Chondrules as direct thermochemical sensors of solar protoplanetary disk gas

Libourel, G.; Portail, Marc

doi:10.1126/sciadv.aar3321

Cited by 63 publications

(67 citation statements)

References 46 publications

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“…3, Table S1). Such oscillatory zonings have previously been reported from cathodoluminescence maps (Steele et al, 1985;Steele, 1986Steele, , 1995Libourel and Portail, 2018) and phosphorus X-ray maps (McCanta et al, 2016), and one Allan Hills A81189 (EH3) chondrule even showed strong Fo 75-97 oscillations in its olivine phenocrysts (Lusby et al, 1987).…”

Section: Resultssupporting

confidence: 73%

“…In this model, relict grains are thus direct proxies of the first solids formed in the SPD, whereas host chondrule crystals represent thermochemical and isotopic sensors of the surrounding gas during chondrule formation. At the same time, (Libourel and Portail, 2018) interpreted type I chondrule cathodoluminescence zoning patterns similar to ours in X-ray maps as the result of crystallization from Ca-Alrich melts produced in dense environments of the SPD. Clearly, the study of such zonings is nascent and will provide valuable insights into chondrule formation.…”

Section: Introductionsupporting

confidence: 76%

“…1 and 2; see also Jacquet and Marrocchi, 2017). Outer-chondrule olivine crystals (termed ''palisadic" by Libourel and Portail, 2018) have the maximum Ca, Al, and Ti contents of the chondrule in their interiors, but those contents decrease as Mn content increases toward the crystal edge. Whereas the Ca and Mn zonings are smooth (decreasing from 0.5 to 0.15 wt% and increasing from 0.03 to 0.9 wt%, respectively, from core to rim), Ti and Al zonings are oscillatory (possibly in a more pro-nounced way for Ti) with periods of 5-20 mm, ranging from 200-1500 ppm Ti and 250-4000 ppm Al (Fig.…”

Section: Resultsmentioning

confidence: 99%

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Formation of CV chondrules by recycling of amoeboid olivine aggregate-like precursors

Marrocchi

Euverte

Villeneuve

et al. 2019

Geochimica et Cosmochimica Acta

102

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We have studied porphyritic olivine-rich chondrules of the carbonaceous chondrite Kaba (CV3) by combined highresolution X-ray mapping, quantitative electron microprobe analyses, and oxygen isotopic analyses via secondary ion mass spectrometry. These chondrules contain smaller inner-chondrule olivine grains characterized by low refractory element (Ca, Al, Ti) contents, and larger outer-chondrule olivine crystals that are enriched in refractory elements and show complex Ti and Al oscillatory zonings. Our O isotopic survey revealed that many of the inner-chondrule olivines are 16 O-richer than the relatively isotopically uniform outer-chondrule olivines. Inner-chondrule olivine crystals-only a minority of which may be derived from earlier generations of chondrules-are likely mostly inherited from nebular condensates similar to AOAs, as they share similar isotopic and chemical features and are thus interpreted as relict grains. Still, being 16 O-poorer than most AOAs, they may have experienced significant exchange with a 16 O-poor reservoir prior to chondrule formation (even if to a lesser degree than relicts in CM2 and ungrouped C2 chondrites). Subsequent incomplete melting of the relict grains produced Ca-Al-Ti-rich melts that engulfed the remaining relict olivine grains. The complex Ti and Al zoning patterns in outer chondrule (host) olivines, in particular the systematic dilution near the margin, seem to reflect gas-melt interactions (with e.g. SiO (g), Mg (g)) which also buffered the O isotopic composition of chondrule hosts. Together, these results demonstrate that important episodes of recycling of nebular condensates occurred in the solar protoplanetary disk.

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Section: Resultssupporting

confidence: 73%

Section: Introductionsupporting

confidence: 76%

Section: Resultsmentioning

confidence: 99%

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Formation of CV chondrules by recycling of amoeboid olivine aggregate-like precursors

Marrocchi

Euverte

Villeneuve

et al. 2019

Geochimica et Cosmochimica Acta

102

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“…The absence of metal grains in completely molten chondrule precursors was theoretically predicted by Uesugi et al (2005Uesugi et al ( , 2008. In addition, the unique occurrence of metal grains in the core region of magnesium-rich olivine crystals of porphyritic chondrules suggests that the metal grains act as seeding agents during the crystal growth of the olivine crystals in porphyritic chondrules (Libourel & Portail 2018), and the difference in the textures of porphyritic or barred olivine chondrules is linked to the presence/absence of iron-nickel metal grains.…”

