Upper limits of water contents in olivine and orthopyroxene of equilibrated chondrites and several achondrites

1,2Dennis HARRIES,3Xuchao ZHAO,3Ian FRANCHI
Meteoritics & Planetary Science (in Press) Open Access Link to Article [doi: 10.1111/maps.13980]
1Department of Analytical Mineralogy, Institute of Geoscience, Friedrich Schiller University Jena, Carl-Zeiss-Promenade 10,07745 Jena, Germany
2European Space Resources Innovation Centre, Luxembourg Institute of Science and Technology, 41 rue du Brill, L-4422Belvaux, Luxembourg
3School of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
Published by arrangement with John Wiley & Sons

Hydroxyl defects in nominally anhydrous minerals (NAMs) were potential carriers ofwater in the early Solar System and might have contributed to the accretion of terrestrial water.To better understand this, we have conducted a nanoscale secondary ion mass spectrometrysurvey of water contents in olivine and orthopyroxene from a set of equilibrated ordinarychondrites of the L and LL groups (Baszk ́owka, Bensour, Kheneg Ljouˆad, and Tuxtuac) andseveral ultramafic achondrites (Zakøodzie, Dhofar 125, Northwest Africa [NWA] 4969, NWA6693, and NWA 7317). For calibration, we used terrestrial olivine and orthopyroxene with H2Ocontents determined by Fourier transform infrared. Our 99.7% (~3SD) detection limits are 3.6–5.4 ppmw H2O for olivine and 7.7–10.9 ppmw H2O for orthopyroxene. None of the meteoriticsamples studied consistently shows water contents above the detection limits. A few exceptionsslightly above the detection limits are suspected of terrestrial contamination by ferricoxyhydroxides. If the meteorite samples investigated accreted in the presence of small amountsof water ice, the upper limits of water contents provided by our survey suggest that the retentionof hydrogen during thermal metamorphism and differentiation was ineffective. We suggest thatloss occurred through combinations of low internal pressures, high permeability along grainboundaries, and speciation of hydrogen into reduced compounds such as H2and methane,which are less soluble in NAMs than in water.

The Santa Filomena meteorite shower: Trajectory, classification, and opaque phases as indicators of metamorphic conditions

1,2Amanda Tosi et al. (>10)
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13976]
1LABSONDA/IGEO/UFRJ, Instituto de Geociências, Universidade Federal do Rio de Janeiro, Av. Athos da Silveira Ramos, 274, Cidade Universitária, 21941-972 Rio de Janeiro, RJ, Brazil
2LABET/MN/UFRJ, Laboratório Extraterrestre, Departamento de Geologia e Paleontologia, Museu Nacional, Universidade Federal do Rio de Janeiro, Quinta da Boa Vista, São Cristóvão, 20940-040 Rio de Janeiro, RJ, Brazil
Published by arrangement with John Wiley & Sons

On August 19, 2020, at 13:18—UTC, a meteor event ended as a meteorite shower in Santa Filomena, a city in the Pernambuco State, northeast Brazil. The heliocentric orbital parameters resulting from images by cameras of the weather broadcasting system were semimajor axis a = 2.1 ± 0.1 au, eccentricity e = 0.55 ± 0.03, and inclination i = 0.15o ± 0.05. The data identified the body as an Apollo object, an Earth-crossing object with a pericenter interior to the Earth’s orbit. The chemical, mineralogical, and petrological evaluations, as well as the physical analysis, followed several traditional techniques. The meteorite was identified as a H5-6 S4 W0 ordinary chondrite genomict breccia. The large amount of metal in the meteorite made a metallographic evaluation based on the opaque phases possible. The monocrystalline kamacite crystals suggest a higher petrological type and the distorted Neumann lines imply at least two different shock events. The absence of the plessite phase shows that the meteorite did not reach the highest shock levels S5 and S6. The well-defined polycrystalline taenite is indicative of petrologic types 4 and 5 due to the conserved internal tetrataenite rim at the boundaries. The presence of polycrystalline taenites and the characteristics of the Agrell Effect suggest that the Santa Filomena meteorite did not reheat above 700°C. The absence of martensite confirms reheating temperatures <800°C and a slow cooling rate. The Ni contents and sizes of the zoned taenite particles indicate a slow cooling rate ranging from 1 to 10 K Myr−1.

