265 9. Defining high enthalpy geothermal drilling target with multi-physics Figure 9.9 Resistivity (Ω/m) profile obtained from the inversion of the electric profile (Pajot et al., 2007). A first interpretation had already been made of the resistivity profile obtained by inversion (Figure 9.9), but it was not complete enough to be integrated as is into the model. In light of the recent data, a new interpretation (Figure 9.10) is proposed, taking into account the identified formations. Figure 9.10 New interpretation of the electric profile. This interpretation aligns with the overall architecture of Petite Terre, where volcanic material cuts through the carbonates, settling on top to form the island. The upper part is therefore composed of resistive trachytic ash and tuff. Below, the carbonated platform is conductive due to the intense water circulation and, in particular, saline intrusions that lower resistivity values. The Dziani lake area shows low resistivity, which extends clearly in depth. However, Dziani Lake is a maar created by phreatomagmatism. Therefore, it is reasonable to think that this low-resistivity zone is a conduit for fluid circulation. A zone of low resistivity, which could be linked to a high permeability zone, could, on the one hand, explain the magma upwelling and, on the other hand, the subsequent water circulation that causes hydrothermalism, leading to the alteration of magmatic rocks and thus low resistivity. On the profile, two faults can be interpreted. The first to the south aligns with the one previously interpreted from the field data. This provides additional evidence for its presence, which was previously only inferred from gas emissions. The second interpreted fault dips southwest and forms a small graben in the middle of Petite Terre. To trace this fault on the map, however, another anchor point is needed.
RkJQdWJsaXNoZXIy NjA3NzQ=