Mixing and Transport of Dust in the Early Solar Nebula as Inferred from Titanium Isotope Variations among Chondrules

Gerber, Simone; Burkhardt, C.; Budde, G.; Metzler, K.; Kleine, T.

doi:10.3847/2041-8213/aa72a2

Cited by 84 publications

(118 citation statements)

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“…The Ti isotope anomalies in the CC chondrules are correlated with their Ti concentration and size, while no such relation is observed in OC and EC chondrules. This was interpreted as evidence for the presence and heterogeneous distribution of CAI-like material among chondrule precursors in the formation region of carbonaceous chondrites (Gerber et al 2017). These observations indicate that bulk carbonaceous chondrites do not only contain CAIs sensu stricto, but also reprocessed CAI-like material.…”

Section: Titanium Isotope Anomalies In Meteoritic Materialsmentioning

confidence: 96%

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Elemental and isotopic variability in solar system materials by mixing and processing of primordial disk reservoirs

Burkhardt

Dauphas

Hans

et al. 2019

Geochimica et Cosmochimica Acta

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Isotope anomalies among planetary bodies provide key constraints on planetary genetics and the Solar System's dynamical evolution. However, to unlock the full potential of these anomalies for constraining the processing, mixing, and transport of material in the disk it is essential to identify the main components responsible for producing planetary-scale isotope variations, and to investigate how they relate to the isotopic heterogeneity inherited from the Solar System's parental molecular cloud. To address these issues we measured the Ti and Sr isotopic compositions of Ca,Al-rich inclusions (CAIs) from the Allende CV3 chondrite, as well as acid leachates and an insoluble residue from the Murchison CM2 chondrite, and combine these results with literature data for presolar grains, hibonites, chondrules, and bulk meteorites. Our analysis reveals that the internal mineral-scale nebular isotopic heterogeneity as sampled by leachates and presolar grains is largely decoupled from the planetary-scale isotope anomalies as sampled by bulk meteorites. We show that variable admixing of CAIlike refractory material to an average inner solar nebula component can explain the planetaryscale Ti and Sr isotope anomalies and the elemental and isotopic difference between noncarbonaceous (NC) and carbonaceous (CC) nebular reservoirs for these elements.Combining isotope anomaly data for a large number of elements (Ti, Sr, Ca, Cr, Ni, Zr, Mo, Ru, Ba, Nd, Sm, Hf, W, and Os) reveals that the offset of the CC from the NC reservoir towards the composition of CAIs is a general trend and not limited to refractory elements. This implies that the CC reservoir is the product of mixing between NC material and a reservoir (called IC for Inclusion-like Chondritic component) whose isotopic composition is similar to that of CAIs, but whose chemical composition is similar to bulk chondrites. In our preferred model, the distinct isotopic compositions of these two nebular reservoirs reflect an inherited heterogeneity of the solar system's parental molecular cloud core, which therefore has never been fully homogenized during collapse. Planetary-scale isotopic anomalies are thus caused by variable mixing of isotopically distinct primordial disk reservoirs, the selective processing of these reservoirs in different nebular environments, and the heterogeneous distribution of the thereby forming nebular products.

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Section: Titanium Isotope Anomalies In Meteoritic Materialsmentioning

confidence: 96%

“…Chondrules from carbonaceous, ordinary, and enstatite chondrites (Gerber et al 2017), together with chondrite matrix, bulk meteorites, and CAIs (Trinquier et al 2009;Zhang et al 2011) plot along a single ε 46 Ti-ε 50 Ti correlation line ( Fig. 6b).…”

Section: Titanium Isotope Anomalies In Meteoritic Materialsmentioning

confidence: 99%

Elemental and isotopic variability in solar system materials by mixing and processing of primordial disk reservoirs

Burkhardt

Dauphas

Hans

et al. 2019

Geochimica et Cosmochimica Acta

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“…Indeed these CAIs are characterized by nucleosynthetic stable isotopic anomalies (e.g. in Ti, Ca; MacPherson 2014; Kööp et al 2018) much in excess of those seen in bulk chondrules (Gerber et al 2017) or meteorites (Trinquier et al 2009). This suggests they formed early, perhaps during infall of an isotopically heterogeneous protosolar cloud, before turbulent mixing essentially suppressed the heterogeneities (e.g.…”

Section: 2mentioning

confidence: 99%

Beryllium-10 production in gaseous protoplanetary disks and implications for the astrophysical setting of refractory inclusions