Section: Metal Grainsmentioning

confidence: 87%

Compound Chondrule Formation in Optically Thin Shock Waves

Arakawa

Nakamoto

2019

ApJ

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Shock-wave heating within the solar nebula is one of the leading candidates for the source of chondruleforming events. Here, we examine the possibility of compound chondrule formation via optically thin shock waves. Several features of compound chondrules indicate that compound chondrules are formed via the collisions of supercooled precursors. We evaluate whether compound chondrules can be formed via the collision of supercooled chondrule precursors in the framework of the shock-wave heating model by using semi-analytical methods and discuss whether most of the crystallized chondrules can avoid destruction upon collision in the post-shock region. We find that chondrule precursors immediately turn into supercooled droplets when the shock waves are optically thin and they can maintain supercooling until the condensation of evaporated fine dust grains. Owing to the large viscosity of supercooled melts, supercooled chondrule precursors can survive high-speed collisions on the order of 1 km s −1 when the temperature is below ∼ 1400 K. From the perspective of the survivability of crystallized chondrules, shock waves with a spatial scale of ∼ 10 4 km may be potent candidates for the chondrule formation mechanism. Based on our results from one-dimensional calculations, a fraction of compound chondrules can be reproduced when the chondrule-to-gas mass ratio in the pre-shock region is ∼ 2 × 10 −3 , which is approximately half of the solar metallicity.

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“…Such accretion mechanisms are of specific interest as they may have played an important role in terrestrial planet formation (e.g., Bollard et al, ; Cuzzi et al, ; Jacobsen & Walsh, ; Johansen et al, ; Levison et al, ), since chondrule‐rich accretion can potentially explain volatile and moderately volatile element abundances in the BSE and BE (e.g., Amsellem et al, ; Hewins & Herzberg, ; Mahan, Siebert, et al, ; Righter et al, ), especially in the absence of appreciable volatile loss from Earth and other terrestrial bodies during accretion (e.g., Canup et al, ; Stewart et al, ). Moreover, chondrules likely provide a reliable record of the conditional and compositional evolution of the solar system during the planet‐forming epoch (Libourel & Portail, ; Mahan, Moynier, et al, ). In the following models, both the size and volatile contents of Earth's accreting materials increase with time, culminating in a relatively volatile‐rich, large impactor corresponding to 9.5% M E toward the end of accretion.…”

Section: Discussionmentioning

confidence: 99%

Investigating Earth's Formation History Through Copper and Sulfur Metal‐Silicate Partitioning During Core‐Mantle Differentiation

et al. 2018

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Identifying extant materials that act as compositional proxies for Earth is key to understanding its accretion. Copper and sulfur are both moderately volatile elements; however, they display different geochemical behavior (e.g., phase affinities). Thus, individually and together, these elements provide constraints on the source material and conditions of Earth's accretion, as well as on the timing and evolution of volatile delivery to Earth. Here we present laser‐heated diamond anvil cell experiments at pressures up to 81 GPa and temperatures up to 4,100 K aimed at characterizing Cu metal‐silicate partitioning at conditions relevant to core‐mantle differentiation in Earth. Partitioning results have been combined with literature results for S in Earth formation modeling to constrain accretion scenarios that can arrive at present‐day mantle Cu and S contents. These modeling results indicate that the distribution of Cu and S in Earth may be the result of accretion largely from material(s) with Cu contents at or above chondritic values and S contents that are strongly depleted, such as that in bulk CH chondrites, and that the majority of Earth's mass (~3/4) accreted incrementally via pebble and/or planetesimal accretion.

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Chondrules as direct thermochemical sensors of solar protoplanetary disk gas

Abstract: Cathodoluminescence reveals structures indicative of gas-assisted epitaxial growth during chondrule melt crystallization.

Cited by 63 publications

References 46 publications

Formation of CV chondrules by recycling of amoeboid olivine aggregate-like precursors

Formation of CV chondrules by recycling of amoeboid olivine aggregate-like precursors

Compound Chondrule Formation in Optically Thin Shock Waves

Investigating Earth's Formation History Through Copper and Sulfur Metal‐Silicate Partitioning During Core‐Mantle Differentiation

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