Trace element partitioning between ilmenite, armalcolite and anhydrous silicate melt: Implications for the formation of lunar high-Ti mare basalts

Parker, M. van Kan; Mason, Paul R.D.; Westrenen, W. van

doi:10.1016/j.gca.2011.04.031

Cited by 22 publications

(4 citation statements)

References 59 publications

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“…A four-bore Al 2 O 3 rod through which thermocouple wires were threaded was placed on the top of MgO rod. Pressure calibration of the assembly was performed by bracketing the albite to jadeite plus quartz and fayalite to ferrosilite plus quartz transitions (van Kan Parker et al 2011). The resulting pressure correction of 3% is consistent with literature data (McDade et al 2002).…”

Section: High-pressure High-temperature Experimentsmentioning

confidence: 99%

Capturing the oxidation of silicon carbide in rocky exoplanetary interiors

Hakim

Westrenen

Dominik

2018

A&A

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Context. Theoretical models predict the condensation of silicon carbide around host stars with C/O ratios higher than 0.65 (cf. C/O Sun = 0.54), in addition to its observations in meteorites, interstellar medium and protoplanetary disks. Consequently, the interiors of rocky exoplanets born from carbon-enriched refractory material are often assumed to contain large amounts of silicon carbide. Aims. Here we aim to investigate the stability of silicon carbide in the interior of carbon-enriched rocky exoplanets and to derive the reaction leading to its transformation. Methods. We performed a high-pressure high-temperature experiment to investigate the reaction between a silicon carbide layer and a layer representative of the bulk composition of a carbon-enriched rocky exoplanet. Results. We report the reaction leading to oxidation of silicon carbide producing quartz, graphite, and molten iron silicide. Combined with previous studies, we show that in order to stabilize silicon carbide, carbon saturation is not sufficient, and a complete reduction of Fe 2`t o Fe 0 in a planetary mantle is required, suggesting that future spectroscopic detection of Fe 2`o r Fe 3`o n the surface of rocky exoplanets would imply the absence of silicon carbide in their interiors.

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Section: High-pressure High-temperature Experimentsmentioning

confidence: 99%

Capturing the oxidation of silicon carbide in rocky exoplanetary interiors

Hakim

Westrenen

Dominik

2018

A&A

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“…A four-bore Al 2 O 3 rod through which thermocouple wires were threaded, was placed on the top of MgO rod. Pressure calibration of the assembly was performed by bracketing the albite to jadeite plus quartz and fayalite to ferrosilite plus quartz transitions (van Kan Parker et al, 2011). The resulting pressure correction of 3% is consistent with literature data (Mc-Dade et al, 2002).…”

Section: Appendix a Experimental Sample Assemblymentioning

confidence: 58%

Mineralogy, Structure, and Habitability of Carbon-Enriched Rocky Exoplanets: A Laboratory Approach

et al. 2019

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Carbon-enriched rocky exoplanets have been proposed around dwarf stars as well as around binary stars, white dwarfs and pulsars. However, the mineralogical make up of such planets is poorly constrained. We performed high-pressure high-temperature laboratory experiments (P = 1´2 GPa, T = 1523´1823 K) on chemical mixtures representative of C-enriched rocky exoplanets based on calculations of protoplanetary disk compositions. These P´T conditions correspond to the deep interiors of Pluto-to Mars-size planets and the upper mantles of larger planets.Our results show that these exoplanets, when fully-differentiated, comprise a metallic core, a silicate mantle and a graphite layer on top of the silicate mantle. Graphite is the dominant carbon-bearing phase at the conditions of our experiments with no traces of silicon carbide or carbonates. The silicate mineralogy comprises olivine, orthopyroxene, clinopyroxene and spinel, similar to the mineralogy of the mantles of carbon-poor planets such as the Earth, and largely unaffected by the amount of carbon. Metals are either two immiscible iron-rich alloys (S-rich and S-poor) or a single iron-rich alloy in the Fe-C-S system with immiscibility depending on the S/Fe ratio and core pressure.We show that for our C-enriched compositions the minimum carbon abundance needed for C-saturation is 0.05´0.7 wt% (molar C/O " 0.002´0.03). Fully differentiated rocky exoplanets with C/O ratios more than needed for C-saturation would contain graphite as an additional layer on top of the silicate mantle. For a thick enough graphite layer, diamonds would form at the bottom of this layer due to high pressures.We model the interior structure of Kepler-37b and show that a mere 10 wt% graphite layer would decrease its derived mass by 7%, suggesting future space missions that determine both radius and mass of rocky exoplanets with insignificant gaseous envelopes could provide quantitative limits on their carbon content. Future observations of rocky exoplanets with graphite-rich surfaces would show low albedos due to the low reflectance of graphite. The absence of life-bearing elements other than carbon on the surface likely makes them uninhabitable.

