Linxi Li, Hejiu Hui, Sen Hu, Hao Wang, Wei Yang, Yi Chen, Shitou Wu, Lixin Gu, Lihui Jia, Fuyuan Wu
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14072]
Published by arrangement with John Wiley & Sons

The regolith samples returned by the Chang’E-5 mission (CE-5) contain the youngest radiometrically dated mare basaltic clasts, which provide an opportunity to elucidate the magmatic activities on the Moon during the late Eratosthenian. In this study, detailed petrographic observations and comprehensive geochemical analyses were performed on the CE-5 basaltic clasts. The major element concentrations in individual plagioclase grain of the CE-5 basalts may vary slightly from core to rim, whereas pyroxene has clear chemical zonation. The crystallization sequence of the CE-5 mare basalts was determined using petrographic and geochemical relations in the basaltic clasts. In addition, both fractional crystallization (FC) and assimilation and fractional crystallization models were applied to simulate the chemical evolution of melt equilibrated with plagioclase in CE-5 basalts. Our results reveal that the melt had a TiO₂ content of ~3 wt% and an Mg# of ~45 at the onset of plagioclase crystallization, suggesting a low-Ti parental melt of the CE-5 basalts. The relatively high FeO content (>14.5 wt%) in melt equilibrated with plagioclase could have resulted in extensive crystallization of ilmenite, unlike in Apollo low-Ti basalts. Furthermore, our calculations showed that the geochemical evolution of CE-5 basaltic melt could not have occurred in a closed system. On the contrary, the CE-5 basalts could have assimilated mineral, rock, and glass fragments that have higher concentrations of KREEP elements (potassium, rare earth elements, and phosphorus) in the regolith during magma flow on the Moon’s surface. The presence of the KREEP signature in the CE-5 basalts is consistent with literature remote sensing data obtained from the CE-5 landing site. These KREEP-bearing fragments could originate from KREEP basaltic melts that may have been emplaced at the landing site earlier than the CE-5 basalts.

Alexander N. Krot, Kazuhide Nagashima, Marina A. Ivanova, Dante Lauretta, Guy Libourel, Brandon C. Johnson, Frank E. Brenker, Viktoria Hoffman, Martin Bizzarro
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14072]
Published by arrangement with John Wiley & Sons

The CB (Bencubbin-like) metal-rich carbonaceous chondrites are subdivided into the CB_aand CB_b subgroups. The CB_a chondrites are composed predominantly of ~cm-sized skeletal olivine chondrules and unzoned Fe,Ni-metal ± troilite nodules. The CB_bchondrites are finer grained than the CB_as and consist of chemically zoned and unzoned Fe,Ni-metal grains, Fe,Ni-metal ± troilite nodules, cryptocrystalline and skeletal olivine chondrules, and rare refractory inclusions. Both subgroups contain exceptionally rare porphyritic chondrules and no interchondrule fine-grained matrix, and are interpreted as the products of a gas–melt impact plume formed by a high-velocity collision between differentiated planetesimals about 4562 Ma. The anomalous metal-rich carbonaceous chondrites, Fountain Hills and Sierra Gorda 013 (SG 013), have bulk oxygen isotopic compositions similar to those of other CBs but contain coarse-grained igneous clasts/porphyritic chondrule-like objects composed of olivine, low-Ca-pyroxene, and minor plagioclase and high-Ca pyroxene as well as barred olivine and skeletal olivine chondrules. Cryptocrystalline chondrules, zoned Fe,Ni-metal grains, and interchondrule fine-grained matrix are absent. In SG 013, Fe,Ni-metal (~80 vol%) occurs as several mm-sized nodules; magnesiochromite (Mg-chromite) is accessory; daubréelite and schreibersite are minor; troilite is absent. In Fountain Hills, Fe,Ni-metal (~25 vol%) is dispersed between chondrules and silicate clasts; chromite and sulfides are absent. In addition to a dominant chondritic lithology, SG 013 contains a chondrule-free lithology composed of Fe,Ni-metal nodules (~25 vol%), coarse-grained olivine and low-Ca pyroxene, interstitial high-Ca pyroxene and anorthitic plagioclase, and Mg-chromite. Here, we report on oxygen isotopic compositions of olivine, low-Ca pyroxene, and ±Mg-chromite in Fountain Hills and both lithologies of SG 013 measured in situ using an ion microprobe. Oxygen isotope compositions of olivine, low-Ca pyroxene, and Mg-chromite in these meteorites are similar to those of magnesian non-porphyritic chondrules in CB_aand CB_b chondrites: on a three-isotope oxygen diagram (δ¹⁷O vs. δ¹⁸O), they plot close to a slope-1 (primitive chondrule mineral) line and have a very narrow range of Δ¹⁷O (=δ¹⁷O–0.52 × δ¹⁸O) values, −2.5 ± 0.9‰ (avr ± 2SD). No isotopically distinct relict grains have been identified in porphyritic chondrule-like objects. We suggest that magnesian non-porphyritic (barred olivine, skeletal olivine, cryptocrystalline) chondrules in the CB_as, CB_bs, and porphyritic chondrule-like objects in SG 013 and Fountain Hills formed in different zones of the CB impact plume characterized by variable pressure, temperature, cooling rates, and redox conditions. The achondritic lithology in SG 013 represents fragments of one of the colliding bodies and therefore one of the CB chondrule precursors. Fountain Hills was subsequently modified by impact melting; Fe,Ni-metal and sulfides were partially lost during this process.