Using the potassium-argon laser experiment (KArLE) to date ancient, low-K chondritic meteorites

1,2,3Fanny CATTANI,2Barbara A. COHEN,4Cameron M. MERCER,5Agnes J. DAHL
Meteoritics & Planetary Science 58, 591-611 Open Access Link to Article [doi: 10.1111/maps.13960]
1The Catholic University of America, Washington, DC, USA
2Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
3Center for Research and Exploration in Space Science and Technology, NASA/GSFC, Greenbelt, Maryland, USA
4U.S. Geological Survey, Geology, Geophysics, Geochemistry Science Center, Denver, Colorado, USA
5Department of Earth Sciences, University of Gothenburg, Goteborg, Sweden
Published by arrangement with John Wiley & Sons

Several laboratories have been investigating the feasibility of in situ K-Ar dating foruse in future landing planetary missions. One drawback of these laboratory demonstrations isthe insufficient analogy of the analyzed analog samples with expected future targets. Wepresent the results obtained using the K-Ar laser experiment (KArLE) on two old and K-poorchondritic samples, Pułtusk and Hvittis, as better lunar analogs. The KArLE instrument useslaser ablation to vaporize rock samples and quantifies K content by laser-induced breakdownspectroscopy (LIBS), Ar by quadrupole mass spectrometry (QMS), and ablated mass by laserprofilometry. We performed 64 laser ablations on the chondrites to measure spots with a rangeof K2O and Ar content and used the data to construct isochrons to determine the chondriteformation age. The KArLE isochron ages on Pułtusk and Hvittis are 5059892 Ma and4721793 Ma, respectively, which is within the uncertainty of published reference ages, andinterpreted as the age of their formation. The uncertainty (2σ) on the KArLE ages obtained inthis study is better than 20% (18% for Pułtusk and 17% for Hvittis). The precision, whichcompares our obtained ages to the reference ages, is also better than 20% (11% for Pułtuskand 4% for Hvittis). These results are encouraging for understanding the limits of thistechnique to measure ancient planetary samples and for guiding future improvements to theinstrument.

Earth shaped by primordial H2 atmospheres

1Edward D. Young,2Anat Shahar,1Hilke E. Schlichting
Nature 616, 306-311 Link to Article [DOI https://doi.org/10.1038/s41586-023-05823-0]
1Department of Earth, Planetary, and Space Sciences, University of California Los Angeles, Los Angeles, CA, USA
2Carnegie Institution for Science, Earth and Planets Laboratory, Washington, DC, USA

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Extended time scales of carbonaceous chondrite aqueous alteration evidenced by a xenolith in LaPaz Icefield 02239 (CM2)

1Martin R. LEE,1Cameron FLOYD,1Pierre-Etienne MARTIN,2Xuchao 2 A. FRANCHI,1Laura JENKINS,1Sammy GRIFFIN
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.13978]
1School of Geographical and Earth Sciences, University of Glasgow, Glasgow G12 8QQ, UK2School of Physical
2Sciences, Open University, Milton Keynes MK7 6AA, UK*Corresponding author.Martin R. Lee, School of Geographical and Earth Sciences, University of Glasgow, Glasgow G12 8QQ, UK
Published by arrangement with John Wiley & Sons

