The geochemical composition of the terrestrial surface (without soils) and comparison with the upper continental crust
The geochemical composition of the terrestrial surface (without soils) and comparison with the upper continental crust
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DOI：
10.1007/s00531-010-0635-x
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发表时间：
2011
影响因子：
2.3
通讯作者：
J. Hartmann;H. Dürr;N. Moosdorf;M. Meybeck;S. Kempe
中科院分区：
文献类型：
--
作者：
J. Hartmann;H. Dürr;N. Moosdorf;M. Meybeck;S. Kempe
陆地表面，即“地球的皮肤”，是地球系统主要储存库（大陆和海洋地壳、海洋和大气）之间全球（地球化学）物质通量的重要界面。由于缺乏对陆地表面地球化学成分的了解，人们尚不清楚地壳的地球化学演化如何受到其性质的影响。因此，这里提供了陆地表面地球化学成分的初步估计，可用于进一步分析。根据文献综述计算不同岩性类别的地球化学平均成分，并将其应用于全球岩性图。与上大陆地壳的总体成分比较表明，陆地表面（土壤层以下）的地球化学成分与上大陆地壳的假设平均值显着不同。具体来说，元素 Ca、S、C、Cl 和 Mg 在陆地表面富集，而 Na 则被耗尽（可能还有 K）。对这些结果的分析提供了进一步的证据，表明化学风化、海洋环境中矿物质的化学蚀变、生物地球化学过程（例如沉积物中的硫酸盐还原和生物矿化）和蒸发岩沉积对于地质时间尺度上陆地表面的地球化学成分非常重要。大量碳酸盐向陆地表面的移动被认为是观察到的钙差异的主要过程。由于陆地表面碳酸盐丰度的突然而显着的变化可能会影响地质时间尺度上化学风化的二氧化碳消耗率，因此建议进行碳循环、精细的空间分辨分析。这应该包括认识目前低于海平面的陆架区域的地球化学成分。
The terrestrial surface, the “skin of the earth”, is an important interface for global (geochemical) material fluxes between major reservoirs of the Earth system: continental and oceanic crust, ocean and atmosphere. Because of a lack in knowledge of the geochemical composition of the terrestrial surface, it is not well understood how the geochemical evolution of the Earth’s crust is impacted by its properties. Therefore, here a first estimate of the geochemical composition of the terrestrial surface is provided, which can be used for further analysis. The geochemical average compositions of distinct lithological classes are calculated based on a literature review and applied to a global lithological map. Comparison with the bulk composition of the upper continental crust shows that the geochemical composition of the terrestrial surface (below the soil horizons) is significantly different from the assumed average of the upper continental crust. Specifically, the elements Ca, S, C, Cl and Mg are enriched at the terrestrial surface, while Na is depleted (and probably K). Analysis of these results provide further evidence that chemical weathering, chemical alteration of minerals in marine settings, biogeochemical processes (e.g. sulphate reduction in sediments and biomineralization) and evaporite deposition are important for the geochemical composition of the terrestrial surface on geological time scales. The movement of significant amounts of carbonate to the terrestrial surface is identified as the major process for observed Ca-differences. Because abrupt and significant changes of the carbonate abundance on the terrestrial surface are likely influencing CO2-consumption rates by chemical weathering on geological time scales and thus the carbon cycle, refined, spatially resolved analysis is suggested. This should include the recognition of the geochemical composition of the shelf areas, now being below sea level.