Soil air carbon dioxide and oxygen measurements as a guide to concealed mineralization in semi-arid and arid regions

The differences between the CO2 and O2 concentrations in soil air and atmospheric air have been measured where sulfide mineralization occurs beneath transported exotic overburden in semi-arid and arid areas of the USA, South West Africa (Namibia) and Saudi Arabia. These mineralizations are reflected near surface by anomalous levels of CO2 and O2 in soil air, whereas in most cases heavy-metal anomalies are absent. The normal background variability of CO2 and O2 in soil air falls with increasing aridity, and anomaly definition improves with increasing aridity. Thus soil air CO2 and O2 data are potentially useful in exploring for concealed mineralization, especially in regions with an arid climate or conspicuous dry season.