LaPaz Icefield (LAP) 02239 is a mildly aqueously altered CM2 carbonaceouschondrite that hosts a xenolith from a primitive chondritic parent body. The xenolithcontains chondrules and calcium- and aluminum-rich inclusions (CAIs) in a very fine-grained matrix. The chondrules are comparable in mineralogy and oxygen isotopiccomposition with those in the CMs, and its CAIs are also mineralogically similar to the CMpopulation apart for being unusually small and abundant. The presence of serpentinedemonstrates that the xenolith has been aqueously altered, and its phyllosilicate-rich matrixhas a comparable oxygen isotopic composition to the matrices of CM meteorites. Thexenolith’s chondrules lack fine-grained rims, whereas the xenolith itself has a fine-grainedrim that is petrographically and chemically comparable with the rims on coarse grainedobjects in LAP 02239 and other CM meteorites. These properties show that the xenolith’sparent body was formed from similar materials to the CM parent body(ies). Following itslithification by aqueous alteration, a piece of the xenolith’s parent body was impact-ejected,acquired a fine-grained rim while free-floating in the protoplanetary disc, then was accretedalong with rimmed chondrules and other materials to make the LAP 02239 parent body.Subsequent aqueous processing of the LAP 02239 parent body altered the fine-grained rimson the xenolith, chondrules, and CAIs. The xenolith shows that the timespan of geologicalevolution of carbonaceous chondrite parent bodies was sufficiently long for some of them tohave been aqueously altered before others had formed.INTRODUCTIONThe Mighei-like (CM) carbonaceous chondrite (CC)meteorites have close spectroscopic affinities to C-complexasteroids (Burbine,2016) and so likely sample one or moreof them. The parent body(ies) of the CMs were formed bythe accretion of relatively coarse-grained objects (i.e.,chondrules and calcium- and aluminum-rich inclusions[CAIs]) together with fine-grained material that formsthe enclosing matrix (Barber,1981; McSween Jr. &Richardson,1977). The chondrules and other coarse-grainedobjects typically have fine-grained rims that they acquiredwhile free-floating in the protoplanetary disc (Hanna &Ketcham,2018; Metzler et al.,1992). The constituents of thecoarse-grained objects, fine-grained rims and matrix(anhydrous silicates, metal, sulfides, oxides, and amorphousmaterials) were partially to completely altered by parentbody aqueous activity at~4563 Ma (Bunch & Chang,1980;Fujiya et al.,2012; McSween Jr.,1979a,1979b). Theresultant secondary minerals are volumetrically dominatedby phyllosilicates that are intergrown with carbonates,oxides, and sulfides (Barber,1981; Bunch & Chang,1980;Fuchs et al.,1973;Howardetal.,2009,2011,2015;Leeet al.,2014; Tomeoka & Buseck,1985;Trigo-Rodrıguezet al.,2019; Zolensky et al.,1993).TheCMsareclassifiedby petrologic type/subtype using various properties thatMeteoritics & Planetary Science1–16 (2023)doi: 10.1111/maps.139781Ó2023 The Authors.Meteoritics & Planetary Sciencepublished by Wiley Periodicals LLC on behalf of The Meteoritical Society.This is an open access article under the terms of theCreative Commons AttributionLicense, which permits use,distribution and reproduction in any medium, provided the original work is properly cited.

Curation planning and facilities for asteroid Bennu samples returned by the OSIRIS-REx mission

1K.Righter et al.(>10)
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13973]
1NASA Johnson Space Center, Houston, Texas, USA
Published by arrangement with John Wiley & Sons

NASA’s OSIRIS-REx spacecraft collected samples from carbonaceous near-Earth asteroid (101955) Bennu on October 20, 2020, and will deliver them to the Earth on September 24, 2023. The samples will be processed at the NASA Johnson Space Center (JSC), where most of the sample collection will be subsequently curated in a new cleanroom suite. The spacecraft collected loose regolith two ways: in a bulk sample chamber capable of holding up to 2 kg, and on industrial Velcro “contact pads” intended to collect small particles at the surface. Included in the JSC collection will be the bulk sample, the contact pads, contamination-monitoring witness plates, and supporting hardware. Planning for the curation of the samples and hardware started at the earliest phase of proposal development and continued in parallel with project development and execution. Because a major mission goal is characterization of organic compounds in the Bennu samples, extra effort was spent in the design stage to ensure a clean curation environment. Here, we describe the preparations to receive the sample, including the design, construction, outfitting, and monitoring of the cleanrooms at JSC; the planned recovery of the sample-containing capsule when it lands on Earth; and the approach to characterizing and cataloging the samples. These curation efforts will result in the distribution of pristine Bennu samples from JSC to the OSIRIS-REx science team, international partners, and the global scientific community for years to come.

