Collisions and compositional variability in chondrule-forming events

Jacquet, Emmanuel

doi:10.1016/j.gca.2020.12.025

Cited by 24 publications

(11 citation statements)

References 107 publications

(164 reference statements)

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“…Furthermore, this can explain neither the larger thicknesses of igneous rims compared to FGRs (Matsumoto et al, 2021) nor the similar oxygen isotopic compositions of igneous rims and the host chondrules (Jacquet et al, 2015). Alternatively, microchondrules could have formed during collisions between partially molten chondrules (Dobrică & Brearley, 2016), and coarse‐grained rims could have resulted from the accretion of microchondrules near the end of crystallization (Jacquet, 2021). In this view, early accreted (and “digested”) droplets would have merely increased the size of the chondrule, perhaps accounting for the correlation between average chondrule size and igneous rim thickness (Rubin, 2010).…”

Section: Discussionmentioning

confidence: 99%

“…The FGR could have also accreted some unheated material but before it efficiently diluted the aforementioned higher temperature components. Rapid dust accretion would have been promoted by the higher dust densities estimated during chondrule formation (e.g., Alexander et al, 2008; Jacquet, 2021; Schrader et al., 2013). Chondrules may have essentially accreted all the “halo” material.…”

Section: Discussionmentioning

confidence: 99%

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Formation of chondrule fine‐grained rims from local nebular reservoirs

Pinto

Marrocchi

Jacquet

et al. 2022

Meteorit & Planetary Scien

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Chondrules are commonly surrounded by fine‐grained rims (FGRs) whose origin remains highly debated; both nebular and parent body settings are generally proposed. Deciphering their origin, however, is of fundamental importance as they could clarify the matrix–chondrule relationship and thus constrain the formation and transport conditions of chondrules in the circumsolar disk. Here, we report a systematic survey of FGRs in CO, CM, CV, and CR chondrites; we compare (i) the thickness of FGRs to the size of their host chondrules and (ii) the frequency of FGRs to the modal abundance of matrix in the respective host chondrites. Although FGRs show textural variations depending on the petrologic type of the considered chondrites, our data show a positive correlation between apparent rim thickness and the radius of the host chondrule in all chondrite groups. We also found a positive correlation between the evaluated percentages of rimmed chondrules and the modal abundance of matrix material in the chondrites. We show that this relationship could not result from parent body processes, whether matrix compaction or FGR fragmentation. Therefore, we propose that FGRs were accreted under warm conditions at the end of chondrule‐forming events. Our results thus support (i) a nebular origin for FGR, whose abundances are directly related to the abundance of available dust in regions of chondrite accretion; and (ii) the accretion of chondrites from locally formed chondrules and matrix, suggesting limited radial transport in the protoplanetary disk.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Formation of chondrule fine‐grained rims from local nebular reservoirs

Pinto

Marrocchi

Jacquet

et al. 2022

Meteorit & Planetary Scien

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“…Recent high-current X-ray maps and secondary ion mass spectrometry (SIMS) measurements of relict olivine grains have revealed that they are characterized by low refractory element (Al, Ti) contents, similar to those observed in olivine grains within AOAs (Jacquet and Marrocchi, 2017;Marrocchi et al, 2018Marrocchi et al, , 2019a. It has thus been proposed that type I chondrules are derived from AOAs or AOA-related nebular materials; these nebular condensates underwent partial melting and subsequent interactions with SiO-and Mg-rich gas (Marrocchi et al, 2018(Marrocchi et al, , 2019aVilleneuve et al, 2020;Jacquet et al, 2021;Jacquet, 2021).…”

