Chondrules: Ubiquitous Chondritic Solids Tracking the Evolution of the Solar Protoplanetary Disk

Bizzarro, Martin; Connelly, James N.; Krot, Alexander N.

doi:10.1007/978-3-319-60609-5_6

Cited by 18 publications

(11 citation statements)

References 125 publications

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“…This suggests that chondrules may form the building blocks for the UPB, which is consistent with the chondrule accretion model indicating chondrules may represent the pebbles at the origin of the building blocks for the terrestrial planets (Johansen et al 2015). However, this age of CO chondrule precursors is older than some of the last melting ages for individual chondrules (dated by U-corrected Pb-Pb chronometry; e.g., OC, CV, and CR chondrules) that can span up to 4 Ma after CAI (Connelly et al 2012;Bizzarro et al 2017;Bollard et al 2017). This observation can be reconciled considering that chondrule precursors rather than chondrules may represent the building blocks for the planetesimals (Johansen et al 2015), which can be supported by the ε 54 Cr for chondrules in OCs, down to −0.87±0.09 (Bollard et al 2019).…”

Section: Timescale Of Upb's Evolutionsupporting

confidence: 82%

Chromium Isotopic Constraints on the Origin of the Ureilite Parent Body

Zhu

Moynier

Schiller

et al. 2020

ApJ

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We report on the mass-independent Cr isotope compositions of 11 main group ureilites and an ureilitic trachyandesite (ALM-A). The 54 Cr/ 52 Cr ratios for main group ureilites vary from −1.06±0.04 to −0.78±0.05 and averaged at −0.91±0.15 (2SD, N=18) including the data from literature. We argue that this variation reflects primitive mantle heterogeneities within the ureilite parent body (UPB). As such, this body did not experience a global-scale magma ocean, which is consistent with heterogeneous O isotope in ureilites. Furthermore, the ε 54 Cr values, Mn/Cr ratios, C isotope ratios, Mg#values, and Fe/Mn ratios in the olivine cores of ureilites are correlated with each other, which suggests the mixing of ureilite precursors from at least two reservoirs, rather than a smelting process or the oxidation from ice melting. All the ureilite samples (including the ALM-A) fall on a well-defined 53 Mn-53 Cr isochron corresponding to a 53 Mn/ 55 Mn ratio of (6.02 ± 1.59)×10 −6 , which translates to an age of 4566.7±1.5 Ma (within 2 Ma after calcium-aluminum-rich inclusions; CAIs) when anchored to the U-corrected Pb-Pb age for the D'Orbigny angrite. This old age indicates early partial melting on the UPB, consistent with the early accretion of the UPB (within 1 Ma after CAIs) predicted by thermal modeling. Furthermore, there is a 4∼5 Ma age difference between the external isochron in this study and internal isochron ages for the feldspathic clasts in polymict ureilites, which likely reflects an impact history during the early evolution of the UPB.

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Section: Timescale Of Upb's Evolutionsupporting

confidence: 82%

Chromium Isotopic Constraints on the Origin of the Ureilite Parent Body

Zhu

Moynier

Schiller

et al. 2020

ApJ

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“…On the contrary, Bizzarro et al. () show that the μ 54 Cr variation between chondrules is of the same scale as that of bulk chondrites and achondrites (see their figure 6.10), whereas the size of chondrules is three orders of magnitude smaller than that of asteroids, the parent bodies of chondrites. This observation establishes that the 54 Cr variability in chondrules cannot reflect a nugget effect related to the incorporation of an unidentified anomalous presolar carrier.…”

Section: Discussionmentioning

confidence: 93%

The role of Bells in the continuous accretion between the CM and CR chondrite reservoirs

Kooten

Cavalcante

Wielandt

et al. 2020

Meteorit & Planetary Scien

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CM meteorites are dominant members of carbonaceous chondrites (CCs), which evidently accreted in a region separated from the terrestrial planets. These chondrites are key in determining the accretion regions of solar system materials, since in Mg and Cr isotope space, they intersect between what are identified as inner and outer solar system reservoirs. In this model, the outer reservoir is represented by metal-rich carbonaceous chondrites (MRCCs), including CR chondrites. An important question remains whether the barrier between MRCCs and CCs was a temporal or spatial one. CM chondrites and chondrules are used here to identify the nature of the barrier as well as the timescale of chondrite parent body accretion. We find based on high precision Mg and Cr isotope data of seven CM chondrites and 12 chondrules, that accretion in the CM chondrite reservoir was continuous lasting <3 Myr and showing late accretion of MRCC-like material reflected by the anomalous CM chondrite Bells. We further argue that although MRCCs likely accreted later than CM chondrites, CR chondrules must have initially formed from a reservoir spatially separated from CM chondrules. Finally, we hypothesize on the nature of the spatial barrier separating these reservoirs.

