Geogas prospecting for buried deposits under loess overburden: Taking Shenjiayao gold deposit as an example

Abstract

The loess areas cover about 6% of China's land and they are thought to have a high likelihood of hosting valuable mineral resources. General geochemical exploration methods are restricted in this region due to the thick loess overburden. Here, we used geogas prospecting, which has been uniquely developed in China, to test its ability to delineate buried deposits at Shenjiayao gold deposit. Two different media: 5% ultrapure aqua regia and polyurethane foam, were used to sample the geogas in the soil. Based on concentrations and precision in our experiment, the polyfoam seemed to out-perform the aqua regia. To investigate how the anomalies formed, a special carrier was used to sample original substances in the geogas. Nanoscale gold-bearing particles were found both in the geogas, supporting the hypothesis that metallic nanoparticles released from orebodies and altered rocks during weathering process can be transported towards the surface. Besides the evidence of nanoparticles, correlations of elements in ores and geogas indicated the close connection between them. Therefore, our field experiment showed geogas prospecting can be effective in exploration for buried mineral resources.