000006652 001__ 6652
000006652 005__ 20240124205445.0
000006652 037__ $$aPOSTER-2024-0011
000006652 100__ $$aSamuel, H.
000006652 245__ $$aGeophysical evidence for a compositionally stratified Martian mantle
000006652 260__ $$c2023
000006652 269__ $$c2023-12-12
000006652 500__ $$aDI23B-0034
000006652 520__ $$aThe identification of deep reflected S-waves on Mars has led to the first seismic estimation of a core size of 1830±40 km [1]. However, this relatively large core size requires light element contents incompatible with experimental petrological constraints. In addition, this core size estimate assumes a compositionally homogeneous Martian mantle, at odds with measurements of anomalously slow propagating P-waves diffracted along the core-mantle boundary [2]. Alternatively, Mars' mantle may be heterogeneous as a result of a magma ocean solidification that formed a basal layer enriched in iron and heat-producing elements [3], resulting in the the presence of a molten silicate layer above the core, overlain by a partially molten layer [4]. To determine the planet structures compatible with observations, we performed a probabilistic inversion of seismic data. Our inversion relies on a parameterisation in terms of quantities that influence the thermo-chemical evolution of the planet composed of a liquid iron core, a silicate mantle (with or without a enriched Basal Mantle Layer), and an evolving lithosphere and crust [5]. We show that such a layered Martian mantle is compatible with all geophysical data including (1) deep reflected and diffracted seismic phases from the mantle, (2) weak shear attenuation at seismic frequencies, and (3) Mars' dissipative behaviour at Phobos tides. In particular, our results point to a revised core size of 1650±20 km implying a density of 6.5 g/cm3, 5-8% larger than previous seismic estimates. Using a core equation of state that reproduces experimental data, we show that Mars' core can be explained by fewer, and less abundant, alloying light elements than previously required, in amounts compatible with experimental and cosmochemical constraints. The new density structure is compatible with measurements of Mars' rotation [6]. The layered mantle structure requires external sources to generate the magnetic signatures recorded in Mars' crust. [1] Stähler, S. et al., Science 373 (2021) [2] Posiolova L. et al. Science, 378 (2022) [3] Elkins-Tanton, L. et al., JGR., doi: 10.1029/2005JE002480 (2003) [4] Samuel, H. et al., JGR, doi:10.1029/2020JE006613 (2021) [5] Drilleau, M. et al., JGR, doi:10.1029/2021JE007067 (2022) [6] Le Maistre et al., Nature, doi:10.1038/s41586-023-06150-0 (2023)
000006652 536__ $$a3PRODPLANINT/$$c3PRODPLANINT/$$f3PRODPLANINT
000006652 594__ $$aNO
000006652 700__ $$aDrilleau, M. 
000006652 700__ $$aRivoldini, A. 
000006652 700__ $$aXu, Z.
000006652 700__ $$aHuang, Q.
000006652 700__ $$aGarcia, R. F.
000006652 700__ $$aLekić, V. 
000006652 700__ $$aIrving, J. C. E.
000006652 700__ $$aBadro, J.
000006652 700__ $$aLognonné, P. H.
000006652 700__ $$aConnolly, J. A. D.
000006652 700__ $$aKawamura, T.
000006652 700__ $$aGudkova, T.
000006652 700__ $$aBanerdt, W. B.
000006652 773__ $$tAGU 2013 San Fransisco
000006652 8560_ $$fattilio.rivoldini@ksb-orb.be
000006652 85642 $$ahttps://agu.confex.com/agu/fm23/meetingapp.cgi/Paper/1247115
000006652 8564_ $$s4911092$$uhttp://publi2-as.oma.be/record/6652/files/samuel_et_al_AGU_2023.pdf
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000006652 980__ $$aCPOSTER