¹Scott A.Whattam,^2,3Roger H.Hewins,⁴Jieun Seo,⁵Bertrand Devouard
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2021.12.022]
¹Department of Geosciences, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
²IMPMC, Sorbonne Univ., MNHN, UPMC Paris 06, UMR CNRS 7590, 75005 Paris, France
³Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ 08854, United States
⁴Department of Earth and Environmental Sciences, Korea University, Seoul 02841, Korea
⁵Aix-Marseille Université, CNRS, IRD, CEREGE UM34, BP 80 Aix en Provence, 13545 France
Copyright Elsevier

The formation of chondrules involved major processes in the protoplanetary disk and therefore needs to be understood. Identifying possible precursors and the conditions of their transformation into chondrules is an essential step. Here we investigate whether refractory inclusions (RI) can be converted into Type IA chondrule analogs by isothermal heating and dynamic crystallization experiments, and report a new constraint on chondrule peak temperatures. We prepared synthetic calcium-aluminum-rich inclusions (CAI) by sintering <20 µm An + Di + Sp powder at 1200 °C and synthetic AOA analogs from crushed <5 µm Fo gel or San Carlos olivine mixed with nuggets of synthetic CAI. We used the AOA analogs as starting materials in experiments and were able to reproduce the textures and mesostasis compositions of Type IA chondrules. However, in the charges, the olivine lacks asymmetric zonation and our mesostasis compositions show olivine fractionation trends, two differences from Type I chondrules indicating the requirement of condensation of Mg and SiO in the latter. Relict spinel is present in isothermal runs up to 1550 °C, but is totally resorbed by 1600 °C. We conclude that CAI and AOA were sintered essentially at their condensation temperatures and are appropriate precursors for chondrules. Chondrules with relict spinel must have formed at <1600 °C, much lower than their liquidus temperatures (∼1750 °C). Such peak temperatures are consistent with models of condensation during chondrule formation. In typical chondrules with no inclusions of AOA or CAI, spinel is an indicator of their near complete assimilation. Grains of spinel (sensu stricto) in chondrules are relicts of RI and constitute a largely untapped cosmochemical resource for the investigation of chondrule provenance.

^1,2Andrea Patzer,¹Emma S.Bullock,¹ConelM. O’D. Alexander
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2021.12.021]
¹Earth and Planets Laboratory, Carnegie Institution for Science, 5241 Broad Branch Rd. NW, Washington D.C. 20015, USA
²Geosciences Center, University of Goettingen, Goldschmidtstr. 1, 37077 Goettingen, Germany
Copyright Elsevier

Knowing how the major chondritic components evolved and what their initial compositions were is pivotal for our understanding of the processes that shaped the early Solar System. Here, we have extended to the CR chondrites our testing of chondrule-matrix complementarity and the four-component model, i.e., two very different explanations for the bulk compositions of the carbonaceous chondrites and their components. Combining point-counting with electron microprobe analyses, we have analyzed four relatively primitive Antarctic CRs and the fall Renazzo. Our results for the abundances of chondrules and matrix are in good agreement with literature data, and confirm that these abundances vary considerably amongst the CRs (80.4 ±2.3 wt.% and 18.5 ±2.8 wt.%, respectively, in the four Antarctic CRs vs. 62.3 ±3.4 wt.% and 33.2 ±2.2 wt.% in Renazzo). The significant differences make the determination of the average properties and bulk compositions of the CRs problematic. This is particularly true for the volatile elements that were predominantly accreted in matrix. Nevertheless, all major and many minor element concentrations reported in the literature for average bulk CRs are reproduced here to better than 10 %. By comparing our results to conventionally determined bulk compositions, we were able to verify the accuracy of our approach and identify elements likely affected by alteration or analytical artifacts (e.g., Ti, K, Co). Two particular compositional details of the CR chondrites investigated are (a) the relatively high contents of Mn in the chondrules compared to CO chondrules, and (b) the depletion of S in the matrix, relative to CI. In terms of the major elements Mg, Al, Si and Ca, our data suggest that unaltered chondrules and matrix exhibited CI-like relative abundances, supporting previous conclusions for the CO chondrites. Where observed, deviations of element abundances in the matrix from CI (Na, Mg, S, Ca, Fe, Ni) can be explained in terms of alteration (parent body and terrestrial) and pre-accretionary loss of forsterite and, possibly, sulfides. Overall, our results are more consistent with the predictions of the four-component model than they are with chondrule-matrix complementarity.

