Characterization of an exhumed high-temperature hydrothermal system and its application for deep geothermal exploration: An example from Terre-de-Haut Island (Guadeloupe archipelago, Lesser Antilles volcanic arc)

We present integrated structural, petrological, mineralogical and geochemical investigations conducted on an exhumed hydrothermal system identified in Terre-de-Haut Island (Guadeloupe archipelago). This work demonstrates, for the first time, the occurrence of ductile shear zones, marked by the development of spaced schistosity planes generated by pressure-solution processes. We unravel first that the development of spaced schistosity is coeval with high-temperature hydrothermalism (approximately 350 °C) and second that this hydrothermal alteration occurred at a depth of less than 2 km. We highlight, at shallow crustal depths, the record of both vertical and lateral fluid pathways in the studied volcanic arc. Finally, combining this new dataset with the large number of published surface data obtained in the active geothermal system of Bouillante, we propose a conceptual scheme for the studied fossil reservoir to document the roots of magmatic arc-related active geothermal systems and to introduce new perspectives for deep geothermal exploration.