¹D. Fernandes,^1,2N. G. Rudraswami,¹M. Pandey,^1,2V. P. Singh
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14143]
¹National Institute of Oceanography (Council of Scientific and Industrial Research), Dona Paula, Goa, India
²Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
Published by arrangement with John Wiley & Sons

Fe-rich relict olivine grains are found in a small percentage of cosmic spherules, which are studied here to determine the nature of their precursors. We examined 128 Fe-rich relict olivine grains with Fa >10 mol% from 53 cosmic spherules of different types collected from Antarctica (Antarctica micrometeorites [AMM]) and deep-sea sediments (DSS) of the Indian Ocean. Fe-rich olivines identified in cosmic spherules are close analogs of type II chondrule olivines formed in the early solar system. The olivine analysis shows well-defined trends in molar Fe/Mn versus Fe/Mg with an affinity for ordinary and carbonaceous chondrites. The minor oxides in olivine are in ranges such as MnO ~0.1–0.8 wt%, Cr2O3 ~0–0.7 wt%, CaO ~0–0.6 wt%, and Al2O3 ~0–0.2 wt%, respectively. The chemical composition suggests that the precursors for these Fe-rich olivine-bearing cosmic spherules consist of ordinary chondrites (~21%–23%, AMM-DSS), carbonaceous chondrites (~17%–36%, AMM-DSS), and a large fraction overlapping both carbonaceous and ordinary chondrites (~41%–62% AMM-DSS). The elemental ratios Fe/Si/CI and Mg/Si/CI for the Fe-rich relict olivines ranging between the values 0.5–1.0 and 1.1–1.7 are compatible with IDPs, Comet 81P/Wild 2 as well as the Asteroid Itokawa and Ryugu, which are indistinguishable from carbonaceous and ordinary chondrites. In addition, pyroxene and olivine assemblages in their Fa versus Fs mol% show strong similarities to EOC chondrites. Our results on Fe-rich relict olivines show that these grains in cosmic spherules are less common than Mg-rich olivines, which show a narrow range of chemical compositions identical to those from ordinary chondrites and carbonaceous chondrites, indicating a supplementary contribution of an ordinary chondritic component to the micrometeorite source of dust.

¹Christian Vollmer,^2,3Demie Kepaptsoglou,^4,5Jan Leitner,²Aleksander B. Mosberg,^2,3Khalil El Hajraoui,⁶Ashley J. King,^6,7Charlotte L. Bays,⁶Paul F. Schofield,^8,9Tohru Araki,^2,10Quentin M. Ramasse
Nature Communications 15, 778 Open Access Link to Article [DOI
https://doi.org/10.1038/s41467-024-45064-x%5D
¹Institut für Mineralogie, Universität Münster, Münster, Germany
²SuperSTEM Laboratory, Keckwick Lane, Daresbury, UK
³School of Physics, Engineering and Technology, University of York, Heslington, UK
⁴Institut für Geowissenschaften, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
⁵Max Planck Institute for Chemistry, Particle Chemistry Department, Mainz, Germany
⁶Planetary Materials Group, Natural History Museum, London, UK
⁷Department of Earth Sciences, Royal Holloway, University of London, Egham, UK
⁸Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
⁹National Institutes of Natural Sciences, Institute for Molecular Science, UVSOR Synchrotron Facility, Okazaki, Japan
¹⁰School of Chemical and Process Engineering and School of Physics and Astronomy, University of Leeds, Leeds, UK

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

¹R.M. Marshal,¹M. Patzek,¹O. Rüsch
Icarus (in Press) Open Access Link to Article [https://doi.org/10.1016/j.icarus.2024.115984]
¹Institut für Planetologie, Universität Münster, 48149 Münster, Germany
Copyright Elsevier