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“…Both chronologies give comparable estimates for the duration of chondrule formation, ~4–5 Ma, providing a cosmochemical constraint on the lifetime of PPD (Bizzarro et al. ). However, contrary to the Al‐Mg chronology, the Pb‐Pb ages of individual chondrules (Connelly et al.…”

Section: Origin and Distribution Of 26al In The Ppdmentioning

confidence: 96%

“…5a), are dominant in most chondrites (Jones et al 2018). Porphyritic chondrules formed by incomplete melting of isotopically diverse solids, including CAIs, AOAs, chondrules of earlier generations , and fine-grained matrix-like material, during repeatable, localized transient heating events of still unknown nature in dust-rich regions of the PPD (e.g., Alexander et al 2008;Alexander and Ebel 2012;Hewins and Zanda 2012;Krot et al 2018a), inside and outside Jupiter (Van Kooten et al 2016;Bizzarro et al 2017;Kruijer et al 2017). High dust/gas ratios and/or high total pressure stabilized chondrule melts (Ebel and Grossman 2000) that behaved as open systems: SiO, Mg, Na, K, Mn, and Cr appear to have experienced evaporation and recondensation into chondrule melts (Libourel et al 2006;Hewins and Zanda 2012;Jones et al 2018;Libourel and Portail 2018).…”

Section: Major Chondritic Components and Their Proposed Originsmentioning

confidence: 99%

Refractory inclusions in carbonaceous chondrites: Records of early solar system processes

Krot

2019

Meteorit & Planetary Scien

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Chondrites consist of three major components: refractory inclusions (Ca,Al‐rich inclusions [CAIs] and amoeboid olivine aggregates), chondrules, and matrix. Here, I summarize recent results on the mineralogy, petrology, oxygen, and aluminum‐magnesium isotope systematics of the chondritic components (mainly CAIs in carbonaceous chondrites) and their significance for understanding processes in the protoplanetary disk (PPD) and on chondrite parent asteroids. CAIs are the oldest solids originated in the solar system: their U‐corrected Pb‐Pb absolute age of 4567.3 ± 0.16 Ma is considered to represent time 0 of its evolution. CAIs formed by evaporation, condensation, and aggregation in a gas of approximately solar composition in a hot (ambient temperature >1300 K) disk region exposed to irradiation by solar energetic particles, probably near the protoSun; subsequently, some CAIs were melted in and outside their formation region during transient heating events of still unknown nature. In unmetamorphosed, type 2–3.0 chondrites, CAIs show large variations in the initial 26Al/27Al ratios, from <5 × 10–6 to ~5.25 × 10–5. These variations and the inferred low initial abundance of 60Fe in the PPD suggest late injection of 26Al by a wind from a nearby Wolf–Rayet star into the protosolar molecular cloud core prior to or during its collapse. Although there are multiple generations of CAIs characterized by distinct mineralogies, textures, and isotopic (O, Mg, Ca, Ti, Mo, etc.) compositions, the 26Al heterogeneity in the CAI‐forming region(s) precludes determining the duration of CAIs formation using 26Al‐26Mg systematics. The existence of multiple generations of CAIs and the observed differences in CAI abundances in carbonaceous and noncarbonaceous chondrites may indicate that CAIs were episodically formed and ejected by a disk wind from near the Sun to the outer solar system and then spiraled inward due to gas drag. In type 2–3.0 chondrites, most CAIs surrounded by Wark–Lovering rims have uniform Δ17O (= δ17O−0.52 × δ18O) of ~ −24‰; however, there is a large range of Δ17O (from ~−40 to ~ −5‰) among them, suggesting the coexistence of 16O‐rich (low Δ17O) and 16O‐poor (high Δ17O) gaseous reservoirs at the earliest stages of the PPD evolution. The observed variations in Δ17O of CAIs may be explained if three major O‐bearing species in the solar system (CO, H2O, and silicate dust) had different O‐isotope compositions, with H2O and possibly silicate dust being 16O‐depleted relative to both the Genesis solar wind Δ17O of −28.4 ± 3.6‰ and even more 16O‐enriched CO. Oxygen isotopic compositions of CO and H2O could have resulted from CO self‐shielding in the protosolar molecular cloud (PMC) and the outer PPD. The nature of 16O‐depleted dust at the earliest stages of PPD evolution remains unclear: it could have either been inherited from the PMC or the initially 16O‐rich (solar‐like) MC dust experienced O‐isotope exchange during thermal processing in the PPD. To understand the chemical and isotopic composition of the protosolar MC...

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Chondrules: Ubiquitous Chondritic Solids Tracking the Evolution of the Solar Protoplanetary Disk

Cited by 18 publications

References 125 publications

Chromium Isotopic Constraints on the Origin of the Ureilite Parent Body

Chromium Isotopic Constraints on the Origin of the Ureilite Parent Body

The role of Bells in the continuous accretion between the CM and CR chondrite reservoirs

Refractory inclusions in carbonaceous chondrites: Records of early solar system processes

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