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“…Prior to complete solidification, the lunar mantle overturned due to the crystallization of dense ilmeniterich cumulates above comparatively less-dense olivine and pyroxene-rich cumulates, mixing the lunar mantle (Elkins-Tanton et al, 2011;Shearer et al, 2006). Mare basalts represent partial melts derived from such cumulates and are generally separated into the low-Ti and high-Ti subgroupings, with the high-Ti basalts likely represent mixing between early-stage olivine & pyroxene-bearing cumulates and late-stage ilmenite-bearing cumulates respectively (Hess and Parmentier, 1995;van Kan Parker et al, 2011). Multiple saturation pressures of mare basalts range between 1-1.5 GPa, relating to source region depths of 200-300 km (Ding et al, 2018;Green et al, 1975;Kesson, 1975;Longhi, 1992;Longhi et al, 1972;Snyder et al, 1992;Walker et al, 1976;Walker et al, 1972).…”

Section: Resultsmentioning

confidence: 99%

The Zn, S, and Cl isotope compositions of mare basalts: Implications for the effects of eruption style and pressure on volatile element stable isotope fractionation on the Moon

Gargano

Dottin

Hopkins

et al. 2022

American Mineralogist

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We compare the stable isotope compositions of Zn, S, and Cl for Apollo mare basalts to better constrain the sources and timescales of lunar volatile loss. Mare basalts have broadly elevated yet limited ranges in δ66Zn, δ34S, and δ37ClSBC+WSC values of 1.27 ± 0.71, 0.55 ± 0.18, and 4.1 ± 4.0‰, respectively, compared to the silicate Earth at 0.15, –1.28, and 0‰, respectively. We find that the Zn, S, and Cl isotope compositions are similar between the low- and high-Ti mare basalts, providing evidence of a geochemical signature in the mare basalt source region that is inherited from lunar formation and magma ocean crystallization. The uniformity of these compositions implies mixing following mantle overturn, as well as minimal changes associated with subsequent mare magmatism. Degassing of mare magmas and lavas did not contribute to the large variations in Zn, S, and Cl isotope compositions found in some lunar materials (i.e., 15‰ in δ66Zn, 60‰ in δ34S, and 30‰ in δ37Cl). This reflects magma sources that experienced minimal volatile loss due to high confining pressures that generally exceeded their equilibrium saturation pressures. Alternatively, these data indicate effective isotopic fractionation factors were near unity. Our observations of S isotope compositions in mare basalts contrast to those for picritic glasses (Saal and Hauri 2021), which vary widely in S isotope compositions from –14.0 to 1.3‰, explained by extensive degassing of picritic magmas under high-P/PSat values (>0.9) during pyroclastic eruptions. The difference in the isotope compositions of picritic glass beads and mare basalts may result from differences in effusive (mare) and explosive (picritic) eruption styles, wherein the high-gas contents necessary for magma fragmentation would result in large effective isotopic fractionation factors during degassing of picritic magmas. Additionally, in highly vesiculated basalts, the δ34S and δ37Cl values of apatite grains are higher and more variable than the corresponding bulk-rock values. The large isotopic range in the vesiculated samples is explained by late-stage low-pressure “vacuum” degassing (P/PSat ~ 0) of mare lavas wherein vesicle formation and apatite crystallization took place post-eruption. Bulk-rock mare basalts were seemingly unaffected by vacuum degassing. Degassing of mare lavas only became important in the final stages of crystallization recorded in apatite—potentially facilitated by cracks/fractures in the crystallizing flow. We conclude that samples with wide-ranging volatile element isotope compositions are likely explained by localized processes, which do not represent the bulk Moon.

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Trace element partitioning between ilmenite, armalcolite and anhydrous silicate melt: Implications for the formation of lunar high-Ti mare basalts

Cited by 22 publications

References 59 publications

Capturing the oxidation of silicon carbide in rocky exoplanetary interiors

Capturing the oxidation of silicon carbide in rocky exoplanetary interiors

Mineralogy, Structure, and Habitability of Carbon-Enriched Rocky Exoplanets: A Laboratory Approach

The Zn, S, and Cl isotope compositions of mare basalts: Implications for the effects of eruption style and pressure on volatile element stable isotope fractionation on the Moon

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