Plagioclase alteration and equilibration in ordinary chondrites: Metasomatism during thermal metamorphism

Lewis, J. A.; Jones, R. H.; Brearley, Adrian J.

doi:10.1016/j.gca.2021.10.004

Cited by 16 publications

(10 citation statements)

References 75 publications

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“…The bulk chondrite LF‐XRD patterns for all UOCs are similar and indicate that the major constituents of these meteorites are olivine (with variable Mg/Fe contents) and pyroxene (mainly low‐Ca), with lesser amounts of Fe‐sulfide (troilite) and metal (Figure 3). Minor plagioclase is also likely present in some meteorites (e.g., Lewis et al., 2022), but identification was challenging because its main diffraction peaks overlap with those from the more abundant olivine and pyroxene. No diffraction peaks from phyllosilicates are observed above the background in any of the UOCs; however, there is a magnetite peak in the XRD pattern for Ngawi (Figure 3), and all of the finds have a peak attributed to goethite.…”

Section: Resultsmentioning

confidence: 99%

“…This is consistent with the presence of a poorly crystalline (“amorphous”), Fe‐bearing component, which will fluoresce due to the use of Cu radiation and, therefore, contribute to the background of the XRD pattern (e.g., Bland et al., 2004; King et al., 2015). Candidate phases in ordinary chondrites include Fe‐rich weathering products (e.g., “rusts”), phyllosilicates/clays (e.g., Menzies et al., 2005), amorphous silicates (e.g., Dobrică & Brearley, 2020), and/or chondrule glass (e.g., Krot & Rubin, 1994; Lewis et al., 2022; Lewis & Jones, 2019). For Bishunpur and Krymka, we attempted to fit the intensity and overall shape of the remaining residuals using a combination of our Fe‐(oxy)hydroxide, serpentine–smectite, and synthetic amorphous silicate standards and, in both cases, found reasonable agreement with the phyllosilicates (when scaled and excluding the diffraction peaks).…”

Section: Resultsmentioning

confidence: 99%

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Bulk mineralogy, water abundance, and hydrogen isotope composition of unequilibrated ordinary chondrites

Grant

Tartèse

Jones

et al. 2023

Meteorit & Planetary Scien

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The origin and transport of water in the early Solar System is an important topic in both astrophysics and planetary science, with applications to protosolar disk evolution, planetary formation, and astrobiology. Of particular interest for understanding primordial water transport are the unequilibrated ordinary chondrites (UOCs), which have been affected by very limited alteration since their formation. Using X‐ray diffraction and isotope ratio mass spectrometry, we determined the bulk mineralogy, H2O content, and D/H ratios of 21 UOCs spanning from petrologic subtypes 3.00–3.9. The studied UOC falls of the lowest subtypes contain approximately 1 wt% H2O, and water abundance globally decreases with increasing thermal metamorphism. In addition, UOC falls of the lowest subtypes have elevated D/H ratios as high as those determined for some outer Solar System comets. This does not easily fit with existing models of water in the protoplanetary disk, which suggest D/H ratios were low in the warm inner Solar System and increased radially. These new analyses confirm that OC parent bodies accreted a D‐rich component, possibly originating from either the outer protosolar nebula or from injection of molecular cloud streamers. The sharp decrease of D/H ratios with increasing metamorphism suggests that the phase(s) hosting this D‐rich component is readily destroyed through thermal alteration.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Bulk mineralogy, water abundance, and hydrogen isotope composition of unequilibrated ordinary chondrites

Grant

Tartèse

Jones

et al. 2023

Meteorit & Planetary Scien

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“…Plagioclase is a mineral that has been observed in a variety of CCs and OCs, including CR chondrites (Tenner et al, 2019), CV chondrites (Krot et al, 2002), and type 5 and 6 OCs (Huss et al, 2006; Van Schmus & Wood, 1967). In OCs, plagioclase has been observed as a primary phase (Lewis et al, 2022). Given the ubiquity of plagioclase, the presence of this mineral in particle #29 is not a selective feature for the purpose of constraining a range of possible parent bodies.…”

