Structure of differentiated planetesimals: A chondritic fridge on top of a magma ocean

Limare, Angela; Chaussidon, M.; Kaminski, E. C.

doi:10.1016/j.icarus.2022.115100

Cited by 12 publications

(7 citation statements)

References 78 publications

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“…A magma ocean is, in general, characterized by a melt fraction of >50 %, while EC 002 probably formed from an ≈25% melting of a nearly chondritic protolith. Since temperature curves fit the U-Pb-Pb data and the melting and metamorphic temperature constraints well at one and the same depth and, in addition, are in a broad agreement with closure temperatures suggested for pyroxene and anorthite (Figure 1), our models provide a simpler and more straightforward formation scenario for EC 002 without involvement of large-scale migration or extrusion of the source melt from a deeper region into a cold crust (Sturtz et al 2022) or excavation by an impact and cooling at the surface (Barrat et al 2021). This is consistent with recent experimental studies suggesting that large-scale melt migration could have been impaired by the high viscosity of 10 2 -10 3 Pa s of andesitic melts (Collinet & Grove 2020).…”

Section: Discussionsupporting

confidence: 82%

Fitting Thermal Evolution Models to the Chronological Record of Erg Chech 002 and Modeling the Ejection Conditions of the Meteorite

Neumann,

Luther,

Trieloff

et al. 2023

Planet. Sci. J.

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The history of accretion and differentiation processes in the planetesimals is provided by various groups of meteorites. Sampling different parent body layers, they reveal the circumstances of the metal–silicate segregation and the internal structures of the protoplanets. The ungrouped achondrite Erg Chech 002 (EC 002) added to the suite of samples from primitive igneous crusts. Here we present models that utilize thermochronological data for EC 002 and fit the accretion time and size of its parent body to these data. The U-corrected Pb–Pb pyroxene, Pb–Pb phosphate, and Ar–Ar ages used imply a best-fit planetesimal with a radius of 20–30 km that formed at 0.1 Ma after calcium-aluminum-rich inclusions. Its interior melted early and differentiated by 0.5 Ma, allowing core and mantle formation with a transient lower mantle magma ocean and a melt fraction of <25% at the meteorite layering depth. EC 002 formed from this melt at a depth of 0.8 km in a partially differentiated region covered by an undifferentiated crust. By simulating collisions with impactors of different sizes and velocities, we analyzed the minimum ejection conditions of EC 002 from its original parent body and the surface composition of the impact site. The magma ocean region distinct from the layering depth of EC 002 implies that it was not involved in the EC 002 genesis. Our models estimate closure temperatures for the Al–Mg ages as 1030–1200 K. A fast parent body cooling attributes the late Ar–Ar age to a local reheating by another, late impact.

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Section: Discussionsupporting

confidence: 82%

Fitting Thermal Evolution Models to the Chronological Record of Erg Chech 002 and Modeling the Ejection Conditions of the Meteorite

Neumann,

Luther,

Trieloff

et al. 2023

Planet. Sci. J.

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“…Nevertheless, an experimental study by Faure (2020) showed that early silica crust formation (before complete differentiation) in planetesimals by metastable silica-rich liquid immiscibility or cristobalite crystallization can explain the possible origin of silica-rich chondrules. In a recent study, Sturtz et al (2022) proposed a model of planetesimal formation and evolution for the parent bodies like that of EC 002. The authors showed that a protracted and continuous accretion of primitive chondritic material over a magma ocean generated due to early accretion of the parent body can lead to the preservation of a few kilometer thick chondritic crust.…”

Section: Discussionmentioning

confidence: 99%

“…In a recent study, Sturtz et al. (2022) proposed a model of planetesimal formation and evolution for the parent bodies like that of EC 002. The authors showed that a protracted and continuous accretion of primitive chondritic material over a magma ocean generated due to early accretion of the parent body can lead to the preservation of a few kilometer thick chondritic crust.…”

Section: Discussionmentioning

confidence: 99%

⁵³Mn‐⁵³Cr chronology and ε⁵⁴Cr‐Δ¹⁷O genealogy of Erg Chech 002: The oldest andesite in the solar system

