Tracking Magmatic Hydrogen Sulfur Circulations Using Electrical Impedance: Complex Electrical Properties of Core Samples at the Krafla Volcano, Iceland

Interaction of H₂S escaping from magma and basaltic rocks leads to pyrite mineralization, witnessing active hydrothermal circulation. We study the possibility to track this process using geoelectrical methods. Complex conductivity spectra of 30 core samples from the Krafla volcano, Iceland, measured in the laboratory, indicate that pyrite can be discriminated from other minerals present in volcanic environments, such as iron oxides and clays. Joint evaluation of the maximum phase angle of electrical impedance and its real part at low frequency is required. The volume of metallic particles (pyrite or iron oxides) can be estimated from the maximum phase angle, but a decrease of the maximum phase angle with increased fluid conductivity or smectite volume is also observed and needs to be considered in the estimation. The laboratory observations can guide interpretation of field observations for estimation of pyrite volume in volcanic environments.