Christian Zeeden^a,b, Jacques Laskar^a, David De Vleeschouwer^d, Damien Pas^e, Anne-Christine Da Silva^c
Earth and Planetary Science Letters (in Press) Link to Article [https://doi.org/10.1016/j.epsl.2023.118348]
^aIMCCE, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, 75014 Paris, France
^bLIAG – Leibniz Institute for Applied Geophysics, Stilleweg 2, 30655 Hannover, Germany
^cPétrologie sédimentaire, B20, Allée du Six Août, 12, Quartier Agora, Liège University, Sart Tilman, 4000 Liège, Belgium
^dInstitute of Geology and Paleontology, Westfälische Wilhelms-Universität (WWU) Münster, Corrensstr 24, 48149 Münster, Germany
^eInstitute of Earth Sciences (ISTE), University of Lausanne, CH-1015 Lausanne, Switzerland
Copyright : Elsevier

Astronomical insolation forcing plays an important role in pacing Earth’s climate history, including paleoclimate dynamics, and its imprint can be seen in various geoarchives. Its signature is often evident through typical rhythmic patterns in sediments. The detailed study of those patterns led to a better understanding of orbital climate forcing, while also providing more precise constraints on the geological time scale. Due to the tidal evolution in the Earth-Moon system, the precession and obliquity periods get shorter when going back in time while the main eccentricity 405 kyr period remains stable. While several astrophysical models describe the evolution of the length of precession- and obliquity cycles, few reliable and quantitative geological information from tidalitesand astrochronology are available.

To better constrain these key astronomical parameters in the distant past, we calculate precession and obliquity properties for the Devonian (∼420-360 million years before present) as reconstructed from a suite of geological datasets. Our results show the period of precession to be 19.4-16.1 kyr, and the dominant p+s3 obliquity period to be 29.50±0.46 long. These findings are compared with and support the presence of oceanic tidal resonances at 300 and 540 Ma, as shown in the recent AstroGeo22 model of the Earth-Moon evolution of (Farhat et al., 2022).

Jonas PAPE¹, Bidong ZHANG², Fridolin SPITZER³, Alan E. RUBIN², andThorsten KLEINE³
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14075]
¹Institut für Planetologie, University of Münster, Münster, Germany
²Department of Earth, Planetary & Space Sciences, University of California, Los Angeles, California, USA
³Max Planck Institute for Solar System Research, Göttingen, Germany
Published by arrangement with John Wiley & Sons