Anand

Mezger

2022

Meteorit & Planetary Scien

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The meteorite Erg Chech (EC) 002 is the oldest felsic igneous rock from the solar system analyzed to date and provides a unique opportunity to study the formation of felsic crusts on differentiated protoplanets immediately after metal–silicate equilibration or core formation. The extinct 53Mn‐53Cr chronometer provides chronological constraints on the formation of EC 002 by applying the isochron approach using chromite, metal–silicate–sulfide, and whole‐rock fractions as well as “leachates” obtained by sequential digestion of a bulk sample. Assuming a chondritic evolution of its parent body, a 53Cr/52Cr model age is also obtained from the chromite fraction. The 53Mn‐53Cr isochron age of 1.73 ± 0.96 Ma (anchored to D'Orbigny angrite) and the chromite model age constrained between 1.46−0.68+0.78 and 2.18−1.06+1.32 Ma after the formation of calcium‐aluminium‐rich inclusions (CAIs) agree with the 26Al‐26Mg ages (anchored to CAIs) reported in previous studies. This indicates rapid cooling of EC 002 that allowed near‐contemporaneous closure of multiple isotope systems. Additionally, excess in the neutron‐rich 54Cr (nucleosynthetic anomalies) combined with mass‐independent isotope variations of 17O provides genealogical constraints on the accretion region of the EC 002 parent body. The 54Cr and 17O isotope compositions of EC 002 confirm its origin in the “noncarbonaceous” reservoir and overlap with the vestoid material Northwest Africa 12217 and anomalous eucrite Elephant Moraine 92023. This indicates a common feeding zone during accretion in the protoplanetary disk between the source of EC 002 and vestoids. The enigmatic origin of iron meteorites remains still unresolved as EC 002, which is more like a differentiated crust, has an isotope composition that does not match known iron meteorite groups that were once planetesimal cores.

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“…For undifferentiated CM-chondrite-like planetesimals, depending on whether there is an existing atmosphere or gaseous envelope around them as they are accreting can influence whether they are capable of retaining their degassed volatiles or if those species escape permanently. In addition to the pressure and temperature gradients inside the planetesimal (Sturtz et al 2022), our study demonstrates that the total surface pressure and redox conditions influence the evaporation rate of materials (Equation ( 2)) and likely impact the temperatures at which certain elements degas. For example, for the samples of Murchison heated under atmospheric pressure and more oxidizing conditions compared to the vacuum experiments, sulfur degassed both at 800 • C and 1000 • C, while zinc did not experience any detectable outgassing over the entire temperature range.…”

Section: Volatile Depletion Of Planetesimalsmentioning

confidence: 86%

Outgassing Composition of the Murchison Meteorite: Implications for Volatile Depletion of Planetesimals and Interior-atmosphere Connections for Terrestrial Exoplanets

Thompson,

Telus,

Edwards

et al. 2023

Planet. Sci. J.

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Outgassing is a central process during the formation and evolution of terrestrial planets and their atmospheres both within and beyond the solar system. Although terrestrial planets’ early atmospheres likely form via outgassing during planetary accretion, the connection between a planet’s bulk composition and its initial atmospheric properties is not well understood. One way to inform this connection is to analyze the outgassing compositions of meteorites, and in particular carbonaceous chondrites, because they are some of the most volatile-rich, primitive materials (in terms of their bulk compositions) that are available for direct study. In addition, they may serve as compositional analogs for the building block materials of terrestrial planets in our solar system and around other Sun-like stars. This study builds upon previous outgassing experiments that monitored the abundances of volatile species (e.g., H2O, CO, and CO2) released from the Murchison meteorite. To gain a more complete understanding of Murchison’s outgassing composition, we perform a series of heating experiments under atmospheric pressure (1 bar) and vacuum (∼10−9 bar) conditions on samples of the Murchison meteorite and subsequent bulk element analysis to inform the outgassing trends of a suite of major elements in Murchison (e.g., Fe, Mg, Zn, and S). Under both pressure conditions, sulfur outgases significantly at the highest temperatures (∼800°C–1000 °C). For the samples heated under vacuum conditions, we also detect outgassing of zinc. Combined with prior outgassing experiments, this study provides important insights into the volatile depletion patterns of undifferentiated planetesimals and the early outgassing compositions of terrestrial exoplanets.

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Structure of differentiated planetesimals: A chondritic fridge on top of a magma ocean

Cited by 12 publications

References 78 publications

Fitting Thermal Evolution Models to the Chronological Record of Erg Chech 002 and Modeling the Ejection Conditions of the Meteorite

Fitting Thermal Evolution Models to the Chronological Record of Erg Chech 002 and Modeling the Ejection Conditions of the Meteorite

⁵³Mn‐⁵³Cr chronology and ε⁵⁴Cr‐Δ¹⁷O genealogy of Erg Chech 002: The oldest andesite in the solar system

Outgassing Composition of the Murchison Meteorite: Implications for Volatile Depletion of Planetesimals and Interior-atmosphere Connections for Terrestrial Exoplanets

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Structure of differentiated planetesimals: A chondritic fridge on top of a magma ocean

Cited by 12 publications

References 78 publications

Fitting Thermal Evolution Models to the Chronological Record of Erg Chech 002 and Modeling the Ejection Conditions of the Meteorite

Fitting Thermal Evolution Models to the Chronological Record of Erg Chech 002 and Modeling the Ejection Conditions of the Meteorite

53Mn‐53Cr chronology and ε54Cr‐Δ17O genealogy of Erg Chech 002: The oldest andesite in the solar system

Outgassing Composition of the Murchison Meteorite: Implications for Volatile Depletion of Planetesimals and Interior-atmosphere Connections for Terrestrial Exoplanets

Contact Info

Product

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⁵³Mn‐⁵³Cr chronology and ε⁵⁴Cr‐Δ¹⁷O genealogy of Erg Chech 002: The oldest andesite in the solar system