Element geochemistry of weathering profile of dolomitite and its implications for the average chemical composition of the upper-continental crust |
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| Authors: | Hongbing Ji Ziyuan Ouyang Shijie Wang and Dequan Zhou |
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| Institution: | (1) State Key Laboratory of Environment Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 550002 Guiyang, China |
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| Abstract: | Geochemical behavior of chemical elements is studied in a dolomitite weathering profile in upland of karst terrain in northern
Guizhou. Two stages can be recognized during the process ofin situ weathering of dolomitite: the stage of sedentary accumulation of leaching residue of dolomitite and the stage of chemical
weathering evolution of sedentary soil. Ni, Cr, Mo, W and Ti are the least mobile elements with reference to Al. The geochemical
behavior of REE is similar to that observed in weathering of other types of rocks. Fractionation of REE is noticed during
weathering, and the two layers of REE enrichments are thought to result from downward movement of the weathering front in
response to changes in the environment. It is considered that the chemistry of the upper part of the profile, which was more
intensively weathered, is representative of the mobile components of the upper curst at the time the dolomitite was formed,
while the less weathered lower profile is chemically representative of the immobile constitution. Like glacial till and loess,
the “insoluble” materials in carbonate rocks originating from chemical sedimentation may also provide valuable information
about the average chemical composition of the upper continental crust. |
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| Keywords: | weathering profile element geochemistry average chemical composition of the upper continental crust dolomitite |
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