The fate of volatiles in magma on mercury
Mercury has been extensively characterized by the NASA MESSENGER spacecraft that was orbiting the planet from 2011 to 2015. The surface of Mercury is covered by lavas and magmatic processes have structured the planet into an extremely large core, a thin mantle and a relatively thick crust, which is highly reduced, iron-depleted, and rich in volatiles. Some volatiles (sulfur and carbon) have been measured at the surface in relatively high abundances compared to other terrestrial planets butthe speciation, role and their fate under highly reducing conditions are still unclear. In this research program, the understanding of the evolution of volatiles in magma on Mercury will be advanced by combining MESSENGER data and laboratory experiments. Relevant data will be obtained from high-temperature and low- to high-pressure experiments using furnaces, presses and multi-anvil apparatus. We will investigate experimentally compositions corresponding to the possible primitive mantle composition, and to surface compositions provided by X-Ray Spectroscopy data from MESSENGER. These recent data provide a unique opportunity to perform innovative experiments under the extremely reducing conditions characteristic for Mercury on sulfides liquid immiscibility, mantle partial melting, and speciation and solubility of volatiles in magmas. Our objectives are to provide new and firm constraints on (1) the P-T position of the solidus of the mantle of Mercury; (2) the speciation, role and fate of carbon and sulfur volatiles in magmas on Mercury and (3) the partitioning of trace elements between sulphide melts (FeS and (Ca,Mg,Fe)S) and silicate melt in the Mercurian mantle.