中国陆域出露地壳76种元素岩石地球化学图的构建——方法、问题与展望

    Construction of the petrogeochemical map of 76 elements in the exposed crust across the Chinese continent: Methods, challenges, and prospects

    • 摘要: 出露地壳是岩石圈与土壤圈、水圈、大气圈接触的关键界面,出露地壳岩石地球化学图可为不同圈层间元素分布与循环研究提供关键的基础地球化学数据。由于大尺度出露地壳元素地球化学图绘制受到数据量和制图技术的制约,目前尚无一张覆盖中国陆域的出露地壳地球化学图。本文结合已掌握的16 000余条岩石地球化学数据和基础地质资料,创新性地提出制图技术路线:构建岩石地球化学库、地层结构信息库和地质单元空间信息库;从基础数据库提取地层和岩体的地理空间信息;将岩石地球化学信息赋予地层和岩体,获得地层和岩体的空间分布及其元素含量;通过GIS技术实现对出露地壳76种元素含量空间分布模式的可视化表达。此外,本文对制图流程存在的地质信息精确度、特殊岩性岩石样品缺乏、可靠性评价与适用范围等问题进行剖析,并提出解决方案。出露地壳元素地球化学图具有重要的应用价值,可为地球化学背景调查和岩石—沉积物元素循环等研究提供基础数据支撑。

       

      Abstract: The exposed crust is the critical interface where the lithosphere interacts with the pedosphere, hydrosphere, and atmosphere. The petrogeochemical map of the exposed crust can provide essential fundamental geochemical data for investigating the distributions and cycles of elements among different spheres. However, the plotting of the large-scale petrogeochemical map of the exposed crust has been constrained by the limited data volume and mapping technology. Consequently, no such a map covering the Chinese continent is available. This study proposed an innovative mapping technology roadmap based on over 16,000 petrogeochemical data and fundamental geological information. First, the databases for petrogeochemical information, stratigraphic structure information, and spatial information of geological units were constructed. Second, the geospatial information of strata and rock masses was extracted from the basic databases. Third, the petrogeochemical information was assigned to strata and rock masses to obtain their spatial distributions and element contents. Fourth, the spatial distribution patterns of 76 elements in the exposed crust were visualized using geographical information system (GIS) technology. Additionally, this study analyzed the challenges in the mapping process, including geological information accuracy, the lack of samples for special lithologies, reliability assessment, and scope of application, finally proposing corresponding solutions. The petrogeochemical map of the exposed crust demonstrates significant application potential, providing foundational data for investigating geochemical background and rock-sediment element cycling.

       

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