volatile-bearing silicate melts; compressiblity and equation of state; viscosity; Brillouin spectroscopy; Infrared spectroscopy; diamond anvil cell; compressibility and equation of state
Seifert Rita, Malfait Wim J, Petitgirard Sylvain, Sanchez-Valle Carmen (2013), Density of phonolitic magmas and time scales of crystal fractionation in magma chambers, in Earth and Planetary Science Letters
, 381, 12-20.
Malfait Wim J, Sanchez-Valle Carmen (2013), Effect of water and network connectivity on glass elasticity and melt fragility, in Chemical Geology
, 346, 72-80.
Malfait WJ, Sanchez-Valle C, Ardia P, Medard E, Lerch P (2011), Compositional dependent compressibility of dissolved water in silicate glasses, in AMERICAN MINERALOGIST
, 96(8-9), 1402-1409.
Seifert Rita, Malfait Wim J, Lerch Philippe, Sanchez-Valle Carmen, Partial molar volume and compressibility of dissolved CO2 in glasses with magmatic compositions, in Chemical Geology
Knowledge of density, compressibility and viscosity of volatile-bearing silicate melts under relevant pressure and temperature conditions is essential for understanding the dynamics of magmatic systems in the lower crusts and upper mantle. For example, the density contrast between the melt and the surrounding rocks provides the driving force for the rising of the melts within the crust, controls the stratification of igneous bodies, melt segregation as well as fractionation and partial melting processes. However, the determination of these properties at simultaneous high-pressure, high-temperature conditions is not straightforward and data is available for a very limited range of pressures, temperatures and compositions.It is therefore the aim of this experimental proposal to investigate the elastic, viscoelastic properties and speciation of H2O- and CO2-bearing silicate melts at high pressure and temperature conditions (5 GPa and 1000 °C) using Brillouin scattering and Infrared spectroscopy combined with the hydrothermal diamond anvil cell (HDAC). Project A will focus on the investigation of the elasticity and viscosity of water-bearing rhyolitic melts. Project B will build on the methodologies developed in Project A and will focus on the volumetric properties and speciation of CO2 bearing glasses and melts.Project A: EQUATION OF STATE AND VISCOELASTIC PROPERTIES OF HYDROUS SILICATE MELTSThis project aims at the experimental determination of the equation of state of hydrous rhyolitic melts at high pressure and temperature conditions from acoustic velocity measurements using Brillouin scattering spectroscopy in the diamond anvil cell. The results of this study will provide first constrains on the effect of water on the density and compressibility of these analogs for melts in the crust and the upper mantle. In addition, we will apply Brillouin spectroscopy in the HDAC to investigate the viscoelastic properties of hydrous rhyolites and will provide further constrains on the viscosity and relaxation times for silicate melts at high pressure and temperature conditions. Project B: COMPRESSIBILITY AND SPECIATION OF CARBON-BEARING SILICATE GLASSES AND MELTSThis project will investigate the volumetric effects of dissolved molecular CO2 and carbonate groups on silicate melts. In the first phase, the elastic properties of both hydrous and anhydrous carbon-bearing rhyolitic, andesitic and basaltic glasses at ambient conditions will be investigated using Brillouin scattering spectroscopy. These measurements will provide the first constrain on the partial molar volume and compressibility of the dissolved carbon species (CO2,mol and CO32-). Following the approach developed in Project A, the influence of carbon on the density of rhyolitic melts at high P-T conditions will be further determine. Preliminary investigation of the speciation of dissolved carbon species will be conducted using Infrared spectroscopy and continued during the extension of this proposal.