Evidence for multiple early impacts on the H chondrite parent body from electron backscatter diffraction analysis

1Secana P. GOUDY,1Myriam TELUS,2Brendan CHAPMAN
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.13969]
1Earth and Planetary Sciences, University of California, Santa Cruz, Santa Cruz, California, USA2School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA
2Earth and Planetary Sciences, University of California, Santa Cruz, CA 95064, USA
Published by arrangement with John Wiley & Sons

We examined H4 chondrites Beaver Creek, Forest Vale, Quenggouk, Ste. Marguerite, and Sena with the electron backscatter diffraction (EBSD) techniques of Ruzicka and Hugo (2018) to determine if there is evidence for shock metamorphism consistent with the previously inferred histories of their early impact excavation or lack thereof. We find that all samples have EBSD data consistent with a history of synmetamorphic impact shock (i.e., shock during thermal metamorphism), followed by postshock annealing. Petrographic analysis of Sena, Quenggouk, and Ste. Marguerite found exsolved Cu and irregular troilite within Fe metal, features consistent with shock metamorphism. All samples have a spatial variability in grain deformation consistent with shock processes, though Forest Vale, Quenggouk, and Ste. Marguerite may have relict signatures of accretional deformation as indicated by variability in their olivine deformation metrics. Within the context of previous workers’ geochemical observations, a more complex history is inferred for each sample. The “slow-cooled” samples, Quenggouk and Sena, were subject to synmetamorphic shock without excavation and annealed at depth. The same is true of the “fast-cooled” samples, Beaver Creek, Forest Vale, and Ste. Marguerite. However, after annealing, these rocks were excavated by a secondary impact or impacts around 5.2–6.5 Ma post-CAI formation and were left to cool rapidly on the surface of the H chondrite parent body. These interpreted histories are best compatible with a model of an impact-battered but intact onion shell for the earliest history of the H parent body. However, the EBSD evidence does not preclude a parent body disruption after 7 Ma post-CAI formation.

Hydrogen isotopic evidence for nebular pre-hydration and the limited role of parent-body processes in CM chondrites

1Yves Marrocchi,1Thomas Rigaudier,1Maxime Piralla,1Laurette Piani
Earth and Planetary Science Letters 611, 118151 Link to Article [https://doi.org/10.1016/j.epsl.2023.118151]
1Université de Lorraine, CNRS, CRPG, UMR 7358, Nancy, France
Copyright Elsevier

The conditions and environments in which hydrated phases in unequilibrated meteorites formed remain debated. Among carbonaceous chondrites, Mighei-type chondrites (CMs) display a large range in the degree of aqueous alteration, and thus record different stages of hydration and alteration. Here, we report the bulk H, C, and N contents, H and C isotopic compositions, and thermogravimetric signatures of the most- and least-altered CMs known so far, Kolang and Asuka 12236, respectively. We also report in-situ SIMS measurements of the hydrogen isotopic compositions of water in both chondrites. Compared to other CMs, Asuka 12236 has the lowest bulk water content (3.3 wt.% H2O) and the most D-rich water and bulk isotopic compositions (δD = 180‰ and 280‰, respectively). Combined with literature data, our results show that phyllosilicate-bearing CMs altered to varying degrees accreted water-ice grains with similar isotopic compositions. These results demonstrate that the hydrogen isotopic variations in CM chondrites (i) are not controlled by secondary alteration processes and (ii) were mostly shaped by interactions between the protoplanetary disk and the molecular cloud that episodically fed the disk over several million years. The minimally altered CM chondrites Paris and Asuka 12236 display peculiar, D-rich, hydrogen isotopic compositions that imply the presence of another H-bearing component in addition to insoluble organic matter and phyllosilicates. This component is most likely the hydrated amorphous silicates that are ubiquitous in these chondrites. CM bulk H and O isotopic compositions are linearly correlated, implying that (i) amorphous silicates in CM matrices were already hydrated by disk processes before the onset of CM parent-body alteration, and (ii) the quest for a hypothetically water-free CM3 is illusory.

