ABSTRACT

Several studies have shown that gas flows (namely “geogas”) ascending from the Earth’s interior can, while passing through concelead orebodies, assimilate ore nanoparticles and carry them to the surface. The orebodies might be detected by measuring nanoparticle contents in soil gas or in the atmosphere. However, the mechanism by which geogas carries gold nanoparticles from orebodies to the surface is not well understood. To investigate these migration mechanisms, suspended particles from deep gas in the Hetai gold ore district in southern China were collected, gold nanoparticles artificially added, and the distribution of the gold nanoparticles studied using a transmission electron microscope. This study showed that gold nanoparticles migrate by 1) adsorption onto other particles suspended in the geogas, including needle, spherical and flower-like shaped iron-bearing particles, spherical aluminous particles, and calcite; and 2) in aggregated form.