Section: -Introductionmentioning

confidence: 96%

Conditions of chondrule formation in ordinary chondrites

Piralla

Villeneuve

Batanova

et al. 2021

Geochimica et Cosmochimica Acta

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Chondrules are sub-millimetric spheroids that are ubiquitous in chondrites and whose formation mechanism remains elusive. Textural and oxygen isotopic characteristics of chondrules in carbonaceous chondrites (CCs) suggest that they result from the recycling of isotopically heterogeneous early-condensed precursors via gas-melt interactions. Here, we report high-resolution X-ray elemental maps and in situ O isotopic analyses of FeO-poor, olivine-rich chondrules from ordinary chondrites (OCs) to compare the conditions of chondrule formation in these two main classes of chondrites. OC chondrules show minor element (e.g., Ti, Al) zonings at both the chondrule and individual olivine grain scales. Considering the entire isotopic data set, our data define a mass-independent correlation, with olivine grains showing O isotopic variations spanning more than 40 ‰. Though 16 O-rich relict olivine grains were identified in OC chondrules, they are much less abundant than in CC chondrules. They appear as two types: (i) those with low minor element abundances and ∆ 17 O < −15 ‰ and (ii) those with varying minor element abundances and less negative ∆ 17 O values averaging −5.5 ‰. The host olivine grains exhibit mass-dependent O isotopic variations within individual chondrules.Our results reveal that similar processes (precursor recycling and interactions between chondrule melts and a SiO-and Mg-rich gas) established the observed features of OC and CC chondrules. The mass-dependent isotopic variations recorded by host olivine grains result from kinetic effects induced by complex evaporation/recondensation processes during the gas-melt interactions. This suggests that OC chondrules formed through enhanced recycling processes, in good agreement with the lower abundances of relict olivine grains in OC chondrules compared to CC chondrules. We use the ∆ 18 O =  18 O −  17 O parameter to demonstrate that there is no genetic relationship between CC and OC

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“…The sticking probability f stick must be smaller than unity as a function of the collisional conditions (e.g., impact velocity, impact parameter, and size ratio) and the material properties of chondrule melts (e.g., viscosity and surface energy). The viscosity of chondrule melts sensitively depends on the temperature, and it decreases with increasing temperature (Arakawa & Nakamoto 2019;Jacquet 2021). On the other hand, the surface energy of the melts is almost constant during cooling (Arakawa & Nakamoto 2019;Jacquet 2021).…”

Section: Compound Chondrule Frequencymentioning

confidence: 99%

Cooling Rates of Chondrules after Lightning Discharge in Solid-rich Environments

Kaneko

Sato

Ikeda

et al. 2023

ApJ

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Among the several candidate models for chondrule formation, the lighting model has been recognized to be less likely than the other two major models, shock-wave heating and planetesimal collision. It might be because we have believed that the lightning model predicts cooling rates of chondrules that are too fast to reproduce their textures with the assumption that the discharge channels must be optically thin. However, the previous works revealed that the buildup of a strong electric field to generate the lightning in protoplanetary disks requires the enhancement of the solid density. Moreover, some properties of chondrules indicate their formation in environments with such a high solid density. Therefore, the discharge channels may be optically thick, and the lightning model can potentially predict the proper cooling rates of chondrules. In this study, we reinvestigate the cooling rates of chondrules produced by the lightning in the solid-rich environments considering the radiative transfer and the expansion of the hot channel. Chondrules must interact dynamically with the surrounding gas and dust via the drag force. We consider two limiting cases for the dynamics of chondrules: the drag force is ignored in the first case, and chondrules are completely coupled with their surroundings in the second case. In both cases, the lightning model predicts the proper cooling rates of chondrules under the optically thick conditions with high solid enhancement. Therefore, the lightning model is worth further investigation to judge its reliability as the source of chondrule formation.

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Collisions and compositional variability in chondrule-forming events

Cited by 24 publications

References 107 publications

Formation of chondrule fine‐grained rims from local nebular reservoirs

Formation of chondrule fine‐grained rims from local nebular reservoirs

Conditions of chondrule formation in ordinary chondrites

Cooling Rates of Chondrules after Lightning Discharge in Solid-rich Environments

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