Desert terrains in northern China are covered by widespread regolith sediments which mask geochemical signals from ore bodies and are major obstacles to mineral exploration. There is a critical need to study the verti...Desert terrains in northern China are covered by widespread regolith sediments which mask geochemical signals from ore bodies and are major obstacles to mineral exploration. There is a critical need to study the vertical distribution of elements in this regolith and to establish optimum sampling and analytical methods. The aim of this study is to understand the dispersion and variation of elements throughout the cover in a vertical profile. The results demonstrate that the main elements show a distribution pattern of enrichment in clay layers in the vertical profile, i.e., most elements tend to be enriched in the most upper part of the profile above the orebodies except for some elements like Cu, Ca and Ag. Meanwhile, both fine (-160 mesh) and coarse (+20 mesh) fraction samples from clay-rich horizons are favorable samples and selective leaching of the elements absorbed on clays or oxide coatings is effective for localizing buried deposits. The distribution of active Cu and Mo is quite different because chalcopyrite is weathered into Cu sulfate and CuCO3, and is precipitated in alkaline environments in a layer below close to the surface. Mo is soluble in the alkaline environment so it can penetrate the caliche layer and be enriched on the surface of soil enriched with weakly cemented clay.展开更多
基金supported by Department of Science and Technology of Shanxi Province (Project No. 2009021007-1)National Natural Science Foundation of China (Project No. 41103052/D0309)
文摘Desert terrains in northern China are covered by widespread regolith sediments which mask geochemical signals from ore bodies and are major obstacles to mineral exploration. There is a critical need to study the vertical distribution of elements in this regolith and to establish optimum sampling and analytical methods. The aim of this study is to understand the dispersion and variation of elements throughout the cover in a vertical profile. The results demonstrate that the main elements show a distribution pattern of enrichment in clay layers in the vertical profile, i.e., most elements tend to be enriched in the most upper part of the profile above the orebodies except for some elements like Cu, Ca and Ag. Meanwhile, both fine (-160 mesh) and coarse (+20 mesh) fraction samples from clay-rich horizons are favorable samples and selective leaching of the elements absorbed on clays or oxide coatings is effective for localizing buried deposits. The distribution of active Cu and Mo is quite different because chalcopyrite is weathered into Cu sulfate and CuCO3, and is precipitated in alkaline environments in a layer below close to the surface. Mo is soluble in the alkaline environment so it can penetrate the caliche layer and be enriched on the surface of soil enriched with weakly cemented clay.
