Origin and chronology of chondritic components: A review

Krot, Alexander N.; Amelin, Yuri; Bland, P. A.; Ciesla, F. J.; Connelly, James N.; Davis, A. M.; Huss, G. R.; Hutcheon, I. D.; Makide, K.; Nagashima, K.; Nyquist, L. E.; Russell, S. S.; Scott, E. R. D.; Thrane, Kristine; Yurimoto, H.; Yin, Qing‐Zhu

doi:10.1016/j.gca.2008.09.039

Cited by 180 publications

(174 citation statements)

References 170 publications

(286 reference statements)

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“…Chondritic meteorites (chondrites) are fragments of early-formed planetesimals that avoided melting and differentiation and, therefore, provide a record of the earliest evolutionary stages of the Sun and its protoplanetary disk. Most chondrites contain calcium−aluminum-rich inclusions (CAIs) and chondrules, which formed by high-temperature processes that included evaporation, condensation, and melting during short-lived heating events (3). CAIs represent the oldest dated solids and, thus, define the age of the Solar System at 4,567.3 ± 0.16 Ma (4).…”

mentioning

confidence: 99%

“…Chondrule formation started contemporaneously with CAIs and continued for several million years (4). Chondrules appear to have formed in different disk regions and sampled a wider range of radial distances from the Sun than CAIs (3). Collectively, chondritic components provide time-sequenced samples allowing us to probe the composition of the disk material that accreted to form planetesimals and planets.…”

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confidence: 99%

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Isotopic evidence for primordial molecular cloud material in metal-rich carbonaceous chondrites

Kooten

Wielandt

Schiller

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

173

124

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The short-lived 26 Al radionuclide is thought to have been admixed into the initially 26 Al-poor protosolar molecular cloud before or contemporaneously with its collapse. Bulk inner Solar System reservoirs record positively correlated variability in mass-independent 54 Cr and 26 Mg*, the decay product of 26 Al. This correlation is interpreted as reflecting progressive thermal processing of infalling 26 Al-rich molecular cloud material in the inner Solar System. The thermally unprocessed molecular cloud matter reflecting the nucleosynthetic makeup of the molecular cloud before the last addition of stellar-derived 26 Al has not been identified yet but may be preserved in planetesimals that accreted in the outer Solar System. We show that metal-rich carbonaceous chondrites and their components have a unique isotopic signature extending from an inner Solar System composition toward a 26 Mg*-depleted and 54 Cr-enriched component. This composition is consistent with that expected for thermally unprocessed primordial molecular cloud material before its pollution by stellar-derived 26 Al. The 26 Mg* and 54 Cr compositions of bulk metal-rich chondrites require significant amounts (25-50%) of primordial molecular cloud matter in their precursor material. Given that such high fractions of primordial molecular cloud material are expected to survive only in the outer Solar System, we infer that, similarly to cometary bodies, metal-rich carbonaceous chondrites are samples of planetesimals that accreted beyond the orbits of the gas giants. The lack of evidence for this material in other chondrite groups requires isolation from the outer Solar System, possibly by the opening of disk gaps from the early formation of gas giants. molecular cloud | outer Solar System | metal-rich chondrites | isotopes | chondrite accretion regions L ow-mass stars like our Sun form by the gravitational collapse of the densest parts of molecular clouds comprising stellarderived dust and gas. Collapsing clouds swiftly evolve into deeply embedded protostars that rapidly accrete material from their surrounding envelopes via a protoplanetary disk (1), in which planetesimals and planetary embryos form over timescales of several million years (2). Chondritic meteorites (chondrites) are fragments of early-formed planetesimals that avoided melting and differentiation and, therefore, provide a record of the earliest evolutionary stages of the Sun and its protoplanetary disk. Most chondrites contain calcium−aluminum-rich inclusions (CAIs) and chondrules, which formed by high-temperature processes that included evaporation, condensation, and melting during short-lived heating events (3). CAIs represent the oldest dated solids and, thus, define the age of the Solar System at 4,567.3 ± 0.16 Ma (4). It is inferred that CAIs formed near the proto-Sun during a brief time interval (<0

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confidence: 99%

mentioning

confidence: 99%

Isotopic evidence for primordial molecular cloud material in metal-rich carbonaceous chondrites

Kooten

Wielandt

Schiller

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

173

124

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“…It is suggested that the accretion time of asteroids determines the degree of metamorphism (and/or melting) they experienced 1 , because a short-lived radionuclide of 26 Al (half-life: 0.73×10 6 years) is the dominant heat source of metamorphism, and hence, the abundance of the heat source is a function of accretion time. Several lines of evidence from the dating of meteorites have shown that the parent bodies of differentiated meteorites accreted earlier than chondrites 2,3 . These observations indicate that accretion time is indeed an important controlling factor of asteroidal thermal history, whereas other factors, such as water concentrations in asteroids, could have minor roles.…”