Complex interelement trends among magmatic IIIF iron meteorites are difficult to explain by fractional crystallization and have raised uncertainty about their genetic relationships. Nucleosynthetic Mo isotope anomalies provide a powerful tool to assess if individual IIIF irons are related to each other. However, while trace element data are available for all nine IIIF irons, Mo isotopic data are limited to three samples. We present Mo isotopic data for all but one IIIF irons that help assess the genetic relationships among these irons, together with new Mo and W isotopic data for Fitzwater Pass (classified IIIF), and the Zinder pallasite (for which a cogenetic link with IIIF irons has been proposed). After correction for cosmic-ray exposure, the Mo isotopic compositions of the IIIF irons are identical within uncertainty and confirm their belonging to carbonaceous chondrite (CC)-type meteorites. The mean Mo isotopic composition of group IIIF overlaps those groups IIF and IID, but a common parent body for these groups is ruled out based on distinct trace element systematics. The new Mo isotopic data do not argue against a single parent body for the IIIF irons, and suggest a close genetic link among these samples. In contrast, Fitzwater Pass has distinct Mo and W isotopic compositions, identical to those of some non-magmatic IAB irons. The Mo and W isotope data for Zinder indicate that this meteorite is not related to IIIF irons, but belongs to the non-carbonaceous (NC) type and has the same Mo and W isotopic composition as main-group pallasites.

Bidong ZHANG^1,2, Yangting LIN³, Jialong HAO³, Devin L. SCHRADER^4,5,Meenakshi WADHWA⁵, Randy L. KOROTEV⁶, William K. HARTMANN⁷, andAudrey BOUVIER^2,8
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14078]
¹Department of Earth, Planetary and Space Sciences, University of California, Los Angeles, Los Angeles, California, USA
²Department of Earth Sciences, The University of Western Ontario, Ontario, London, Canada
³Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing,China
⁴Buseck Center for Meteorite Studies, Arizona State University, Arizona,Tempe, USA
⁵School of Earth and Space Exploration, Arizona State University, Arizona,Tempe, USA
⁶Department of Earth and Planetary Sciences and McDonnell Center for the Space Sciences, Washington University, St. Louis,Missouri, USA
⁷Planetary Science Institute, Arizona,Tucson, USA
⁸Bayerisches Geoinstitut, Universität Bayreuth, Bayreuth, Germany
Published by arrangement with John Wiley & Sons

About half of the lunar meteorites in our collections are feldspathic breccias. Acquiring geochronologic information from these breccias is challenging due to their low radioactive-element contents and their often polymict nature. We used high-spatial-resolution (5 μm) NanoSIMS (nanoscale secondary ion mass spectrometry) U-Pb dating technique to date micro-zircons in the lunar feldspathic meteorites Dhofar 1528 and Dhofar 1627. Three NanoSIMS dating spots of two zircon grains from Dhofar 1528 show a discordia with an upper intercept at 4354 ± 76 Ma and a lower intercept at 332 ± 1407 Ma (2σ, MSWD = 0.01, p = 0.91). Three spots of two zircon grains in Dhofar 1627 define a discordia with an upper intercept at 3948 ± 30 Ma and a lower intercept at 691 ± 831 Ma (2σ, MSWD = 0.40, p = 0.53). Both samples likely experienced shock metamorphism caused by impacts. Based on the clastic nature, lack of recrystallization and the consistent U-Pb and Pb-Pb dates of the zircons in Dhofar 1528, the U-Pb date of 4354 Ma is interpreted as the crystallization age of its Mg-suite igneous precursor. Some of the Dhofar 1627 zircons show poikilitic texture, a crystallization from the matrix impact melt, so the U-Pb date of 3948 Ma corresponds to an impact event, likely the Imbrium basin-forming event. These data are the first radiometric ages for these two meteorites and demonstrate that in situ (high spatial resolution) U-Pb dating has potential for extracting geochronological information about igneous activities and impact events from lunar feldspathic and polymict breccias.

