Solubility of Rock in Steam Atmospheres of Planets

Fegley, B.; Jacobson, Nathan; Williams, Krystle; Plane, J. M. C.; Schaefer, Laura; Lodders, K.

doi:10.3847/0004-637x/824/2/103

Cited by 51 publications

(70 citation statements)

References 159 publications

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“…We suggest the auxiliary/complementary use of observations obtained from the permanent magma ocean type, such as potentially on 55 Cancri e (Demory et al 2016;Angelo & Hu 2017) and Kepler 78b. From there one could isolate characteristic atmospheric signatures such as: the atmospheric effects of evaporated silicate species that develop over the molten rocky surface (Fegley et al 2016;Kite et al 2016;Hammond & Pierrehumbert 2017) and the oxides in the presence of a steam atmosphere (Fegley et al 2016). Detecting similar silicate cloud signatures on planets close to the continuous MO compositional distinction that is observed at low vapor pressures (4 bar) would serve as a proxy of their composition (T RF,0 ) and of their water content.…”

Section: Magma Oceans On Other Planetsmentioning

confidence: 99%

What Factors Affect the Duration and Outgassing of the Terrestrial Magma Ocean?

Nikolaou

Katyal

Tosi

et al. 2019

ApJ

141

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The magma ocean (MO) is a crucial stage in the build-up of terrestrial planets. Its solidification and the accompanying outgassing of volatiles set the conditions for important processes occurring later or even simultaneously, such as solid-state mantle convection and atmospheric escape. To constrain the duration of a global-scale Earth MO we have built and applied a 1D interior model coupled alternatively with a grey H 2 O/CO 2 atmosphere or with a pure H 2 O atmosphere treated with a line-by-line model described in a companion paper by Katyal et al. (2019). We study in detail the effects of several factors affecting the MO lifetime, such as the initial abundance of H 2 O and CO 2 , the convection regime, the viscosity, the mantle melting temperature, and the longwave radiation absorption from the atmosphere. In this specifically multi-variable system we assess the impact of each factor with respect to a reference setting commonly assumed in the literature. We find that the MO stage can last from a few thousand to several million years. By coupling the interior model with the line-by-line atmosphere model, we identify the conditions that determine whether the planet experiences a transient magma ocean or it ceases to cool and maintains a continuous magma ocean. We find a dependence of this distinction simultaneously on the mass of the outgassed H 2 O atmosphere and on the MO surface melting temperature. We discuss their combined impact on the MO's lifetime in addition to the known dependence on albedo, orbital distance and stellar luminosity and we note observational degeneracies that arise thereby for target exoplanets.

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Section: Magma Oceans On Other Planetsmentioning

confidence: 99%

What Factors Affect the Duration and Outgassing of the Terrestrial Magma Ocean?

Nikolaou

Katyal

Tosi

et al. 2019

ApJ

141

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“…Some other elements are sensitive to the presence of volatiles, such as S, that stabilise GeS(g) and SnS(g) in the solar nebula, but, during evaporation of sulfur-free basaltic magma, are constrained to form oxides (see section 3.0. for a discussion). It is emphasised that this behaviour is relevant to volatile-poor systems that lack major gas species found in many terrestrial (and extra-terrestrial) magmatic systems, notably H2O, SO2, CO2, CO, CH4, H2S, in addition to halides such as Cl and F. These compounds can preferentially complex metallic elements, thereby stabilising them in the gas phase relative to the nominally 'dry' case (Symonds and Reed 1993;Matousek 1998;Meschter et al 2013;Fegley et al 2016;Renggli et al 2017). Although these volatiles are readily degassed or lost during high temperature vaporisation processes, such that they may be nearly absent at the temperatures sufficient to vaporise metallic elements, they were also probably extant on primordial planetary atmospheres (section 3.0.).…”

Section: Other Trace Elementsmentioning

confidence: 99%

“…The tabulated thermodynamic data for gaseous Cu and CuCl (e.g., JANAF or IVTAN) show Keq for the Cu -CuCl reaction decreases (i.e., the ΔG° of reaction is less negative) with increasing temperature; hence at otherwise constant conditions Cu is favoured at higher temperature. Figure 12 shows the pressure dependence of the CuCl/Cu ratio at 2000 K for the BSEsteam atmosphere model of Fegley et al (2016). This model uses a CuO0.5 activity coefficient of 3.5 based on Wood and Wade (2013) and Holzheid and Lodders (2001); Fegley et al (2016) describe other details of the calculations, which consider chemical equilibrium in the magma, between gas and magma, and in the gas phase.…”

