Geophysical Exploration of High Temperature Geothermal Areas Using Resistivity Methods . Case Study: Theistareykir Area, NE Iceland

Abstract

GEOPHYSICAL EXPLORATION OF HIGH TEMPERATURE GEOTHERMAL AREAS USING RESISTIVITY METHODS CASE STUDY: THEISTAREYKIR AREA,NE ICELAND. Eriya Kahwa Ministry of Energy and Mineral Development Department of Geological Survey and Mines P.O.Box 9 Entebbe UGANDA kahwaeriya@gmail.com ABSTRACT Measuring the electrical resistivity, ρ, of the subsurface is the most powerful geophysical prospecting method in high temperature geothermal exploration and the main method used in delineating geothermal resources. Resistivity surveys using TEM and MT methods have been done in the Theistareykir geothermal area since 2004 and in this work; sixteen TEM and MT soundings on two profiles have been jointly inverted based on 1D models. Cross sections and iso-resistivity maps of the joint inversion models of the TEM and MT data from Theistareykir geothermal area reveal features similar to other high temperature areas in Iceland with a resistive zone reflecting unaltered rock formations, shallow conductive cap and a resistive core reflecting chlorite-epidote alteration. Two deep conductors ( less than 10 Ωm) possibly related to the heat source have been interpreted north of Bóndhólsskarð and north east of Stórihver. Good correlation between the subsurface resistivity and hydrothermal alteration in borehole ThG-05 was confirmed.