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2025
ACL
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Marion Louvel, Denis Testemale, Alain Prat, Eric Lahera, William Del-Net, Aneta Slodczyk, Benjamin Langerome, Remi Champallier, Richard Brooker, Anita Cadoux, Jasper Berndt, Jean-Louis Hazemann, 'A transparent IHPV for the in-situ geochemical characterization of magmatic volatile phases and melts', Journal of Volcanology and Geothermal Research 466 108381 (2025) doi:10.1016/j.jvolgeores.2025.108381
Chemical exchanges between magmas and volatile-rich fluids and gases are fundamental processes of magmatic and volcanic activity, but also play a critical role in the formation of various ore deposits. Yet, the composition and properties of the so-called magmatic volatile phases (MVPs) remain elusive, due to difficulties in their sampling, both in natural systems and in experimental laboratories. Here, we present a novel ‘transparent’ internally-heated high-pressure vessel (T-IHPV) that enables the geochemical characterization of coexisting hydrous melts and MVPs in-situ, under typical shallow magmatic conditions. The experimental design is validated through the observation of haplogranite and rhyodacite melting to 900 °C and 130 MPa and the in-situ X-ray absorption (XAS) study of bromine and strontium distribution and speciation in the haplogranite-H2O system to 800 °C and 100 MPa. These preliminary experiments confirm the efficient partitioning of Br in MVPs in differentiated systems (DBrMVP/melt around 41 for haplogranite) and reveal the stability of hydrated Br species instead of HBr in the MVPs. Coupled to other spectroscopic methods (Raman, SAXS/WAXS, XRD), we expect the T-IHPV to shed a new light on the thermodynamics and kinetics of chemical reactions at stake in shallow magmatic and hydrothermal reservoirs.
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