Jacquet

2019

A&A

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Calcium-Aluminum-rich Inclusions (CAIs), the oldest known solids of the solar system, show evidence for the past presence of shortlived radionuclide beryllium-10, which was likely produced by spallation during protosolar flares. While such 10 Be production has hitherto been modeled at the inner edge of the protoplanetary disk, I calculate here that spallation at the disk surface may reproduce the measured 10 Be/ 9 Be ratios at larger heliocentric distances. Beryllium-10 production in the gas prior to CAI formation would dominate that in the solid. Interestingly, provided the Sun's proton to X-ray output ratio does not decrease strongly, 10 Be/ 9 Be at the CAI condensation front would increase with time, explaining the reduced values in a (presumably early) generation of CAIs with nucleosynthetic anomalies. CAIs thus need not have formed very close to the Sun and may have condensed at 0.1-1 AU where sufficiently high temperatures originally prevailed.

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“…There are however few such data on individual chondrules. Gerber et al (2017) found that the Ti isotope compositions of those chondrules were fairly uniform, around the terrestrial value, distinct from that of the (equally uniform) ordinary chondrite chondrules. This contrasts with the range exhibited in single carbonaceous chondrites, attributed by them to variable admixtures in their precursors of CAI-like material, presumably lacking in the enstatite chondrite reservoir.…”

Section: Isotopic Compositionmentioning

confidence: 84%

Chondrules in Enstatite Chondrites

Jacquet¹,

Piani²,

Weisberg³

Chondrules

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We review silicate chondrules and metal-sulfide nodules in unequilibrated enstatite chondrites (EH3 and EL3). Their unique mineralogical assemblage, with a wide diversity of opaque phases, nitrides, nearly FeO-free enstatite etc. testify to exceptionally reduced conditions. While those have long been ascribed to a condensation sequence at supersolar C/O ratios, with the oldhamite-rich nodules among the earliest condensates, evidence for relatively oxidized local precursors suggests that their peculiarities may have been acquired during the chondrule-forming process itself. Silicate phases may have been then sulfidized in an O-poor and S-rich environment; metal-sulfide nodules in EH3 chondrites could have originated in the silicate chondrules whereas those in EL3 may be impact products. The astrophysical setting (nebular or planetary) where such conditions were achieved, whether by depletion in water or enrichment in dry organics-silicate mixtures, is uncertain, but was most likely sited inside the snow line, consistent with the Earth-like oxygen isotopic signature of most EC silicates, with little data constraining its epoch yet. 2012), suggesting relatively similar geneses. Their isotopic signature is closest to that of the Earth and the Moon than any other chondrite group, suggesting that they represent material from the inner Solar System and not some aberrant exotic reservoir. As further evidence that they are not mere curiosities, enstatite chondrites represent at least two independent chemical groups (EH and EL, with the former more metal-rich and reduced than the latter) plus several anomalous samples presumably from yet other parent bodies (Weisberg & Kimura 2012).The reason for the unusually reduced character of enstatite chondrite chondrules is not known. It may actually pertain not only to silicate chondrules, but also to the opaque (metal-sulfide) nodules common in EC which it is a matter of language convenience to also call chondrules or not depending on their genetic links to the former. A difficulty in the study of unequilibrated EC (Weisberg & Kimura 2012) is their rarity, especially for observed falls (only three known, Qingzhen, Parsa and Galim, all EH3s), whereas finds are prone to the easy weathering of their reduced mineralogy. Yet substantial progress has been accomplished in the past decade on EC chondrules, from the isotopic, chemical and mineralogical point of view, with new insights on their astrophysical context of formation, and warrants a review of the field. In this chapter, we will describe the petrographic, chemical and isotopic characteristics of chondrules, including opaque nodules. We will then discuss competing models for their reduced parageneses, in particular formation in a reduced condensation sequence or reduction of material during chondrule melting. We finally discuss the astrophysical setting that may have brought about the fractionations inferred for such environments, and its possible spatiotemporal location in the early Solar System. Figure 2: (a) MSNs in the EH3 cho...

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Mixing and Transport of Dust in the Early Solar Nebula as Inferred from Titanium Isotope Variations among Chondrules

Cited by 84 publications

References 45 publications

Elemental and isotopic variability in solar system materials by mixing and processing of primordial disk reservoirs

Elemental and isotopic variability in solar system materials by mixing and processing of primordial disk reservoirs

Beryllium-10 production in gaseous protoplanetary disks and implications for the astrophysical setting of refractory inclusions

Chondrules in Enstatite Chondrites

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