James F. J. BRYSON, Claire I. O. NICHOLS, and Conall MAC NIOCAILL
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14079]
Department of Earth Sciences, University of Oxford, Oxford, UK
Published by arrangement with John Wiley & Sons

One key feature of our protoplanetary disk that shaped its transformation into a system of planetary bodies was its vast magnetic field. Unique constraints on the properties of this field can be gleaned from paleomagnetic measurements of certain meteorites. Here, we apply this approach to the recent CM chondrite fall Winchcombe with the aim of constructing the most complete and reliable record to date of the behavior of the disk field in the outer solar system. We find that the interior of Winchcombe carries a stable, pre-terrestrial magnetization that likely dates from the period of aqueous alteration of the CM chondrite parent body. This remanence corresponds to a paleointensity of 31 ± 17 μT accounting for the average effect of parent body rotation. Winchcombe is rich in framboids and plaquettes of magnetite, which formed via precipitation following the dissolution of iron sulfide. This contrasts with most other CM chondrites, where magnetite formed predominantly via pseudomorphic replacement of FeNi metal. Accounting for the potential differences in recording fidelities of these types of magnetite, we find that the reported paleointensities from all CM chondrites to date are likely underestimates of the disk field intensity in the outer solar system, and use our measurements to calculate a unified intensity estimate of ~78 μT. This paleointensity is consistent with two independent values from recent studies, which collectively argue that the disk field could have played a larger role in shaping the behavior of the disk in the outer solar system than previously considered.

Addi BISCHOFF¹, Markus PATZEK², Tommaso DI ROCCO², Andreas PACK²,Aleksandra STOJIC¹, Jasper BERNDT³, and Stefan PETERS⁴
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14074]
¹Institut für Planetologie, University of Münster, Münster, Germany
³Institut für Planetologie, University of Münster, Münster, Germany
³Geowissenschaftliches Zentrum, Universität Göttingen, Göttingen, Germany
⁴Institut für Mineralogie, University of M ̈unster, M ̈unster, Germany4Museum der Natur Hamburg—Mineralogie, LIB, Hamburg, Germany
Published by arrangement with John Wiley & Sons

On February 13, 2023, a huge fireball was visible over Western Europe (fireball event 2023 CX₁). After the possible strewn field was calculated, the first of several recovered samples, with a mass of about 100 g, was discovered just 2 days after the fireball event on the ground of the village of Saint-Pierre-le-Viger. Meanwhile, more than 60 samples with a total mass of more than 1 kg were recovered and a piece of one of these is studied here. The fall occurred 220 years after the historic meteorite fall of L’Aigle on April 26, 1803, <120 km south. L’Aigle is the closest meteorite fall to Saint-Pierre-le-Viger and belongs to the same chondrite group. Both meteorites are breccias containing only clasts of high metamorphic degree (type 5 and type 6). Since only 20% of the L chondrites are breccias this coincidence is remarkable. As just mentioned, both samples studied from these rocks in this work are ordinary chondrite breccias and consist of equilibrated and recrystallized lithologies of petrologic type 6. The brecciated texture in L’Aigle, resulting in a remarkable light–dark structure, is more pronounced than the brecciated features in Saint-Pierre-le-Viger, from which also type 5 fragments have been reported. The compositions of low-Ca pyroxene and olivine grains in Saint-Pierre-le-Viger (Fs_21.2 and Fa_23.4, respectively) clearly require an L-group classification. L’Aigle was classified as an L6 breccia in the past, and this has now been confirmed by new data on low-Ca pyroxene and olivine (Fs_20.7 and Fa_23.8, respectively). Saint-Pierre-le-Viger contains local thin shock veins, and both meteorites are moderately shocked. Most olivines in the studied samples have planar fractures, but the estimated abundance of mosaicized olivines of 30%–40% among the large grains require a S4 shock classification. Oxygen isotope and bulk chemical data of Saint-Pierre-le-Viger certainly support the L chondrite classification. Bulk spectral data of Saint-Pierre-le-Viger are dominated by silicate minerals, that is, Fe-bearing low-Ca pyroxene, olivine, and plagioclase. Isotopic, chemical, and spectral data of the L’Aigle meteorite are shown for comparison and are very similar, providing additional circumstantial evidence of Saint-Pierre-le-Viger’s L chondritic nature.