Section: Cu-bearing Gasesmentioning

confidence: 99%

Thermodynamics of Element Volatility and its Application to Planetary Processes

Sossi

Fegley

2018

Reviews in Mineralogy and Geochemistry

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3) Evaporation on small planetary bodies (section 4.0.) 4) Evaporation during giant impacts (section 4.0.)To constrain the conditions under which these processes occur necessitates thermodynamic data of gaseous-and condensed species. Therefore, a review of our knowledge and lack thereof, is also presented (section 2.0.). Much of our information on thermodynamic quantities of gaseous species comes from spectrometric measurements, undertaken from the 1950s onwards, largely on simple (binary and ternary) systems (e.g., see Brewer 1953;Margrave 1967;Lamoreaux et al. 1987, and section 2.0.). This information is now readily available in compilations of thermodynamic data such as JANAF (Chase 1998) or IVTAN (Glushko et al. 1999). However, the application of these data to more complex, natural geological systems is less straightforward.Instead, for lack of any other comprehensive volatility scale, 50% nebular condensation temperatures, Tc, (Grossman and Larimer 1974;Lodders 2003), which describe the temperature at which half of the abundance of an element is condensed in the solar nebula, are frequently used to discuss elemental volatility in planetary environments. However, these Tc are strictly relevant only at the pressure and temperature conditions of a solar-composition protoplanetary accretion disk (e.g., the solar nebula). Namely, at low total pressures (PT ≲10 -2 bar), solar or close to solar metallicity 2 (i.e., PT ~ PH2 + PH + PHe), oxygen fugacities ~ 6 log bar units below the Iron -Wüstite (IW) buffer (due to the low H2O/H2 ratios, 5 × 10 -4 ; Rubin et al. 1988;Grossman et al., 2008). Boss (1998) and Woolum and Cassen (1999), to give two examples, used astronomical observations to model midplane temperatures in protoplanetary accretion disks in the planet-forming region and found temperatures <1600 K.Petrological observations of Calcium, Al-rich inclusions (CAI) with the highly fractionated group II rare-earth element (REE) pattern 3 (Boynton 1975) indicate they formed by fractional condensation (Boynton 1975;Davis and Grossman 1979) at temperatures between 1676 K, 1463 K, 1296 K at total pressures (PT) of 10 -3 bar, 10 -6 bar, and 10 -9 bar, respectively (Kornacki and Fegley 1986). At total pressures above ≈10 -2 bar, liquids condense in place of solids (Ebel, 2004) and departures from solar composition (e.g., by changes in metallicity or H-loss on a planetary body) lead to condensation temperatures different to those in a solar-composition system (Larimer and Bartholomay 1979; Lodders and Fegley 1999; Schaefer and Fegley 2010). Thus, the complexity of evaporation and condensation reactions are such that, at conditions outside this range, the relevant gas species, their equilibrium partial pressures and mechanisms driving their escape diverge greatly. Potentially powerful tracers of the conditions under which these gas-liquid/solid processes occur are the moderately volatile elements (MVEs), defined as those that condense from a solar composition nebular condensation and evaporation of silicates under post-n...

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“…Processes depleting MVEs during planetesimal/planet formation include: 4) accretional volatile loss (Ringwood, 1966;Albarède, 2009;Hin et al, 2017); 5) giant impacts (Paniello et al, 2012;Wang and Jacobsen, 2016b); 6) magma ocean degassing (Day and Moynier, 2014;Kato et al, 2015); 7) extraction into steam atmospheres and atmospheric loss (Fegley et al, 2016;Young et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Potassium isotope compositions of carbonaceous and ordinary chondrites: Implications on the origin of volatile depletion in the early solar system

Bloom¹,

Lodders²,

Chen³

et al. 2020

Geochimica et Cosmochimica Acta

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2020) Potassium isotope compositions of carbonaceous and ordinary chondrites: Implications on the origin of volatile depletion in the early solar system. Geochimica et Cosmochimica Acta, in press. ABSTRACT Among solar system materials there are variable degrees of depletion in moderately volatile elements (MVEs, such as Na, K, Rb, Cu, and Zn) relative to the proto-solar composition. Whether these depletions are due to nebular and/or parent-body (asteroidal or planetary) processes is still under debate. In order to help decipher the MVE abundances in early solar system materials, we conducted a systematic study of highprecision K stable isotopic compositions of a suite of whole-rock samples of wellcharacterized carbonaceous and ordinary chondrites. We analyzed 16 carbonaceous chondrites (CM1-2, CO3, CV3, CR2, CK4-5 and CH3) and 28 ordinary chondrites covering petrological types 3 to 6 and chemical groups H, L, and LL. We observed significant K isotope (δ 41 K) variations (−1.54 to 0.70 ‰) among the carbonaceous and ordinary chondrites. In general, the two major chondrite groups are distinct: The K isotope compositions of carbonaceous chondrites are largely higher than the Bulk Silicate Earth (BSE) value, whereas ordinary chondrites show K isotope compositions that are typically lower than the BSE value. Neither carbonaceous nor ordinary chondrites show clear/resolvable correlations between K isotopes and chemical groups, petrological types, shock levels, cosmic-ray exposure ages, fall/find occurrence, or terrestrial weathering. Importantly, the lack of a clear trend between K isotopes and K content among chondrites indicates that the K isotope fractionations were decoupled from the relative elemental K depletions, which is inconsistent with a single-stage partial vaporization or condensation process to account for these MVE depletion patterns among chondrites. The range of K isotope variations in the carbonaceous chondrites in this study is consistent with a fourcomponent (chondrule, refractory inclusion, matrix and water) mixing model that is able to explain the bulk elemental and isotopic compositions of the main carbonaceous chondrite groups, but requires a fractionation in K isotopic compositions in chondrules.We propose that the major control of the isotopic compositions of group averages is condensation and/or vaporization in pre-accretional (nebular) environments that is preserved in the compositional variation of chondrules. Parent-body processes, such as aqueous alteration, thermal metamorphism, and metasomatism, can mobilize K and affect the K isotopes in individual samples. In the case of the ordinary chondrites, the full range of K isotopic variations can only be explained by the combined effects of the size and relative abundances of chondrules, parent-body aqueous and thermal alteration, and possible sampling bias.compositions between different planetary materials (e.g., Earth and Moon) that were subsequently used to better understand the accretion mechanism of different planetary bodies.

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Solubility of Rock in Steam Atmospheres of Planets

Cited by 51 publications

References 159 publications

What Factors Affect the Duration and Outgassing of the Terrestrial Magma Ocean?

What Factors Affect the Duration and Outgassing of the Terrestrial Magma Ocean?

Thermodynamics of Element Volatility and its Application to Planetary Processes

Potassium isotope compositions of carbonaceous and ordinary chondrites: Implications on the origin of volatile depletion in the early solar system

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