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    基于土壤元素组成探讨雄安新区沉积地貌特征、物质来源及其与环境的关系

    Discussion on sedimentomorphic characteristics, material sources and their relationship with the environment based on the composition of soil in Xiong’an New Area

    • 摘要:
      研究目的 探讨雄安新区第四纪不同沉积地貌单元内土壤元素含量及其组成分布规律、控制影响因素及其沉积物质来源,为研究区域古地理、表生地球化学环境等方面提供地球化学依据。
      研究方法 本文利用雄安新区土地质量地球化学调查与监测获取的表层土壤元素含量数据,通过元素含量或比值示踪等多元统计方法,揭示了区域元素地球化学分布规律与表生环境的关系。
      研究结果 冲湖积平原亚区土壤具有低SiO2和Na2O,高Al2O3、Fe2O3、MgO、CaO、K2O和Na/Rb特征;冲洪积平原亚区土壤具有高SiO2和Na2O,低Al2O3、Fe2O3和Ca/Ba特征。研究区土壤地球化学常量元素的分布主要受沉积物源源区化学风化程度的控制,同时表生环境对常量元素的贫化富集也存在一定的影响。源区目前处于以斜长石风化为主的中等化学风化程度阶段,风化产物未遭受钾交代影响。区内各沉积地貌单元土壤样品成土母质物源主要来自雄安新区西侧太行山隆起的成熟大陆石英质物源区,同时在冲湖积平原亚区的洼地小区地貌单元内还存在部分少量的样品成土母质来源于基性火山岩物源区和中性岩火成物源区。
      结论 土壤元素含量、元素比值、元素组合(Rb–U–Ga、Fe–Mg–Ni–V均一化累加和)等地球化学指标特征能有效指示区内各沉积地貌环境,对成土母质特性具有示踪作用。

       

      Abstract:
      This paper is the result of environmental geological survey engineering.
      Objective This paper aims to investigate the distribution characteristics, the contents and distribution of soil elements in different sedimentary geomorphic units of Quaternary, the control factors and the sources of sediment materials in Xiong’an New area, and to provide geochemical bases for the study of regional palaeogeographic evolution and epigenetic geochemical environments.
      Methods Based on the surface element content data obtained from the geochemical survey and monitoring of land quality in Xiong’an New Area, this study employs multivariate statistical methods(such as elemental content analysis and ratio tracing) to reveal the relationship between regional elemental geochemical distribution patterns and the epigenetic environment.
      Results The soil in the alluvial−lacustrine plain subregion has the characteristics of low value of SiO2 and Na2O, and high value of Al2O3、Fe2O3、MgO、CaO、K2O and Na/Rb. The soil in the alluvial−diluvial plain subregion is characterized by high SiO2 and Na2O, and low Al2O3、Fe2O3 and Ca/Ba. The distribution of soil geochemical major elements is primarily controlled by chemical weathering intensity of source sediments, while epigenetic environment also influences the depletion and enrichment of major elements. The source area is currently in the stage of moderate chemical weathering dominated by plagioclase weathering, with no evidence of potassium metasomatism in weathering products. The soil parent materials in each sedimentary geomorphic unit are mainly derived from the mature continental quartz source of Taihang uplift on the west side of Xiong’an new district. Additionally, in the subregion of alluvial plain, parent materials of a small proportion of samples are from mafic volcanic and neutral igneous rocks.
      Conclusions Geochemical indicators such as soil element contents, element ratios and element combinations (Rb−U−Ga, Fe−Mg−Ni−V) can effectively differentiate sedimentary geomorphic environments in the study area and serve as reliable tracers for soil parent material properties.

       

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