Mass-dependent nickel isotopic variations in achondrites and lunar rocks

1Shui-Jiong Wang,2Shi-Jie Li,3Yangting Lin,1Si-Zhang Sheng
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2023.04.004]
1State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences (Beijing), Beijing 100083, China
2Center for Lunar and Planetary Sciences, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
3Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China]
Copyright Elsevier

We present high-precision mass-dependent nickel isotopic data for a comprehensive suite of achondrites and lunar rocks, providing key insights into the early planetary differentiation and Earth-Moon system formation. The primitive achondrites display high Ni contents and invariant Ni isotopic compositions. Incomplete core-mantle differentiation in primitive achondrite parent bodies resulted in the retention of metal in the mantle, which dominated the Ni budget and accounted for the bulk chondritic Ni isotopic values. The highly reduced differentiated achondrites, aubrites and an ungrouped achondrite (NWA 8409), have variable, and extremely light Ni isotopic compositions. Acid leaching experiments demonstrate that the sulfides are a significant host of light Ni isotopes in aubrites. The most extreme Ni isotope values of aubrites may be due to large Ni isotope fractionation accompanied by silicate-sulfide-metal separation during differentiation of the parent bodies, and subsequent global disruptive collision and reassembly with variably high proportions of sulfides enriched in the mantle. The howardite-eucrite-diogenite (HED) meteorites show Ni isotopic variations that are positively correlated with Ni/Co ratios, a feature that cannot be produced by igneous differentiation. Late accretion of high-Ni and high-Ni/Co chondritic materials after core formation of their likely parent body, Vesta, could have accounted for this correlation. Thus, the primitive silicate mantle of Vesta may have sub-chondritic Ni isotopic compositions, implying possible Ni isotope fractionation during core-mantle differentiation of small planet bodies. The lunar breccia meteorites have homogenously chondritic Ni isotope values, together with their high Ni/Co of bulk rock and metals therein, suggesting impact contamination. Lunar basalt meteorites have low Ni/Co ratios and are systematically isotopically lighter than the breccias, displaying a positive correlation between Ni isotope value and Ni/Co ratio, as that seen in the HEDs. Therefore, the Ni isotopic systematics in lunar rocks also indicates the effect of late accretion, with the primitive lunar mantle having sub-chondritic Ni isotope values. This implies that the Moon-forming impactor, Theia, was likely an aubrite-like differentiated planetary body whose mantle was enriched in light Ni isotopes. We suggest that there was significant Ni isotope fractionation between core and mantle during differentiation of early formed small planetary bodies, but this signature can be obscured by late accretion in the bulk achondrite records.

Structural changes in shocked tektite and their implications to impact-induced glass formation

1,2Toshimori Sekine,2Tsubasa Tobase,3Youjun Zhang,4Ginga Kitahara,4Akira Yoshiasa,5Tomoko Sato,6Takamichi Kobayashi,7Akihisa Mori
American Mineralogist 108, 686-694 Link to Article [http://www.minsocam.org/msa/ammin/toc/2023/Abstracts/AM108P0686.pdf]
1Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China
2Graduate School of Engineering, Osaka University, Suita 565-0871, Japan
3Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
4Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan
5Department of Earth and Planetary Systems Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
6National Institute for Materials Science, Tsukuba 305-0044, Japan
7Department of Mechanical Engineering, Sojo University, Kumamoto 860-0082, Japan
Copyright: The Mineralogical Society of America

Heavy meteorite impacts on Earth’s surface produce melt and vapor that are quenched rapidly and
scattered over wide areas as natural glasses with various shapes and characteristic chemistry, which
are known as tektites and impact glasses. Their detailed formation conditions have long been debated
using mineralogical and geochemical data and numerical simulations of impact melt formations. These
impact processes are also related to the formation and evolution of planets. To unravel the formation
conditions of impact-induced glasses, we performed shock recovery experiments on a tektite. Recovered samples were characterized by X-ray diffraction, Raman spectroscopy, and X-ray absorption fine
structure spectroscopy on the Ti K-edge. Results indicate that the densification by shock compression
is subjected to post-shock annealing that alters the density and silicate-framework structures but that
the local structures around octahedrally coordinated Ti ions remain in the quenched glass. The relationship between the average Ti-O distance and Ti K pre-edge centroid energy is found to distinguish the
valance state of Ti ions between Ti4+ and Ti3+ in the glass. This relationship is useful in understanding
the formation conditions of impact-derived natural glasses. The presence of Ti3+ in tektites constrains
the formation conditions at extremely high temperatures or reduced environments. However, impact
glasses collected near the impact sites do not display such conditions, but instead relatively mild and
oxidizing formation conditions. These different formation conditions are consistent with the previous
numerical results on the crater size dependence.