Elusive Hot Magmatic Brines in the Lesser Antilles: Compositions, Properties and Detectability – MAGBRINES

In arc settings, magmas release large quantities of fluids into the upper crust (< 10 km). Among these fluids, high temperature (>400°C), hypersaline and conductive brines are of crucial interest in the framework the transition to more sustainable energy because their geothermal as well as metallic potentials (of the order of Mt of Cu for an active volcano like Montserrat) seem exceptional.
However, several knowledge gaps prevent an inventory of these resources and the planning of putative sustainable exploitations: How are these magmatic brines formed? Is there a process that concentrates and localizes them in the (peri)magmatic environment? Can we detect them using their geoelectric signatures? what is their metal contents and can we relate them to the metal contents of the magmas that are the sources of these fluids? To answer these questions, MAGBRINES proposes a series of synergistic actions involving volcanologists, geophysicists, specialists in the mechanics of hot and dense fluids, specialists in the thermodynamic modeling of these fluids and specialists in numerical and experimental simulation of these systems. This synergy will allow the study of magmatic brines from the molecular to the kilometer scale. This consortium involving 4 geographically close research institutions, between Orléans (CNRS, University of Orléans and BRGM) and Paris (Sorbonne University and ENS), will determine the properties, compositions, conditions of formation and focusing of these brines and their detectability by geophysical methods. This project will be deployed in the magmatic context of the Lesser French Antilles and should ultimately allow a quantitative inventory of resources in terms of heat and critical metals on a regional scale. MAGBRINES will also develop a collaboration with Oxford on the magmatic brines of Montserrat and Dominica.