3D Fault Model of the Bouillante Geothermal Province Interpreted from Onshore and Offshore Structural Knowledge (French West Indies)

Philippe Calcagno (1) , Vincent Bouchot (1) , Isabelle Thinon (1) , Bernard Bourgine (1)

1 BRGM - Bureau de Recherches Géologiques et Minières

The Bouillante area is known for its high-temperature geothermal field which produce electricity in a 15 MWe installed power plant (Guadeloupe Island, French West Indies). This zone is a complex geodynamic area. It stands at the convergence of the major tectonic and volcanic structures of the inner arc of the Lesser Antilles. The two main regional fault systems joining at the Bouillante geothermal field are the NW–SE Montserrat–Bouillante (MB) fault system, and the ESE–WNW to E–W Bouillante–Capesterre (BC) fault system. Two other factors make rather difficult the interpretation of the geological structuration. Firstly, Bouillante is located on the West coast of the Guadeloupe Island. It means that data and observations both from the Island and from the sea are needed. Secondly, a wet tropical climate prevails in that region. That is why exposures suitable for direct structural measurements are almost only found on the seaside where coastal erosion has stripped away the soil. The available data show that, on one hand, faults observed on the field mainly elongate along the E-W direction. On the other hand, offshore structures interpreted from marine seismic lines show a larger range of directions. In order to achieve a coherent interpretation of the Bouillante geothermal area, a 3D fault model is completed from onshore and offshore structural knowledge. A 15 km x 16 km zone crossing the island coastline is investigated down to 2 km depth. The fault network constructed reveals a hierarchy in the family of structures and highlights the prevalence of the NNW-SSE direction, associated with secondary NE-SW-trending structures, and the E-W direction. On a geographical point of view, the modelled faults are gathered in 3 clusters along the coast. The 3D model facilitates a coherent interpretation of the faults in the Bouillante province but this model can also be a cradle for hydro dynamic simulation.

Mots clés: 3D modelling; fault modelling; onshore and offshore combination; geothermal energy; geothermal exploration; Bouillante

Domaines: Géologie appliquée; Modélisation et simulation

Philippe Calcagno, Vincent Bouchot, Isabelle Thinon, Bernard Bourgine. 3D Fault Model of the Bouillante Geothermal Province Interpreted from Onshore and Offshore Structural Knowledge (French West Indies). World Geothermal Congress 2015, Apr 2015, Melbourne, Australia. ⟨hal-01098052⟩