巴丹吉林沙漠湖岸钙华沉积机制研究
发布时间：2018-12-11 01:38
【摘要】：巴丹吉林沙漠许多湖泊分布钙华,关于钙华成因及其气候环境意义,尚无定论:针对沙漠湖泊钙华基础特征调查及其成因的研究也不多见。钙华作为水化学作用的产物,研究其沉积机制能为其他相关科研工作提供新的证据,如湖泊演化、气候演化、地下水补给来源等。本论文依托"巴丹吉林沙漠及其周边地区1:25万水文地质调查"项目(编号:DD20160295),针对沙漠内钙华分布规模较大的7个湖泊进行湖水、地下水取样分析,并以车日格勒湖为重点,钻取了湖岸3.8米深的钙华岩芯,通过SEM扫描、能谱分析、岩矿测试、铀系测年等方法,确定了钙华沉积时期及其地球化学特征。为研究钙华沉积机制,开展了室内模拟实验,重点研究沉积过程中温度效应、混合效应的影响,同时借助PHREEQC软件,建立正向与反向模型,研究沉积过程中pH值、PCO_2、温度、混合比例等因素的影响,最终阐明车日格勒钙华沉积的物质来源及其成因机制。论文主要取得以下成果与认识:1:总结了钙华分布与地球化学特征钙华主要分布在湖岸泉水出露带及其附近区域。样品CaO含量多高于50%,结晶形态主要为六方柱状、三角锥状方解石与针状文石,反映了低温的沉积环境。碳氧同位素均值为δ13C=1.31‰,δ180=-3.52‰,两者相关性强,反映了钙华沉积时脱气作用的影响。测年范围在597～4216aBP范围内,乱序的测年结果表明了钙华加积模式包括自下而上与后期充填;距今2000年内钙华沉积速率加快,且现代仍在不断沉积。2:分析了钙华沉积的水动力条件湖区地下水由南东向北西径流,氘氧同位素、动态监测数据显示,车日格勒全年接受四周地下水补给,依靠蒸发排泄,为排泄型湖泊,这种地下水-湖水系统的作用关系为钙华沉积于湖岸泉水出露带提供了持续的动力学条件。3:阐明了钙华沉积的水化学基础钙华湖泊湖水类型为Cl-Na型,Ca~(2+)含量低,CO_3~(2-)+HCO_3~-含量高;湖四周地下水类型以Cl-S04-Na型、Cl-CO_3-Na型为主,CO32-+HCO3-含量低,Ca~(2+)含量较高;多数水样方解石、文石饱和指数大于0,为钙华沉积提供了基本条件。4:揭示了湖岸钙华沉积机制沉积机制包括地下水与湖水的混合效应、泉水脱气效应、蒸发浓缩效应,沉积过程受到温度效应、pH值、二氧化碳分压(PCO_2)等因素的影响。根据碳酸钙沉淀量大小,上述效应对钙华沉积的重要性程度为:混合效应脱气效应蒸发浓缩温度效应,沉淀能力对比为106.22.41。沉积环境中PCO_2降低,水体pH值升高,水动力条件的增大,均有利于钙华形成。沉积时CO_2气体主要来自大气以及土壤中生物的呼吸和分解作用;沉积钙质主要来自于地下水对古湖沉积物与风积砂的溶滤。
[Abstract]:There is no conclusion on the origin of calcareous blooms and their climatic and environmental significance. The investigation on the basic characteristics of calcareous blooms in desert lakes and their causes are rare. As a product of hydrochemistry, the study of the deposition mechanism of Caohua can provide new evidence for other related scientific research work, such as lake evolution, climate evolution, groundwater recharge source and so on. Based on the project of "1: 250 000 Hydrogeology Survey of Badain Jilin Desert and its surrounding areas" (number: DD20160295), this paper carries out lake water sampling and groundwater sampling analysis for 7 lakes with large distribution scale of calcareous water in the desert. With the emphasis on Cheigre Lake, the cavertine core, which is 3.8 meters deep along the shore of the lake, is drilled. By means of SEM scanning, energy spectrum analysis, rock and ore testing, uranium dating and so on, the Calciferous sedimentary period and its geochemical characteristics are determined. In order to study the mechanism of travertine deposition, laboratory simulation experiments were carried out, focusing on the influence of temperature effect and mixing effect during deposition process. At the same time, with the help of PHREEQC software, the forward and reverse models were established to study the pH value and PCO_2, temperature in the deposition process. Finally, the material source and genetic mechanism of Cegler travertine deposition are elucidated by the influence of mixed ratio and other factors. The main achievements of this paper are as follows: 1. The distribution and geochemical characteristics of the calcareous blooms are summarized, which are mainly located in the outburst zone of the spring water along the lake bank and its adjacent areas. The CaO content of the samples is more than 50, and the crystalline morphology is mainly hexagonal, triangular-shaped calcite and acicular dolomite, which reflects the low temperature sedimentary environment. The average values of carbon and oxygen isotopes are 未 13C=1.31 鈥，
本文编号：2371614
[Abstract]:There is no conclusion on the origin of calcareous blooms and their climatic and environmental significance. The investigation on the basic characteristics of calcareous blooms in desert lakes and their causes are rare. As a product of hydrochemistry, the study of the deposition mechanism of Caohua can provide new evidence for other related scientific research work, such as lake evolution, climate evolution, groundwater recharge source and so on. Based on the project of "1: 250 000 Hydrogeology Survey of Badain Jilin Desert and its surrounding areas" (number: DD20160295), this paper carries out lake water sampling and groundwater sampling analysis for 7 lakes with large distribution scale of calcareous water in the desert. With the emphasis on Cheigre Lake, the cavertine core, which is 3.8 meters deep along the shore of the lake, is drilled. By means of SEM scanning, energy spectrum analysis, rock and ore testing, uranium dating and so on, the Calciferous sedimentary period and its geochemical characteristics are determined. In order to study the mechanism of travertine deposition, laboratory simulation experiments were carried out, focusing on the influence of temperature effect and mixing effect during deposition process. At the same time, with the help of PHREEQC software, the forward and reverse models were established to study the pH value and PCO_2, temperature in the deposition process. Finally, the material source and genetic mechanism of Cegler travertine deposition are elucidated by the influence of mixed ratio and other factors. The main achievements of this paper are as follows: 1. The distribution and geochemical characteristics of the calcareous blooms are summarized, which are mainly located in the outburst zone of the spring water along the lake bank and its adjacent areas. The CaO content of the samples is more than 50, and the crystalline morphology is mainly hexagonal, triangular-shaped calcite and acicular dolomite, which reflects the low temperature sedimentary environment. The average values of carbon and oxygen isotopes are 未 13C=1.31 鈥，
本文编号：2371614
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