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A geophysical perspective on the bulk composition of Mars

Khan, A. and Liebske, C. and Rozel, A. and Rivoldini, A. and Nimmo, Francis and Connolly, J.A.D. and Plesa, Ana-Catalina and Giardini, D. (2018) A geophysical perspective on the bulk composition of Mars. JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS, 123 (2), pp. 576-611. Wiley. DOI: 10.1002/2017JE005371 ISSN 2169-9097

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We invert the Martian tidal response and mean mass and moment of inertia for chemical composition, thermal state, and interior structure. The inversion combines phase equilibrium computations with a laboratory-based viscoelastic dissipation model. The rheological model, which is based on measurements of anhydrous and melt-free olivine, is both temperature and grain size sensitive and imposes strong constraints on interior structure. The bottom of the lithosphere, defined as the location where the conductive geotherm meets the mantle adiabat, occurs deep within the upper mantle (∼250–500 km depth) resulting in apparent upper mantle low-velocity zones. Assuming an Fe-FeS core, our results indicate: 1) a Mantle with a Mg# (molar Mg/Mg+Fe) of ∼0.75 in agreement with earlier geochemical estimates based on analysis of Martian meteorites; 2) absence of bridgmanite- and ferropericlase-dominated basal layer; 3) core compositions (13.5–16 wt% S), core radii (1640–1740 km), and core-mantle-boundary temperatures (1560–1660 ∘ C) that, together with the eutectic-like core compositions, suggest the core is liquid; and 4) bulk Martian compositions that are overall chondritic with a Fe/Si (wt ratio) of 1.63–1.68. We show that the inversion results can be used in tandem with geodynamic simulations to identify plausible geodynamic scenarios and parameters. Specifically, we find that the inversion results are reproduced by stagnant lid convection models for a range of initial viscosities (∼1019–1020 Pa·s) and radioactive element partitioning between crust and mantle around 0.001. The geodynamic models predict a mean surface heat flow between 15–25 mW/m2.

Item URL in elib:https://elib.dlr.de/116647/
Document Type:Article
Title:A geophysical perspective on the bulk composition of Mars
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Khan, A.institut für geophysik, eth zürich, switzerlandUNSPECIFIED
Liebske, C.Institute of Geochemistry and Petrology, ETH Zürich, SwitzerlandUNSPECIFIED
Rozel, A.Institute of Geophysics, ETH Zürich, SwitzerlandUNSPECIFIED
Rivoldini, A.royal observatory of belgium and université catholique de louvain, earth and life institute (eli), georges lemaître centre for earth and climate research (teclim), belgiumUNSPECIFIED
Nimmo, Francisdepartment of earth and planetary sciences, university of california santa cruz, santa cruz, ca 95064, usaUNSPECIFIED
Connolly, J.A.D.Institute of Geochemistry and Petrology, ETH Zürich, SwitzerlandUNSPECIFIED
Plesa, Ana-CatalinaAna.Plesa (at) dlr.deUNSPECIFIED
Giardini, D.institute of geophysics/swiss seismological service, swiss federal institute of technology, (ethz), honggerberg, ch-3093 zurich, switzerlandUNSPECIFIED
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
DOI :10.1002/2017JE005371
Page Range:pp. 576-611
Keywords:Rheology of the lithosphere and mantle, Elasticity and anelasticity, Composition, Interiors, Mars, Mars, interior structure, Dissipation, Rheology, Mantle temperature, Core size
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Science and Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Erforschung des Weltraums
DLR - Research theme (Project):Project InSight HP3
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research > Planetary Physics
Deposited By: Plesa, Dr. Ana-Catalina
Deposited On:06 Dec 2017 09:04
Last Modified:07 Mar 2019 08:47

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