The interior structure of Mars: Implications from SNC meteorites

Sohl, F.; Spohn, Tilman

doi:10.1029/96je03419

Cited by 241 publications

(273 citation statements)

References 68 publications

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“…For comparison, I focus on two seismological models of Mars' interior developed by Sohl and Spohn (1997) and by Rivoldini et al (2011). The approaches they took to construct the models were similar, using meteorite-based compositional information to predict the mineral assemblages as a function of radius and hence the radial density profile, refining the internal temperature profiles until a match was achieved to the basic planetological data (radius, moment of inertia and k 2 Love number).…”

Section: Seismologymentioning

confidence: 99%

Mars core structure—concise review and anticipated insights from InSight

Helffrich

2017

Prog Earth Planet Sci

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This review summarizes the knowledge of Mars' interior structure, its inferred composition, and the anticipated seismological properties arising from its composition with particular focus on Mars' core. The emphasis on the core stems from the unusual morphology of the liquidus diagram of iron at moderate pressures when enriched in sulfur. From a fairly detailed liquidus diagram constructed from experimental studies, I identify a set of processes that could act within Mars' core: an iron "snow" from the core-mantle boundary's surface and a Fe 3−x S 2 "ground fog" forming at the base of the core. Depending on temperature and bulk sulfur composition, these could form an inner core or could stratify the outer core by enriching it in sulfur, or both. Core stratification could be one explanation for the extinction of Mars' magnetic field early in the planet's history, and I demonstrate the feasibility of this mechanism. The crystallization processes in the core could be observable in the seismic data that the future Mars geophysical mission, InSight, is planned to provide. The core size, the presence of an inner core, and the wavespeed profile of the outer core, whose radial derivative provides a proxy for changes in composition, are key observables to seek.

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Section: Seismologymentioning

confidence: 99%

Mars core structure—concise review and anticipated insights from InSight

Helffrich

2017

Prog Earth Planet Sci

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“…Cratering records seem to bear this out (Chassefière et al 2007), as they do for the weak-to-absent crustal magnetization of the Northern hemispheric dichotomy and the Argyre and Hellas impact basins Whaler and Purucker 2005). Sohl and Spohn (1997). ν T , ν MAC , and ν CIA show three families of potential dynamos driven by different types of flows (see text).…”

Section: Resultsmentioning

confidence: 99%

“…First-order constraints on the planetary Fe/Si ratio (Rivoldini et al 2011;Sohl and Spohn 1997) will be provided by the radius of Mars' core, which will be evident from core-reflected P and S (PcP and ScS) and core penetrating (SKS, SKKS) travel times. The next most important seismic observation relevant for dynamo activity will be the presence or absence of an inner core.…”

Section: Resultsmentioning

confidence: 99%

“…We need R m to be greater than ∼40 for dynamo activity to ensue (Olson and Christensen 2006). Silicate melt conductivity data is somewhat sparse, so I use 1 atm values for basaltic melt from Pommier et al (2010) evaluated at a temperature of 1700 K, which, according to Sohl and Spohn (1997), is a characteristic temperature in Mars' mid-mantle. This indicates a value for σ of 8.9-22.9 S m −1 .…”

Section: Methods/experimentalmentioning

confidence: 99%

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Feasibility of a magma ocean dynamo on Mars

Helffrich

2017

Prog Earth Planet Sci

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Crustal magnetization of rocks in regions of Mars surface testifies to an era of dynamo activity. I examine the possibility that the dynamo that operated then, in the first 400-600 Ma after Mars formed, was powered by a crystallizing subsurface magma ocean. Of the ways that a magma ocean dynamo could operate, on Mars only turbulent and magnetostrophic dynamos seem feasible; geostrophic dynamos do not seem so unless very high heat flows, 100-1000 times present, are invoked. Given the anticipated information from the future InSight lander mission, it will be difficult to assess where the dynamo originated unless an inner core is discovered, rendering the dynamo likely to have operated in the core.

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“…[11] Refer to Sohl and Spohn [1997] for the set of core liquidus parameters used in this study and to Stevenson et al [1983] for core adiabat parameters.…”

Section: Corementioning

confidence: 99%

Thermal evolution of Mercury: Effects of volcanic heat‐piping

Multhaup¹

2009

Geophysical Research Letters

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[1] A 1D thermal evolution model of Mercury is presented. It accounts for stagnant lid convection, mantle differentiation and inner core growth. Early MESSENGER results indicate that-contrary to prior conclusions drawn from Mariner 10 imagery-volcanism has indeed played a significant role in Mercury's past. To study the effects of mantle heat bypassing the stagnant lid by means of volcanic heat-piping, contrasting end-member models are considered. Results show how break-down of mantle convection and onset of inner core growth are influenced by the mode of heat removal. Structural models of present day Mercury are presented. Their dependence on the core sulphur contents predominates that on the choice of mantle heat removal. However, the latter clearly controls the timing of thermal history events.

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The interior structure of Mars: Implications from SNC meteorites

Cited by 241 publications

References 68 publications

Mars core structure—concise review and anticipated insights from InSight

Mars core structure—concise review and anticipated insights from InSight

Feasibility of a magma ocean dynamo on Mars

Thermal evolution of Mercury: Effects of volcanic heat‐piping

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