Section: Resultsmentioning

confidence: 99%

Non‐protein amino acids identified in carbon‐rich Hayabusa particles

Parker

Chan

Glavin

et al. 2022

Meteorit & Planetary Scien

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Amino acid abundances in acid-hydrolyzed hot water extracts of gold foils containing five Category 3 (carbon-rich) Hayabusa particles were studied using liquid chromatography with tandem fluorescence and accurate mass detection. Initial particle analyses using field emission scanning electron microscopy with energy-dispersive X-ray spectrometry indicated that the particles were composed mainly of carbon. Prior to amino acid analysis, infrared and Raman microspectroscopy showed some grains possessed primitive organic carbon. Although trace terrestrial contamination, namely L-protein amino acids, was observed in all Hayabusa extracts, several terrestrially uncommon non-protein amino acids were also identified. Some Hayabusa particles contained racemic (D≈L) mixtures of the non-protein amino acids β-aminoisobutyric acid (β-AIB) and β-amino-n-butyric acid (β-ABA) at low abundances ranging from 0.09 to 0.31 nmol g −1 . Larger abundances of the non-protein amino acid β-alanine (9.2 nmol g −1 , ≈4.5 times greater than background levels) were measured in an extract of three Hayabusa particles. This β-alanine abundance was ≈6 times higher than that measured in an extract of a CM2 Murchison grain processed in parallel. The comparatively high β-alanine abundance is surprising as asteroid Itokawa is similar to amino acid-poor LL ordinary chondrites. Elevated β-alanine abundances and racemic β-AIB and β-ABA in Hayabusa grains suggested these compounds have nonbiological and plausibly non-terrestrial origins. These results are the first evidence of plausibly extraterrestrial amino acids in asteroid material from a sample-return mission and demonstrate the capabilities of the analytical protocols used to study asteroid Ryugu and Bennu samples returned by the JAXA Hayabusa2 and NASA OSIRIS-REx missions, respectively.

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“…5 ) in contact with MV1b. The bands across the Opx are likely mechanical twin planes (indicated by white arrows) due to shock 5 . Further, at the contact with MV, Opx is transformed to majorite (#6; Raman spectrum MV1b-6 in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…In more equilibrated OCs, phyllosilicates are even more rare or totally absent, however phases other than phyllosilicates do indicate alteration in these objects. Metasomatic processes are recorded in OCs from types 3.6 to 3.9 by the presence of sodalite, scapolite, and nepheline; and from types 4.0 to 6.0 by albite and K-bearing feldspar 5 .…”

Section: Introductionmentioning

confidence: 99%

Unique evidence of fluid alteration in the Kakowa (L6) ordinary chondrite

Baziotis

Guan

et al. 2022

Sci Rep

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Meteorites preserve evidence of processes on their parent bodies, including alteration, metamorphism, and shock events. Here we show that the Kakowa (L6) ordinary chondrite (OC) preserves both shock-melt veins and pockets of detrital grains from a brecciated and altered object, including corundum, albite, silica, fayalite, forsterite, and margarite in a Pb- and Fe-rich matrix. Preservation of the observed mineralogy and texture requires a sequence of at least two impacts: first, a high-velocity collision formed the shock melt veins containing the high-pressure minerals ringwoodite, wadsleyite, majorite, and albitic jadeite; later, a low-velocity impact formed fractures and filled them with the detrital material. Oxygen and Pb isotope ratios suggest an OC origin for these detrital minerals. Although fluid alteration is common in carbonaceous chondrites, the discovery of margarite with an OC oxygen isotopic signature is novel. Kakowa extends both the impact and alteration history of L6 ordinary chondrites in general.

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Plagioclase alteration and equilibration in ordinary chondrites: Metasomatism during thermal metamorphism

Cited by 16 publications

References 75 publications

Bulk mineralogy, water abundance, and hydrogen isotope composition of unequilibrated ordinary chondrites

Bulk mineralogy, water abundance, and hydrogen isotope composition of unequilibrated ordinary chondrites

Non‐protein amino acids identified in carbon‐rich Hayabusa particles

Unique evidence of fluid alteration in the Kakowa (L6) ordinary chondrite

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