Abundant presolar silicates of the CM chondrite Asuka 12169: Implications for the thermal and aqueous alteration of the CM parent body

Xu, Yuchen; Lin, Yangting; Hao, Jialong; Kimura, Makoto; Hu, Sen; Yang, Wei; Liu, Yang; Zou, Yongliao

doi:10.1016/j.gca.2022.07.016

Cited by 2 publications

(3 citation statements)

References 101 publications

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“…For example, analyses of CM3.0, A 12169, revealed numerous occurrences of these grains, as the entire sample area was covered (Nittler et al., 2021; Xu et al., 2022). Subtype 2.9 chondrites contain a lower abundances of oxygen‐rich presolar grains than in subtype 3.0 CM, CO, and others (e.g., Nittler et al., 2021; Xu et al., 2022). Such presolar grains are easily susceptible to alteration.…”

Section: Discussionmentioning

confidence: 99%

Subtype 3.0 chondrites: Petrologic classification criteria

Kimura,

Weisberg,

Yamaguchi

2024

Meteorit & Planetary Scien

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Type 3 chondrites are subdivided into 3.0–3.9. Subtype 3.0 chondrites nearly preserve all of their primitive features. Many criteria have been proposed to distinguish such primitive chondrites. Here, we compiled mineral data and reconsider the petrologic classification criteria for subtype 3.0. Chondrites are classified into subtypes by the minor element distribution of olivine and textural and chemical features of Fe‐Ni metal. The []Si4O8 and MgO components of feldspar also distinguish subtype 3.0 from subtypes ≥3.1. Other features, such as the occurrence of near pure chromite, are also indicators of subtype 3.0. It is difficult to distinguish between subtypes 3.0 and ≤2.9 based on mineral chemistry. Therefore, we propose the following criteria to distinguish between subtypes 3.0 and ≤2.9. In type 3.0 chondrites, major silicate (olivine, pyroxene, and plagioclase), oxide, metal, and sulfide minerals do not show aqueous alteration features. Melilite, anorthite, and glass show no or mild aqueous alteration features. Subtype 3.0 has not been identified in all chondrite groups. The absence of subtype 3.0 from some groups mainly reflects differences in the degrees of secondary parent body processes among the chondrite groups.

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Section: Discussionmentioning

confidence: 99%

Subtype 3.0 chondrites: Petrologic classification criteria

Kimura,

Weisberg,

Yamaguchi

2024

Meteorit & Planetary Scien

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“…Because aqueous parent body alteration alters silicates to hydrous silicates, it is thought to erase presolar isotopic signatures (Lodders and Amari, 2005). For example, Asuka 12169, which is thought to be the most unaltered CM chondrite, has a presolar silicate concentration of ~185 ppm, while the aqueously altered Murchison meteorite has a presolar silicate concentration of ~8 ppm (Zinner, 2014;Xu et al, 2022). The potential effects of aqueous alteration and thermal metamorphism on the preservation of isotopic anomalous signatures is therefore an important factor to considered for any study on heavily altered meteorites.…”

Section: The Carriers Of Nucleosynthetic Anomaliesmentioning

confidence: 99%

“…To give a basic assessment for the influence of thermal metamorphism on presolar grains in NWA 11346, the volatile element abundances can be examined, since volatile loss has been suggested to occur during thermal metamorphism on meteorite parent bodies (e.g., Nakamura, 2005;Amsellem et al, 2020). The significant depletions of volatile elements (especially Na, Cs, Pb, Rodriguez and Blum, 2009;Floss and Haenecour, 2016;Xu et al, 2022). For Aguas Zarcas, the effects of the aqueous alteration would likely have resulted in the destruction of some presolar grains preserved (thus diluting the isotopic anomalous signatures) especially given that Aguas Zarcas has been shown to have been aqueously altered (Kerraouch et al, 2021(Kerraouch et al, , 2022.…”

Section: Parent Body History and Secondary Alteration Effects On Isot...mentioning

confidence: 99%

Trace element and strontium and barium isotopic variability of CM chondrites Aguas Zarcas and NWA 11346: Insights from stepwise acid leaching

McGovern

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<p><strong>Carbonaceous chondrite meteorites represent unmelted but variably metamorphosed aggregates of a diverse range of the earliest solids of the solar system, including matrix, chondrules, calcium-aluminium inclusions and exotic presolar grains. As such, they preserve a record of the inventory of materials that were first brought together in the evolving protoplanetary disk then were subjected to processes such as thermal and aqueous alteration on their parent body. To gain further insights into the elemental and isotopic variability of primitive meteorites and their components, stepwise acid leaching experiments were carried out on pre-rain collected 2019 fall CM2 Aguas Zarcas and anomalous-CM find NWA 11346 carbonaceous chondrites. Pre-rain collected fall samples of primitive meteorites in particular are exceptionally rare; thus the Aguas Zarcas sample provides an excellent opportunity to study materials essentially unaffected by any terrestrial alteration imprint. Acid leachates and bulk samples were analysed for trace elements (including the rare earth elements) via ICP-MS, while Sr and Ba isotopes were measured using TIMS. Trace element variations reveal diverse compositions for bulk samples and their leachates, interpreted to reflect differing parent body histories and the contrasting impacts of terrestrial contamination. Sr isotopic analysis of leach fractions yields variable (primordial) µ84Sr values compared to the NBS987 terrestrial standard, ranging from +326 to -2089 ppm in Aguas Zarcas and from +46 to -559 ppm in NWA 11346. Both Aguas Zarcas and NWA 11346 show the strongest depletions of µ84Sr in the strongest acid leachates; however, the variability of µ84Sr among Aguas Zarcas leachates differs from the same leaching steps for NWA 11346. Bulk meteorite Sr isotopic analysis of Aguas Zarcas and NWA 11346 yields values indistinguishable from the standard. For Ba isotopes, bulk Aguas Zarcas shows resolvable depletions in 130Ba, 135Ba, 137Ba and 138Ba, while NWA 11346 shows similar depletions in 135Ba, 137Ba and 138Ba. Early Aguas Zarcas leachates are characterised by positive anomalies of 130Ba, 132Ba, 135Ba, 137Ba and 138Ba (up to +2295 ppm µ130Ba). In contrast, final leachates of both samples show strong depletions for the same nuclides, the largest of which are -60,000 ppm µ130Ba in Aguas Zarcas and -4370 ppm µ130Ba in NWA 11346. The Sr and Ba isotopic variability between samples and their respective leachates suggests input from multiple nucleosynthetic sources, highlighting the diversity among CM chondrites and the heterogenous distribution of nuclides in the protoplanetary disk.</strong></p>

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Abundant presolar silicates of the CM chondrite Asuka 12169: Implications for the thermal and aqueous alteration of the CM parent body

Cited by 2 publications

References 101 publications

Subtype 3.0 chondrites: Petrologic classification criteria

Subtype 3.0 chondrites: Petrologic classification criteria

Trace element and strontium and barium isotopic variability of CM chondrites Aguas Zarcas and NWA 11346: Insights from stepwise acid leaching

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