Use of Radon and Carbon Dioxide in Geochemical Exploration -- Case Study of Silali Geothermal Prospect, Kenya

Abstract

Anomalous concentrations of indicator gas components in subsurface air are related to the geological structure and geochemical environment of regions under consideration. Intensity of gas flow, its composition and isotope ratio of some of its components radically change in periods of seismic activity. Gas surveying in combination with other geochemical, geophysical and geological methods can be applied to fulfilling a number of needs of geological prospecting. High carbon dioxide concentration in the soil gas in the Silali geothermal prospect was observed around the south, south east, north and north-eastern flanks of the caldera areas that coincide with the deep seated faults where the source may be a magmatic body. A NE-SW and N-S trend emerges in areas of high radon distribution. Soil gas survey values are consistent with surface manifestations showing a permeable area with somewhat elevated soil gas concentration on the south eastern side of the caldera.