Reassessing the origin and chronology of the unique achondrite Asuka 881394: Implications for distribution of 26Al in the early Solar System

Wimpenny, Josh; Sanborn, M. E.; Koefoed, Piers; Cooke, Ilsa R.; Stirling, Claudine H.; Amelin, Yuri; Yin, Qing‐Zhu

doi:10.1016/j.gca.2018.10.006

Cited by 28 publications

(39 citation statements)

References 103 publications

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“…Given the ongoing debate about the 26 Al distribution within the protoplanetary disk (e.g., Larsen et al 2011;Kita et al 2013;Bollard et al 2019), we elected to calculate absolute ages based on 26 Al-26 Mg relative to D'Orbigny (Schiller et al 2015), which has a nucleosynthetic makeup better matched with ureilites than CAIs. Moreover, Al-Mg ages are more consistent with U-Pb ages when anchored to D'Orbigny rather than CAIs (Wimpenny et al 2019). These ages are listed in (Qin et al 2010b), 4562.0±0.9 Ma ( 26 Al-26 Mg) and 4562.0±3.4 Ma (U-Pb) for ALM-A (Bischoff et al 2014;Amelin et al 2015), and 4563.6±0.7 Ma ( 53 Mn-53 Cr) for a main group ureilite (Yamakawa et al 2010).…”

Section: Upb Experienced An Impact Event 4∼5 Myr After Solar System Fmentioning

confidence: 61%

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: Upb Experienced An Impact Event 4∼5 Myr After Solar System Fmentioning

confidence: 61%

Chromium Isotopic Constraints on the Origin of the Ureilite Parent Body

Zhu

Moynier

Schiller

et al. 2020

ApJ

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“…Two of the cumulate gabbros are isotopically anomalous: A-881394 and EET 92023 with O-isotope anomalies of +16.0 and +16.5 MAD units from the HED igneous median (Table 2). A-881394 is well resolved from eucrites and diogenites in 54 Cr isotope ratios (Wimpenny et al 2019). The 54 Cr isotope ratio for EET 92023 plots intermediate between those of eucrites and the eucrite-type meteorites A-881394 and Bunburra Rockhole, which have O-isotope ratios like that of EET 92023; within uncertainty, EET 92023 overlaps the fields for both eucrite and eucrite-type achondrites in ε 54 Cr (Sanborn et al 2016).…”

Section: Cumulate Gabbrosmentioning

confidence: 97%

“…A-881394 is an ancient rock, with a Pb-Pb age of 4565 Ma (Wimpenny et al 2019). Short-lived 26 Al-26 Mg and 53 Mn-53 Cr chronometers give concordant ages (Nyquist et al 2003;Wadhwa et al 2009), but these ages are ~1 Ma younger than Pb-Pb ages (Wadhwa et al 2009;Wimpenny et al 2019).…”

Section: Cumulate Gabbrosmentioning

confidence: 99%

Eucrite‐type achondrites: Petrology and oxygen isotope compositions^†

Mittlefehldt

Greenwood

Berger

et al. 2021

Meteorit & Planetary Scien

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We report petrologic studies and oxygen isotope analyses of normal and anomalous eucrites, termed eucrite-type achondrites. Petrologically anomalous eucrite-type achondrites can have normal oxygen isotope compositions, and vice versa. Two basaltic eucrites with normal oxygen isotope compositions contain pyroxenes with anomalous Fe/Mn engendered by parent body processes acting on normal eucrites: solid-state reduction by S gas in EET 87542, and reduction during crystallization by magmatic S in QUE 94484. Cataclastic basaltic breccias PCA 82502 and PCA 91007 are paired (petrology, anomalous oxygen). Although isotopically like Pasamonte, they are petrologically distinct. We confirm the petrological and isotopic anomalies of cumulate gabbro EET 92023; likely formed by impact melting of mixed cumulate and basaltic materials. Many main group eucrites include plagioclases that retain near-liquidus compositions despite metamorphic overprinting. Stannern group eucrites contain more sodic plagioclase, which is consistent with the melt hybridization hypothesis for Stannern group magma formation. The lack of more calcic plagioclase suggests reactive exchange of the anorthite component of the primary melt with the albitic component of the crust. Asteroids that are modestly different in composition can produce virtually indistinguishable basalts, providing a ready explanation for the eucrite-type achondrite suite. Small stochastic variations in petrologic evolution can cause substantial differences in rocks produced on an asteroid. † This study is dedicated to the memory of John T. Wasson, friend and colleague, and for DWM, the mentor who molded him into the scientist he became.

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“…Mg have not been observed for bulk chondrites (e.g.,36,37) but are known in two ancient achondrites (NWA 7325: δ 26 Mg*0=0.093 ± 0.004‰(38); Asuka 881394: δ 26 Mg*0=0.070 ± 0.052‰, 39). They could result from metamorphic perturbations or redistributions(39), or correspond to the protolith isotopic composition in the case of remelting of a crustal reservoir(38,40). Here, these explanations are not satisfactory, due to the short cooling duration of EC 002, and the evidence that the andesitic magma formed directly from a chondritic source.…”

mentioning

confidence: 94%

A 4,565-My-old andesite from an extinct chondritic protoplanet

Barrat

Chaussidon

Yamaguchi

et al. 2021

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

120

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The age of iron meteorites implies that accretion of protoplanets began during the first millions of years of the solar system. Due to the heat generated by 26Al decay, many early protoplanets were fully differentiated with an igneous crust produced during the cooling of a magma ocean and the segregation at depth of a metallic core. The formation and nature of the primordial crust generated during the early stages of melting is poorly understood, due in part to the scarcity of available samples. The newly discovered meteorite Erg Chech 002 (EC 002) originates from one such primitive igneous crust and has an andesite bulk composition. It derives from the partial melting of a noncarbonaceous chondritic reservoir, with no depletion in alkalis relative to the Sun’s photosphere and at a high degree of melting of around 25%. Moreover, EC 002 is, to date, the oldest known piece of an igneous crust with a 26Al-26Mg crystallization age of 4,565.0 million years (My). Partial melting took place at 1,220 °C up to several hundred kyr before, implying an accretion of the EC 002 parent body ca. 4,566 My ago. Protoplanets covered by andesitic crusts were probably frequent. However, no asteroid shares the spectral features of EC 002, indicating that almost all of these bodies have disappeared, either because they went on to form the building blocks of larger bodies or planets or were simply destroyed.

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Reassessing the origin and chronology of the unique achondrite Asuka 881394: Implications for distribution of 26Al in the early Solar System

Cited by 28 publications

References 103 publications

Chromium Isotopic Constraints on the Origin of the Ureilite Parent Body

Chromium Isotopic Constraints on the Origin of the Ureilite Parent Body

Eucrite‐type achondrites: Petrology and oxygen isotope compositions^†

A 4,565-My-old andesite from an extinct chondritic protoplanet

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Reassessing the origin and chronology of the unique achondrite Asuka 881394: Implications for distribution of 26Al in the early Solar System

Cited by 28 publications

References 103 publications

Chromium Isotopic Constraints on the Origin of the Ureilite Parent Body

Chromium Isotopic Constraints on the Origin of the Ureilite Parent Body

Eucrite‐type achondrites: Petrology and oxygen isotope compositions†

A 4,565-My-old andesite from an extinct chondritic protoplanet

Contact Info

Product

Resources

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Eucrite‐type achondrites: Petrology and oxygen isotope compositions^†