Mobility of Volatiles in the Earth’s Mantle by Experimental and Numerical Technics

ended

Volatiles cycle plays a critical role in the humanity’s existence by defining the habitability conditions prevailing at the Earth’s surface. Mantle is a major actor of this cycle by hosting considerable proportions of carbon, and also hydrogen. Understanding the exchanges and fluxes of carbon (and water) between the upper mantle and exosphere remains a primary goal in the Earth sciences community, but critically prevented by the lack of fundamental constrains on the mobility and migration rates of volatile-bearing melts (i.e., CO2-H2O-bearing melts) that are important conveyors for the distribution of volatiles. Therefore, the aim of the MoVEMENT project is to combine fundamental constraints on the physical properties (density and viscosity) of volatile-bearing melts with complex modelling to gain a quantitative understanding of the deep volatile cycles and related geophysical processes inside the planet. The applicant will achieve these scientific breakthroughs by combining two novel approaches: first, he will capitalize on new experimental methods at synchrotron sources to acquire missing data on the density and viscosity of carbon-bearing melts at high pressure; second, he will integrate the novel data into rigorous and continuous computer models for the density and viscosity of volatile-bearing melts. The new models will allow predictions of the mobility of volatile-bearing melts in a range of pressure, temperature (20 GPa – 2500 °C ) and compositions, i.e. from carbonatites (CO2-rich melts) to basalts (SiO2-rich melts), that span the conditions for melts stabilized in the upper mantle. Specifically, the results will be applied to quantify volatile-mediated processes in the upper mantle, including the migration/ascent/emplacement of melts through the mantle, ultimately leading to a new understanding of volatile mobility and recycling in the deep Earth.