Evidence for a carbon-rich Mercury from the distribution of low-reflectance material (LRM) associated with large impact basins

Lark, L.; Head, J. W.; Huber, Christian

doi:10.1016/j.epsl.2023.118192

Cited by 3 publications

(4 citation statements)

References 68 publications

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“…2–4 wt% 2 , 3 , although a recent reinvestigation of the data suggests lower concentrations (<1 wt.%) 4 . The close association of graphite with lower crustal material observed in deep craters supports an endogenous origin for graphite 5 , 6 and rules out major exogeneous contributions by comets 7 .…”

Section: Introductionsupporting

confidence: 53%

“…S7 ). However, carbon solubility in the magma ocean does fix the lower limit for the thickness of the primordial graphite crust as graphite delivered to Mercury by the building blocks may have accumulated at the surface of the molten planet at carbon-saturation 6 .…”

Section: Resultsmentioning

confidence: 99%

“…Because of the highly reduced conditions that prevailed during Mercury’s differentiation (in the range IW − 2.6 to IW − 7.3 8 , 9 , reported in log units relative to iron-wüstite thermodynamic equilibrium, IW), light elements in Mercury’s iron core are thought to be dominated by silicon, sulfur, and carbon 10 – 13 . Although carbon likely degassed from the magma ocean as CO 2 , CO, and CH 4 species 14 – 18 and was lost to space, the abundance of graphite in the Mercurian crust indicates that the planet remained saturated in a carbon phase during metal-silicate differentiation, core formation, and the entirety of magma ocean crystallization 6 . Additionally, because the solubility of carbon in silicate melt is exceptionally low under reduced conditions 19 , 20 , a significant amount of excess carbon should have been available to contribute to the formation of a graphite flotation crust.…”

Section: Introductionmentioning

confidence: 99%

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A diamond-bearing core-mantle boundary on Mercury

Xu,

Lin,

et al. 2024

Nat Commun

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Abundant carbon was identified on Mercury by MESSENGER, which is interpreted as the remnant of a primordial graphite flotation crust, suggesting that the magma ocean and core were saturated in carbon. We re-evaluate carbon speciation in Mercury’s interior in light of the high pressure-temperature experiments, thermodynamic models and the most recent geophysical models of the internal structure of the planet. Although a sulfur-free melt would have been in the stability field of graphite, sulfur dissolution in the melt under the unique reduced conditions depressed the sulfur-rich liquidus to temperatures spanning the graphite-diamond transition. Here we show it is possible, though statistically unlikely, that diamond was stable in the magma ocean. However, the formation of a solid inner core caused diamond to crystallize from the cooling molten core and formation of a diamond layer becoming thicker with time.

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Section: Introductionsupporting

confidence: 53%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A diamond-bearing core-mantle boundary on Mercury

Xu,

Lin,

et al. 2024

Nat Commun

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“…% C, similarly to the effect played by sulfur's presence (Edmund Steenstra, Seegers, et al, 2020). The most recent estimations of carbon (C), obtained from the study of low-reflectance materials (LRM; see Lark et al (2023) for details), suggest that the core of Mercury contains between 0.5 wt.% if it is extremely rich in Si, up to 1-4 wt.% of C, a value in agreement with geodetic data (Knibbe & van Hoolst, 2021). If the mantle and core of Mercury have equilibrated with respect to C, then the core must have preferentially partitioned it, resulting in a reduced quantity of Si in the core.…”

Section: Implications For the Core Composition: The Role Of Carbonmentioning

confidence: 99%

Mantle Mineralogy of Reduced Sub‐Earths Exoplanets and Exo‐Mercuries

Cioria,

Mitri,

Connolly

et al. 2024

JGR Planets

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The mineralogy of planetary mantles formed under reducing conditions, as documented in the inner regions of the solar system, is not well constrained. We present thermodynamic models of mineral assemblages that would constitute the mantles of exo‐Mercuries. We investigated reduced materials such as enstatite chondrites, CH, and CB chondrites, and aubrites, as precursor bulk compositions in phase equilibrium modeling. The resulting isochemical phase diagram sections indicate that dominant phases in these reduced mantles would be pyroxenes rather than olivine, contrasting with the olivine‐rich mantles found within Earth, Mars, and Venus. The pyroxene abundances in the modeled mantles assemblages depend on the silica content shown by precursor materials. The silica abundance in the mantle is closely related to Si abundance in the core, particularly in reduced environments. In addition, we propose that pyroxene‐rich mantles exhibit more vigorous convective and tectonic activity than olivine‐rich mantles, given that pyroxene‐rich mantles would have lower viscosity and a lower solidus temperature (Ts).

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Mercury

McCubbin,

Anzures

2025

Treatise on Geochemistry

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Evidence for a carbon-rich Mercury from the distribution of low-reflectance material (LRM) associated with large impact basins

Cited by 3 publications

References 68 publications

A diamond-bearing core-mantle boundary on Mercury

A diamond-bearing core-mantle boundary on Mercury

Mantle Mineralogy of Reduced Sub‐Earths Exoplanets and Exo‐Mercuries

Mercury

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