^1,2Schmitz, Birger,¹Terfelt, Fredrik
Estonian Journal of Earth Sciences 72, 94-97 Open Access Link to Article [DOI 10.3176/EARTH.2023.49]
¹Astrogeobiology Laboratory, Department of Physics, Lund University, Sweden
²Robert A. Pritzker Center for Meteoritics, Polar Studies, Field Museum of Natural History, Chicago, United States

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

¹Ke Wen,²Peng Yang,^1,3Mengqiang Zhu
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2023.08.028]
¹Department of Ecosystem Science and Management, University of Wyoming, Laramie, Wyoming 82071, United States
²Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
³Department of Geology, University of Maryland, College Park, Maryland 20742, United States
Copyright Elsevier

The occurrence of manganese (Mn) oxides on Mars is believed to be an indicator of an O2-rich paleoenvironment of Mars because Mn oxides often form through the oxidation of Mn(II) by O2 on the surface of Earth. An alternative formation pathway was recently proposed, in which Mn(II) is oxidized by bromate (BrO3-), a common oxidant in contemporary Martian regolith. However, the oxidation of Mn(II) by bromate in solution is kinetically controlled and slow unless using very high concentrations (100 mM) of reactants that may be irrelevant to the conditions of Mars. We conducted laboratory simulations to determine whether iron (Fe) oxides (hematite and goethite) and a phyllosilicate (montmorillonite), abundant minerals on the surface of Mars, could catalyze the oxidation of Mn(II) by bromate. Hematite and goethite, but not montmorillonite, dramatically accelerated the oxidation with a low concentration (1 mM) of Mn(II) and bromate under various solution conditions. The reaction system was autocatalytic with Fe oxides initiating the oxidation of Mn(II) at the early stage and the subsequent catalysis mainly provided by the Mn oxide products. In contrast to producing Mn(IV)O2 only during the homogeneous oxidation of Mn(II) by bromate in solutions, the heterogeneous mineral-surface catalyzed oxidation resulted in a mixture of Mn(III)OOH and Mn(IV)O2 phases. Mn(III)OOH was an intermediate product and can be further oxidized by bromate to Mn(IV)O2. The occurrence and accumulation of the intermediate product MnOOH can be attributed to its rapid formation due to surface-enhanced nucleation and growth on Fe oxide surfaces and to its higher resistance to oxidation by bromate than Mn(III) ions or clusters. Overall, mineral-surface catalyzed oxidation of Mn(II) by bromate is favorable from both thermodynamic and kinetic perspectives, and can be a major pathway for the occurrence of Mn oxides on Mars where microorganisms are lacking to catalyze the reaction. Our study further improves our understanding of the thermodynamic and kinetic controls on Mn(II) oxidation.

¹Xeynab Mouti Al-Hashimi,¹Jemma Davidson,¹Devin L. Schrader,²Emma S. Bullock
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14076]
¹Buseck Center for Meteorite Studies, School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA
²Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC, USA
Published by arrangement with John Wiley & Sons

The Mighei-like carbonaceous (CM) chondrites, the most abundant carbonaceous chondrite group by number, further our understanding of processes that occurred in their formation region in the protoplanetary disk and in their parent body/bodies and provide analogs for understanding samples returned from carbonaceous asteroids. Chondrules in the CMs are commonly encircled by fine-grained rims (FGRs) whose origins are debated. We present the abundances, sizes, and petrographic observations of FGRs in six CMs that experienced varying intensities of parent body processing, including aqueous and thermal alteration. The samples studied here, in approximate order of increasing thermal alteration experienced, are Allan Hills 83100, Murchison, Meteorite Hills 01072, Elephant Moraine 96029, Yamato-793321, and Pecora Escarpment 91008. Based on observations of these CM chondrites, we recommend a new average apparent (2-D) chondrule diameter of 170 μm, which is smaller than previous estimates and overlaps with that of the Ornans-like carbonaceous (CO) chondrites. Thus, we suggest that chondrule diameters are not diagnostic for distinguishing between CM and CO chondrites. We also argue that chondrule foliation noted in ALH 83100, MET 01072, and Murchison resulted from multiple low-intensity impacts; that FGRs in CMs formed in the protoplanetary disk and were subsequently altered by both aqueous and thermal secondary alteration processes in their parent asteroid; and that the heat experienced by some CM chondrites may have originated from solar radiation of their source body/bodies during close solar passage as evidenced by the presence of evolved desiccation cracks in FGRs that formed by recurrent wetting and desiccation cycles.