¹Maxence Regnault,¹Yves Marrocchi,¹Maxime Piralla,¹Johan Villeneuve,²Valentina Batanova,¹Nicolas Schnuriger,³Emmanuel Jacquet
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13778]
¹CRPG, UMR 7358, Université de Lorraine, CNRS, Vandœuvre-lès-Nancy, 54501 France
²ISTerre, UMR 5275, CNRS, Université Grenoble Alpes, Grenoble, 38000 France
³IMPMC, UMR 7590, CNRS & Muséum national d’Histoire naturelle, CP52, 57 rue Cuvier, Paris, 75005 France
Published by arrangement with John Wiley & Sons

Rumurutiites (R chondrites) are rare, highly oxidized chondrites belonging to the noncarbonaceous superclan and characterized by low chondrule abundances. Although textural and chemical features of Rumurutiite chondrules resemble those of ordinary chondrites (OCs), their formation conditions and potential genetic link remain debated. Here, we report high-resolution elemental X-ray mapping analyses and in situ O isotopic measurements of olivine grains from five chondrules and eight isolated olivine grains (IOGs) in the NWA 12482 R3 chondrite. The chondrules show chemical zonings similar to their counterparts in ordinary and carbonaceous chondrites (CCs), implying that gas–melt interaction processes between chondrule precursors and SiO- and Mg-rich gas were operative throughout the circumsolar disk. Our isotopic data show that R chondrules are isotopically similar to ordinary chondrules, although differences in their abundances of relict olivine grains and chondrule textural characteristics suggest different formation environments, with R chondrules being formed from 16O-poorer precursors. As with chondrules in OCs, the O isotopic characteristics of R chondrules and IOGs suggest limited transport between CC and noncarbonaceous reservoirs.

¹Hideyuki Hayashi,²Takashi Mikouchi,³Nak Kyu Kim,³Changkun Park,^4,5Yuji Sano,^6,7Atsushi Takenouchi,⁶Akira Yamaguchi,⁸Hiroyuki Kagi,⁹Martin Bizzarro
Meteoritics & Planetary Science (in Press) Link to Article [https://onlinelibrary.wiley.com/doi/10.1111/maps.13776]
¹Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan
²The University Museum, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan
³Division of Earth Sciences, Korea Polar Research Institute (KOPRI), 26 Songdomirae-ro, Yeonsu-gu, Incheon, 21990 Korea
⁴Atmosphere and Ocean Research Institute (AORI), The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba, 277-8564 Japan
⁵Center for Advanced Marine Core Research, Kochi University, Monobe, Nankoku, Kochi, B200 783-8502 Japan
⁶Antarctic Meteorite Research Center, National Institute of Polar Research (NIPR), 10-3 Midori-cho, Tachikawa, Tokyo, 190-8518 Japan
⁷The Kyoto University Museum, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto, 606-8501 Japan
⁸Geochemical Research Center, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan
⁹Centre for Stars and Planet Formation, Globe Institute, University of Copenhagen, ØsterVoldgade 5-7, Copenhagen, DK-1350 Denmark
Published by arrangement with John Wiley & Sons

Northwest Africa (NWA) 7203 is a quenched angrite, showing mineralogical features typically not present in other quenched angrites. NWA 7203 exhibits textures whose grain size varies from fine grains (<10 μm) to coarse grains (~3 mm), while other quenched angrites show only single-sized textures. Fine-grained and coarse-grained lithologies have nearly the same bulk compositions. Cooling rates were estimated to be ~80 °C h⁻¹ for fine-grained lithologies and ~1 °C h⁻¹ for coarse-grained lithologies. Mg-rich olivines (~Fo₆₄) were found only in fine-grained lithologies. Crystallization of NWA 7203 started in the fine-grained lithologies with Mg-rich olivine grains acting as seeds for crystallization. Coarse-grained lithologies were subsequently formed under conditions of slower cooling. NWA 7203 shows clear shock metamorphic textures unlike other quenched angrites except for NWA 1670. We confirm that the oxygen isotopic ratios of NWA 7203 plot on the angrite fractionation line within uncertainty. However, the obtained Pb-Pb age of NWA 7203 is 4543 ± 19 Ma, younger than the ages of other quenched angrites, which might be a result of disturbance by shock metamorphism. The finding of shock metamorphism of NWA 7203 suggests that some angrites might be derived from asteroids that remained large (>10 km in diameter) during the late heavy bombardment.

