Speaker: Claire Bouligand
ISTerre, Université Grenoble Alpes
Magnetic surveys can provide insights in geothermal systems as they can be used to assess heat flow, image structures that facilitate fluid flow and map the distribution of buried hydrothermal alteration. Because the interpretation of magnetic surveys is non-unique, the use of simplifying assumptions on the distribution of crustal magnetization is necessary. First, we present an assessment of crustal temperatures in the western US based on the spectral analysis of a compilation of aeromagnetic surveys. To this end, we assume that the bottom of magnetic sources correspond to the Curie temperature isotherm and we use a fractal model for crustal magnetization. Second, we use airborne and ground magnetic surveys acquired over thermal areas of Yellowstone National Park to image geological structures and hydrothermal alteration. To this end, magnetic anomalies are interpreted using a combination of 3D forward models and 2D inversions of surfaces characterized by a sharp contrast of magnetization.