation method were used to extract the environmentally sensitive grain size fractionsof core sediments, and the results were compared with the measured data, thus revealingthe environmental evolution history of the study area reflected by the sensitive grainsize fractions, providing a theoretical basis for the study of regional environmentalevolution and the environmental evolution history of Central Asia. The mainconclusions are as follows:(1) Grain size and parameter characteristics of the surface sediment in Bosten Lake:the grain size of the sediment near the estuary is mainly coarse, and that of the sedimentin the open lake area is mainly fine. The grain size of surface sediment is mainly clayeyand fine silty, accounting for 61.92% of the total, and the content of sand component isthe lowest. The average particle size ranges from 7.35 μm to 28.12 μm, and the averagevalue is 13.03 μm. the high value area of sorting coefficient appears in the west bank lake area and the middle of the south bank lake area, while the low value area isconcentrated in the east bank lake area and the west south bank, which is generallyreduced from northwest to southwest and East. The negative skewness changes fromthe center symmetry of the lake to the East and West banks, and the negative skewnessincreases. The negative skewness is the strongest on the West Bank of the lake, and thepeak state is mainly peak state.(2) The sedimentary dynamics and environment reflected by the grain size of thesurface sediment in Bosten Lake: the sediment is mainly controlled by the influence ofriver flow, Lake hydrodynamic force and lake water depth. Under the action of rivertransportation, the sediment particle size near the estuary transports the debris along theriver into the lake with great potential energy. The nearby lake water is shallow, thehydrodynamic force is strong, the lake bed is relatively flat, and the coarser particlesare deposited near the estuary. There are a large number of reed distributed in thewetland on the southwest Bank of the lake area, which weakens the hydrodynamic forceof the lake, so the sediment is mainly composed of fine particles. In the South Bank ofthe lake area, the isobath is relatively dense, the lake bed is relatively steep, and coarseparticles are not easy to deposit, so the clay content is more. The East Bank of the lakearea is far away from the estuary, with weak sedimentary power and rich fine siltycontent. The characteristics of the average grain size change reflect that the sedimentarypower of the West and northwest Bank of the lake area is the strongest, and thesedimentary power decreases gradually from west to East and from northwest tosouthwest.(3) Grain size characteristics of Bosten Lake core sediment: the grain size ofsediment is mainly fine silty (4-16 μm); the grain size of medium silty (16-32 μm) isrelatively stable at 1-25 cm, but has great fluctuation at 26-41 cm; the median grain sizeof sediment is controlled by the content change of coarse silty (32-64 μm).(4) The change of sedimentary environment reflected by the grain size of BostenLake sediment core and its environmental significance: the sedimentary age of the bottom of Bosten Lake sediment core (41cm) is 1868 AD by 210Pb dating, and theaverage sedimentary rate is 0.21 g / (cm2 · a). The sensitive component C2 (particle sizerange 7.59-22.91 μm) extracted by the particle size standard deviation method has acertain correlation with the gas measurement data, thus revealing the lake water levelchange history of Bosten Lake in the past 150 years. Among them, the low water levelperiod from 1910 to 1930 reflected regional drought events. Therefore, lake water level,as a low-frequency influence factor of lake sediment grain size change, can reconstructthe fluctuation history of past Bosten Lake water level through the content ofenvironmental sensitive components in lake sediment, and provide a new way to studythe historical change rule and its influence factors of lake.
Subject Area自然地理学
Language中文
Document Type学位论文
Identifierhttp://ir.xjlas.org/handle/365004/15328
Collection中国科学院新疆生态与地理研究所
研究系统
Affiliation中国科学院新疆生态与地理研究所
First Author Affilication中国科学院新疆生态与地理研究所
Recommended Citation
GB/T 7714
华攸胜. 新疆博斯腾湖沉积物粒度特征及其记录的沉积环境变化[D]. 北京. 中国科学院大学,2019.
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