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confidence: 99%

Evidence for the late formation of hydrous asteroids from young meteoritic carbonates

et al. 2012

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The accretion of small bodies in the solar system is a fundamental process that was followed by planet formation. Chronological information of meteorites can constrain when asteroids formed. secondary carbonates show extremely old 53 mn-53 Cr radiometric ages, indicating that some hydrous asteroids accreted rapidly. However, previous studies have failed to define accurate mn/Cr ratios; hence, these old ages could be artefacts. Here we develop a new method for accurate mn/Cr determination, and report a reliable age of 4,563.4+0.4/-0.5 million years ago for carbonates in carbonaceous chondrites. We find that these carbonates have identical ages, which are younger than those previously estimated. This result suggests the late onset of aqueous activities in the solar system. The young carbonate age cannot be explained if the parent asteroid accreted within 3 million years after the birth of the solar system. Thus, we conclude that hydrous asteroids accreted later than differentiated and metamorphosed asteroids.

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“…The majority of CAIs in unmetamorphosed chondrites contain high abundance of radiogenic 26 Mg ( 26 Mg*), the decay product of 26 Al (t 1/2 ∼ 0.7 Ma), corresponding to an inferred initial 26 Al/ 27 Al ratio of ∼(4.5-5.5) × 10 -5 (6). Recent high-precision 26 Al- 26 Mg systematics of bulk CV CAIs define the so-called canonical 26 Al/ 27 Al ratio of (5.252 ± 0.019) × 10 -5 (7).…”

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confidence: 99%

“…8] and inclusions (6,9) have low initial 26 Al/ 27 Al ratios (<5 × 10 -6 ). Of particular interest are the coarse-grained igneous inclusions with fractionation and unidentified nuclear effects (FUN CAIs, ref.…”

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confidence: 99%

¹⁸² Hf– ¹⁸² W age dating of a ²⁶ Al-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System

Holst

Olsen

Paton

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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Refractory inclusions [calcium–aluminum-rich inclusions, (CAIs)] represent the oldest Solar System solids and provide information regarding the formation of the Sun and its protoplanetary disk. CAIs contain evidence of now extinct short-lived radioisotopes (e.g., 26 Al, 41 Ca, and 182 Hf) synthesized in one or multiple stars and added to the protosolar molecular cloud before or during its collapse. Understanding how and when short-lived radioisotopes were added to the Solar System is necessary to assess their validity as chronometers and constrain the birthplace of the Sun. Whereas most CAIs formed with the canonical abundance of 26 Al corresponding to 26 Al/ 27 Al of ∼5 × 10 −5 , rare CAIs with fractionation and unidentified nuclear isotope effects (FUN CAIs) record nucleosynthetic isotopic heterogeneity and 26 Al/ 27 Al of <5 × 10 −6 , possibly reflecting their formation before canonical CAIs. Thus, FUN CAIs may provide a unique window into the earliest Solar System, including the origin of short-lived radioisotopes. However, their chronology is unknown. Using the 182 Hf– 182 W chronometer, we show that a FUN CAI recording a condensation origin from a solar gas formed coevally with canonical CAIs, but with 26 Al/ 27 Al of ∼3 × 10 −6 . The decoupling between 182 Hf and 26 Al requires distinct stellar origins: steady-state galactic stellar nucleosynthesis for 182 Hf and late-stage contamination of the protosolar molecular cloud by a massive star(s) for 26 Al. Admixing of stellar-derived 26 Al to the protoplanetary disk occurred during the epoch of CAI formation and, therefore, the 26 Al– 26 Mg systematics of CAIs cannot be used to define their formation interval. In contrast, our results support 182 Hf homogeneity and chronological significance of the 182 Hf– 182 W clock.

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Origin and chronology of chondritic components: A review

Cited by 180 publications

References 170 publications

Isotopic evidence for primordial molecular cloud material in metal-rich carbonaceous chondrites

Isotopic evidence for primordial molecular cloud material in metal-rich carbonaceous chondrites

Evidence for the late formation of hydrous asteroids from young meteoritic carbonates

¹⁸² Hf– ¹⁸² W age dating of a ²⁶ Al-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System

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Origin and chronology of chondritic components: A review

Cited by 180 publications

References 170 publications

Isotopic evidence for primordial molecular cloud material in metal-rich carbonaceous chondrites

Isotopic evidence for primordial molecular cloud material in metal-rich carbonaceous chondrites

Evidence for the late formation of hydrous asteroids from young meteoritic carbonates

182 Hf– 182 W age dating of a 26 Al-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System

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¹⁸² Hf– ¹⁸² W age dating of a ²⁶ Al-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System