The Use of Volatile Constituents in Geothermal Fluids for Assessing the Type, Potential and Near Surface Permeability of a Geothermal System: the Broadlands Geothermal Area, N.Z.

Abstract

Volatile constituents surveys were conducted to evalute the suitability as geochemical indicators in a gassy system; Broadlands, New Zealand. were collected from many places across sys for soil Hg, soil air Hg, CO, and Rn and Tn, respectively. The map was compared with the local structure including fault localities and stratigraphy. Comparison was also made with the physical conditions in the aquifer including near surface temperatures and 300 and 600 m isotherms. Samples Zones of high concentrations of volatile components on the western side of the system appeared to correspond with distinctive geological and physical structures and anomalies, but not so obvious on the eastern side except Hg in soil air. This may result from the thick sequence of low porosity and permeability lacustrine sandstone and tstone beds (Huka Falls Formation) which occur in the east.