¹Liubov V. Guda,¹Antonina N. Kravtsova,²Stanislav P. Kubrin,¹Alexander A. Guda,³Mikhail I. Mazuritskiy,¹Andrei A. Tereshchenko,⁴Yuri V. Popov,¹Alexander V. Soldatov
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13769]
¹The Smart Materials Research Institute, Southern Federal University, A. Sladkova str. 178/24, Rostov-on-Don, 344090 Russia
²Research Institute of Physics, Southern Federal University, Stachki ave. 194, Rostov-on-Don, 344090 Russia
³Physics Faculty, Southern Federal University, Sorge str. 5, Rostov-on-Don, 344090 Russia
⁴Institute of Earth Sciences, Southern Federal University, Sorge str. 40, Rostov-on-Don, 344090 Russia
Published by arrangement with john Wiley & Sons

Micro X-ray fluorescence (XRF) analysis, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Mössbauer and X-ray absorption near-edge structure (XANES) spectroscopies have been used to study the element and phase composition, and Fe and Ni oxidation states in ordinary chondrites. The meteorites have been initially classified as Markovka (H4 type), Polujamki (H4 type), Sayh al Uhaymir (SaU) 001 (L5 type), Dhofar (Dho) 020 (H4/5 type), and Jiddat al Harasis (JaH) 055 (L4-5 type). We have applied a set of spectroscopic methods to characterize and quantify the differences between samples. While the concentration of Fe in the meteorites is in agreement with the qualitative assignment of their types (L or H) made upon discovery, we observed extremely low Mg/Si and Al/Si values compared to the data published by Palme et al. (2014). Phase content of the meteorites has been studied by means of XRD, as well as by SEM and EDX. Mössbauer spectroscopy of Fe-containing phases has determined that Fe ions are present mainly in olivine and pyroxene phases in all studied samples. Goethite, hematite, and troilite phases were found in Markovka, Polujamki, and Sayh al Uhaymir 001, respectively. Markovka and Polujamki samples contained the largest concentration of Fe-Ni-Co metal grains. Fe and Ni K-XANES spectra were analyzed to estimate metal oxidation state in the chondrites and compared with the Mössbauer data. The multispectral data acquired in the present work are of importance for further understanding of meteoritic processes.

^1,2,3Zhuqing Xue,³Donald F. Welsh,³Clive R. Neal,⁴Long Xiao
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13767]
¹School of Marine Sciences, University of the Chinese Academy of Sciences, Beijing, 100049 China
²Center of Deep-Sea Research, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071 China
³Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, Indiana, 46556 USA
⁴School of Earth Sciences, China University of Geosciences, Wuhan, 430074 China
Published by arrangement with John Wiley & Sons

This paper represents a comprehensive crystal size distribution (CSD) study of ilmenite and plagioclase from 12 Apollo 11 basalts from four of the five compositional groups (Groups A, B1, B2, B3, and one unclassified basalt—Group “U” basalt 10062). Ilmenite was saturated in the magma at/before eruption, resulting in subsurface growth of phenocrysts (Group B1) and many small crystals upon eruption. Plagioclase always exhibits linear CSDs representing a single cooling regime in each sample, which is interpreted as crystallizing within isolated magma pockets late in the cooling of the erupted lava flow. Latent heat of crystallization and insulating effects of crystallized phases produced slower cooling and lower plagioclase nucleation densities. Exceptions are the Group B2 and B3 basalts, indicating relatively earlier crystallization of plagioclase on the lunar surface. Our study demonstrates that textures of the Apollo 11 basalts are a product of the interplay among cooling rate, bulk composition, and nucleation density during crystallization. Group A basalts have the highest cooling rates compared to the other Apollo 11 samples (except 10072,53), and were erupted through high effusion rates producing thick flows that underwent extended cooling that induced textural coarsening in both early crystallizing ilmenite and late-stage plagioclase. Group B1 lavas had the lowest effusion rates producing the thinnest flows. The Groups B2, B3, and U basalts are intermediate between these end members. Our approach can be used to define eruption environment, crystallization sequence, and cooling rate of samples collected on the Moon from non-bedrock sources.