A speciation model linking the fate of carbon and hydrogen during core – magma ocean equilibration

Gaillard, Fabrice; Malavergne, Valérie; Bouhifd, Mohamed Ali; Rogerie, Grégory

doi:10.1016/j.epsl.2021.117266

Cited by 14 publications

(6 citation statements)

References 48 publications

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“…However, we notice that all of our cases also contain H, which could form CH species (particularly at high pressure; Chi et al 2014;Li et al 2015;Gaillard et al 2022a) whose solubility could offset C saturation. Gaillard et al (2022a) suggested that above 35 GPa (corresponding to the most reducing domain of the MO), C-content at C saturation should be above 100 ppm in H-bearing silicate melts, which is largely above the C concentration in our most C-rich case. However, it is important to keep in mind that this result relies on parameterizations calibrated for much lower temperatures and pressures than those met in a deep MO.…”

Section: Graphite Saturationmentioning

confidence: 77%

“…Depending on the buoyancy of the precipitate, it could either settle at the bottom and leave the system (similar to the silicate crystals in the fractional crystallization case), remain entrained in the MO (as the silicate crystals in the equilibrium crystallization case), or accumulate at the surface and form a floating graphite layer (in which case the atmosphere redox state might be controlled by the CCO buffer; Keppler & Golabeck 2019). However, we notice that all of our cases also contain H, which could form CH species (particularly at high pressure; Chi et al 2014;Li et al 2015;Gaillard et al 2022a) whose solubility could offset C saturation. Gaillard et al (2022a) suggested that above 35 GPa (corresponding to the most reducing domain of the MO), C-content at C saturation should be above 100 ppm in H-bearing silicate melts, which is largely above the C concentration in our most C-rich case.…”

Section: Graphite Saturationmentioning

confidence: 79%

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RETRACTED: Redox Evolution of the Crystallizing Terrestrial Magma Ocean and Its Influence on the Outgassed Atmosphere

2023

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Magma oceans (MOs) are episodes of large-scale melting of the mantle of terrestrial planets. The energy delivered by the Moon-forming impact induced a deep MO on the young Earth, corresponding to the last episode of core-mantle equilibration. The crystallization of this MO led to the outgassing of volatiles initially present in the Earth’s mantle, resulting in the formation of a secondary atmosphere. During outgassing, the MO acts as a chemical buffer for the atmosphere via the oxygen fugacity, set by the equilibrium between ferrous- and ferric-iron oxides in the silicate melts. By tracking the evolution of the oxygen fugacity during MO solidification, we model the evolving composition of a C-O-H atmosphere. We use the atmospheric composition to calculate its thermal structure and radiative flux. This allows us to calculate the lifetime of the terrestrial MO. We find that, upon crystallizing, the MO evolves from a mildly reducing to a highly oxidized redox state, thereby transiting from a CO- and H2-dominated atmosphere to a CO2- and H2O-dominated one. We find the overall duration of the MO crystallization to depend mostly on the bulk H content of the mantle, and to remain below 1.5 millions yr for up to nine Earth’s water oceans’ worth of H. Our model also suggests that reduced atmospheres emit lower infrared radiation than oxidized ones, despite of the lower greenhouse effect of reduced species, resulting in a longer MO lifetime in the former case. Although developed for a deep MO on Earth, the framework applies to all terrestrial planet and exoplanet MOs, depending on their volatile budgets.

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Section: Graphite Saturationmentioning

confidence: 77%

Section: Graphite Saturationmentioning

confidence: 79%

RETRACTED: Redox Evolution of the Crystallizing Terrestrial Magma Ocean and Its Influence on the Outgassed Atmosphere

2023

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“…O 1 H − , 19 F − , 30 Si − , 31 P − , 32 S − , and 35 Cl − , they can be changed to measure other elements of interest, such as replacing the 31 P − with 14 N 16 O − and 30 Si − with 29 Si − (Gao et al, 2022), where either 30 Si or 29 Si serves as the normalized species. Considering that the partitioning behavior of any of the above-mentioned volatile elements may be affected by others (Iacono-Marziano et al, 2012;Li et al, 2015;Gaillard et al, 2022), simultaneous detection of several volatile elements is beneficial to a comprehensive evaluation of their likely interdependent partitioning behavior. The partition coefficient of volatiles between the melt and crystalline phases (e.g., bridgmanite) is affected by several factors including chemical composition, temperature, pressure, and oxygen fugacity (Litasov et al, 2003;Fu et al, 2019;Liu et al, 2021;Ishii et al, 2022b), which is still poorly constrained.…”

Section: Nanosims Analysis Of Volatile Contents In Lower Mantle Mineralsmentioning

confidence: 99%

NanoSIMS analysis of water content in bridgmanite at the micron scale: An experimental approach to probe water in Earth’s deep mantle

Yang

et al. 2023

Front. Chem.

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Water, in trace amounts, can greatly alter chemical and physical properties of mantle minerals and exert primary control on Earth’s dynamics. Quantifying how water is retained and distributed in Earth’s deep interior is essential to our understanding of Earth’s origin and evolution. While directly sampling Earth’s deep interior remains challenging, the experimental technique using laser-heated diamond anvil cell (LH-DAC) is likely the only method available to synthesize and recover analog specimens throughout Earth’s lower mantle conditions. The recovered samples, however, are typically of micron sizes and require high spatial resolution to analyze their water abundance. Here we use nano-scale secondary ion mass spectrometry (NanoSIMS) to characterize water content in bridgmanite, the most abundant mineral in Earth’s lower mantle. We have established two working standards of natural orthopyroxene that are likely suitable for calibrating water concentration in bridgmanite, i.e., A119(H2O) = 99 ± 13 μg/g (1SD) and A158(H2O) = 293 ± 23 μg/g (1SD). We find that matrix effect among orthopyroxene, olivine, and glass is less than 10%, while that between orthopyroxene and clinopyroxene can be up to 20%. Using our calibration, a bridgmanite synthesized by LH-DAC at 33 ± 1 GPa and 3,690 ± 120 K is measured to contain 1,099 ± 14 μg/g water, with partition coefficient of water between bridgmanite and silicate melt ∼0.025, providing the first measurement at such condition. Applying the unique analytical capability of NanoSIMS to minute samples recovered from LH-DAC opens a new window to probe water and other volatiles in Earth’s deep mantle.

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“…1). Since the amount of carbon species in a magma ocean is probably small and might occur at depth as CH4 instead 12 , this scenario is questionable.…”

Section: Oxygen-rich Melt In Deep Magma Oceansmentioning

confidence: 99%

Oxygen-rich melt in deep magma oceans

Gaillard

2023

Nat. Geosci.

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A speciation model linking the fate of carbon and hydrogen during core – magma ocean equilibration

Cited by 14 publications

References 48 publications

RETRACTED: Redox Evolution of the Crystallizing Terrestrial Magma Ocean and Its Influence on the Outgassed Atmosphere

RETRACTED: Redox Evolution of the Crystallizing Terrestrial Magma Ocean and Its Influence on the Outgassed Atmosphere

NanoSIMS analysis of water content in bridgmanite at the micron scale: An experimental approach to probe water in Earth’s deep mantle

Oxygen-rich melt in deep magma oceans

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