The Petite Anse-Diamant Geothermal System (Martinique Island, Lesser Antilles): Results of the 2012-2013 Exploration

Alain Gadalia (1) , Jean-Michel Baltassat (1) , Vincent Bouchot (1) , Séverine Caritg-Monnot (1) , Frédérick Gal (1) , Jean-François Girard (1) , Alexis Gutierrez (1) , Thomas Jacob (1) , Guillaume Martelet (1) , Nicolas Coppo (1) , Setareh Rad (1) , Anne-Lise Tailame (1) , Hervé Traineau (2) , Benoit Vittecoq (1) , Pierre Wawrzyniak (1)

1 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)
2 CFG - Compagnie Française de Géothermie

A 2012-2013 additional and combined – geological, hydrogeological, geochemical, geophysical -surface exploration results in a new insight of the Martinique geothermal systems, including Petite Anse – Diamant area. The Petite Anse – Diamanthot spring is located at the foot of a small volcano -Morne Jacqueline – part of a NW-SE volcano-tectonic corridor. The Southern flank of this volcano collapsed leading to the outcrop: 1) A previous neutral, high temperature hydrothermal activity corresponding to a MT conductive layer interpreted as a clay cap of the present geothermal system. The bottom of the conductive layer displays also a doming shape, characterizing the top of geothermal system; 2) A dyke of diorite coinciding with the top of a huge MT resistive body, following the volcanic corridor, and interpreted as a magma intrusion; it generates several on and off-shore spots of magmatic degassing; this intrusive gas –rock may act as a heat source and interact with the geothermal fluid. The Petite Anse spring water is of Na-Cl type due to a seawater contribution. The associated geothermal reservoir temperature is estimated at 190-210°C. The recharge of the system is likely to be low, because of both a bad permeability resulting from the extensive acidic alteration related to previous fumarolic expression, and limited rainfalls. An exploration drilling area is proposed at the North of the Petite Anse village.

Keywords: geothermometers; water-rock interaction; MT resistive body; caprock doming; magmatic degassing; intrusive complex; paleo-geothermal system; Flank collapse

Domains: Geochemistry; Geophysics [physics.geo-ph]

Alain Gadalia, Jean-Michel Baltassat, Vincent Bouchot, Séverine Caritg-Monnot, Frédérick Gal, et al.. The Petite Anse-Diamant Geothermal System (Martinique Island, Lesser Antilles): Results of the 2012-2013 Exploration. World Geothermal Congress 2015, Apr 2015, Melbourne, Australia. ⟨hal-01102469⟩