000005618 001__ 5618
000005618 005__ 20220125202735.0
000005618 0247_ $$2DOI$$a10.1016/j.epsl.2021.117330
000005618 037__ $$aSCART-2022-0024
000005618 100__ $$aKhan, A. 
000005618 245__ $$aGeophysical and cosmochemical evidence for a volatile-rich Mars
000005618 260__ $$c2022
000005618 520__ $$aConstraints on the composition of Mars principally derive from chemical analyses of a set of Martian meteorites that rely either on determinations of their refractory element abundances or isotopic compositions. Both approaches, however, lead to models of Mars that are unable to self-consistently explain major element chemistry and match its observed geophysical properties, unless ad hoc adjustments to key parameters, namely, bulk Fe/Si ratio, core composition, and/or core size are made. Here, we combine geophysical observations, including high-quality seismic data acquired with the InSight mission, with a cosmochemical model to constrain the composition of Mars. We find that the FeO content of Mars' mantle is 13.7$\pm$0.4 wt{\%}, corresponding to a Mg{\#} of 0.81$\pm$0.01. Because of the lower FeO content of the mantle, compared with previous estimates, we obtain a higher mean core density of 6150$\pm$46 kg/m3 than predicted by recent seismic observations, yet our estimate for the core radius remains consistent around 1840$\pm$10 km, corresponding to a core mass fraction of 0.250$\pm$0.005. Relying on cosmochemical constraints, volatile element behaviour, and planetary building blocks that match geophysical and isotopic signatures of Martian meteorites, we find that the liquid core is made up of 88.4$\pm$3.9 wt{\%} Fe-Ni-Co with light elements making up the rest. To match the mean core density constraint, we predict, based on experimentally-determined thermodynamic solution models, a light element abundance in the range of ≈9 wt{\%} S, ⩾3 wt{\%} C, ⩽2.5 wt{\%} O, and ⩽0.5 wt{\%} H, supporting the notion of a volatile-rich Mars. To accumulate sufficient amounts of these volatile elements, Mars must have formed before the nebular gas dispersed and/or, relative to Earth, accreted a higher proportion of planetesimals from the outer protoplanetary disk where volatiles condensed more readily.
000005618 594__ $$aNO
000005618 700__ $$aSossi, P. A. 
000005618 700__ $$aLiebske, C. 
000005618 700__ $$aRivoldini, A. 
000005618 700__ $$aGiardini, D.
000005618 773__ $$pEarth and Planetary Science Letters$$v578$$y2022
000005618 8560_ $$fattilio.rivoldini@observatoire.be
000005618 8564_ $$s4354382$$uhttps://publi2-as.oma.be/record/5618/files/Khan2022uh85.pdf
000005618 8564_ $$s17885$$uhttps://publi2-as.oma.be/record/5618/files/Khan2022uh85.gif?subformat=icon$$xicon
000005618 8564_ $$s20271$$uhttps://publi2-as.oma.be/record/5618/files/Khan2022uh85.jpg?subformat=icon-180$$xicon-180
000005618 905__ $$apublished in
000005618 980__ $$aREFERD