New Evidences for Transport Mechanism and Case Histories of Geochemical Exploration through Covers

Recent years, a great progress on exploration geochemistry has been made in findings of evidences of nanoparticles of metals and metals in vegetable cells. The findings have provided nanoscale and molecular-level understanding of metal transportation from the concealed ore bodies through the overburden covers. The case history studies from concealed Au, Cu-Ni, Cu-Au-Ag deposits show that these nanoparticles of metals could penetrate through sedimentary, metamorphic and soil covers to the surface. Nanoparticle sampling and selective leaching of oxide coatings are effective to indicate concealed deposits. Case study on sandstone-type uranium deposits show that uranium is converted to uranyl ions (UO₂²⁺) under oxidizing conditions and is sorbed on clay minerals to accumulate in anomalous concentrations, which comprise from 17.9% to 40% of the total U content. Separation of fine-grained clay-rich soils or selective leaching of absorbed U onto clays are effective for deep-penetrating geochemical surveys for sandstone-type uranium deposits.