52nd Lunar and Planetary Science Conference 2021 (LPI Contrib. No. 2548) 1929.pdf BRINE EVOLUTION AND TRANSPORT-DRIVEN FRACTIONATION OF OCEAN FLUIDS WITHIN EUROPA’S ICY SHELL. M. G. Fox-Powell1, J. Semprich1, N. Ramkissoon1, J. J. Buffo2, S. D. Vance3, S. P. 1 1 1 Schwenzer , V. K. Pearson . AstrobiologyOU, Open University, Walton Hall, Milton Keynes, UK MK7 6AA,
[email protected]; 2Dartmouth College, Hanover, NH, USA; 3Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA. Introduction: Constraining the composition of magnesium were systematically varied independently Europa’s subsurface ocean is a vital step in between 0.001 and 0.499. The relative abundances of all understanding the moon’s evolution and potential other ions were kept constant, fixed according to the habitability. Models of water-rock interaction at model of [1]. The total salinities of the hypothetical Europa’s seafloor indicate that a sulfate-rich ocean oceans were also kept constant (here reported at should be expected [1,2], but recent Earth-based terrestrial seawater salinity; 34 g kg-1), to allow direct telescope observations suggest that sodium and comparison of solid phase formation temperatures as a magnesium-chloride salts, not sulfates, dominate function of fluid composition alone. geologically young regions where exchange with the subsurface may have taken place [3,4]. Fractional Results & Discussion: Equilibrium freezing. If crystallization of ocean fluids during freezing can act to ocean-derived fluids are transported in a manner that enrich chlorides within ice, even from sulfate- allows residual brines to remain in equilibrium with dominated fluids [5], offering the possibility to precipitated phases, MgCl2 minerals only form from 2+ 2- reconcile these views.