Thermal-Compositional Evolution of Europa’s Interior and Ocean Since Accretion

Europa’s compositional evolution is not well constrained. Observations only provide approximations of the current interior structure of Europa. However, dynamic models [Hussmann & Spohn 2004] resolve the magnitude of interior heating produced by tidal interaction over time. We couple the heat production to thermodynamic and chemical equilibrium models Perple_X [Connolly 2005], Rcrust [Mayne+ 2016] and CHIM-XPT [Reed 1998] to compute compositional changes of the interior and ocean. Assuming that Europa's interior is not molten now, a Fe core could have accommodated up to 24 wt % S during accretion, assuming chondritic accretion material. However, a metal-silicate segregated magma ocean was needed to allow such high S content in the core. More likely, accretion proceeded with low impact rates that allowed heat dissipation. Based on this and experimental metal-silicate partition behavior, Europa’s core contains ~1 wt % S. Two mantle melting events were calculated corresponding to putative events in Europa’s ...