Characteristics of particles in groundwater and their prospecting significance for the Shijiangshan Pb-Zn-Ag deposit, Inner Mongolia, China

The Shijiangshan concealed deposit in Inner Mongolia, China is located in a semi-arid region with a thick sediment layer on the surface. Samples of particles from deep and shallow groundwater in the deposit were analyzed by transmission electron microscopy (TEM). Corresponding fault gouge and oxide ore powder were collected and analyzed at the same time. These particles had sizes ranging from 5 to 400 nm and contained metallogenic elements, such as Pb, Zn, As, Cu, and Ag. Groundwater particles can reflect the properties of the deep concealed ores because the metal-bearing particles in the groundwater are similar in composition to the deep ores. In this study, particles with a carbon film covering their surface were discovered in groundwater. The carbon coating helped particles to remain in their primitive state, and thus, retain the more direct metallogenic information. Shallow groundwater particles can be used to predict the composition of deep concealed ore deposits. In thick overburdened areas, where local geochemical information on abnormal elemental levels is not obvious and geophysical prospecting methods may have multiple solutions, the accuracy of prospecting can be improved by using particles in groundwater that provide concealed orebody information, making such particles very important for prospecting.