This study investigates the key role of boulders, particularly their surface texture, which are primary surface features on small airless planetary bodies, that serve as indicators to better understand the geological history and evolutionary processes undergone by the small bodies and their respective parent bodies. In particular, this study focuses on characterizing the unpolished surface of meteorite samples, which can be likened to the surfaces of boulders on small bodies. We use surface roughness metrics such as the mean (bidirectional) slope and a Hapke mean slope angle in order to characterize the surface texture of the samples. Furthermore, considering a fractal roughness of the surface we estimate the Hurst exponent and the associated scaling factor at an arbitrary scale of ~60 μm. We find that on the ~4 μm scale, the mean bidirectional slope and the mean Hapke slope are in the range of 20–40° and 15–35° respectively, with carbonaceous chondrites collectively exhibiting the lowest average value for both. Furthermore, we provide surface roughness measurements for a subsample of the Ryugu sample A0008, which is broadly in agreement with the measurements derived from MASCam data. This study also investigated intra-sample heterogeneities, specifically surface roughness variations between matrix and non-matrix components such as impact melt, shock veins, and chondrules. The results suggest that surface roughness variations exist between these components and the matrix, however, the amplitude of the variation is strongly influenced by the petrological homogeneity of the chosen region of interest.

¹A.-M. Seydoux-Guillaume,²T. de Resseguier,³G. Montagnac,⁴S. Reynaud,⁵H. Leroux,³B. Reynard,⁶A.J. Cavosie
Earth and Planetary Science Letters 628, 118587 Link to Article [https://doi.org/10.1016/j.epsl.2024.118587]

¹UJM-Saint-Etienne, LGL-TPE UMR5276 CNRS, 42023 Saint Etienne, France
²PPRIME, CNRS-ENSMA-Université de Poitiers, 1 avenue Clément Ader, Futuroscope, 86961, France
³ENSL, UCBL, UJM, CNRS, LGL-TPE, Univ Lyon, Lyon F-69007, France
⁴UJM-Saint-Etienne, CNRS, Institut d’Optique Graduate School, Laboratoire Hubert Curien UMR 5516, Université de Lyon, Saint-Etienne F-42023, France
⁵CNRS, INRAE, Centrale Lille, UMR 8207 – UMET – Unité Matériaux et Transformations, Univ. Lille, Lille F-59000, France
⁶The Space Science and Technology Centre (SSTC) and the Institute for Geoscience Research (TIGeR), School of Earth and Planetary Science, Curtin University, Perth, WA 6102, Australia
Copyright Elsevier

Impact-related damage in minerals and rocks provides key evidence to identify impact structures, and deformation of U-Th-minerals in target rocks, such as monazite, makes possible precise dating and determination of pressure-temperature conditions for impact events. Here a laser-driven shock experiment using a high-energy laser pulse of ns-order duration was carried out on a natural monazite crystal to compare experimentally produced shock-deformation microstructures with those observed in naturally shocked monazite. Deformation microstructures from regions that may have experienced up to ∼50 GPa and 1000 °C were characterized using Raman spectroscopy and transmission electron microscopy. Experimental results were compared with nanoscale observations of deformation microstructures found in naturally shocked monazite from the Vredefort impact structure (South Africa). Raman-band broadening observed between unshocked and shocked monazite, responsible for a variation of ∼3 cm−1 in the FWHM, is interpreted to result from the competition between shock-induced distortion of the lattice, and post-shock annealing. At nanoscale, two main plastic deformation structures were found in experimentally shocked monazite: mosaïcism, and deformation bands. In contrast, the naturally shocked monazite sample, contained only deformation twins with elemental enrichment along host-twin boundaries. Both mosaicism and deformation bands, expressed in SAED patterns as streaking of spots, and the presence of extra spots (more or less pronounced), are proposed as nano-scale signatures of shock metamorphism in monazite. Experimentally calibrated deformation features, such as those documented here at TEM-scale, provide new tools for identifying evidence of shock deformation in natural samples.

¹Guido Jonker,²Flore van Maldeghem,³Matthias van Ginneken,²Lisa Krämer Ruggiu,²Steven Goderis
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14145]
¹Department of Earth Sciences, Faculty of Science, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
²Archaeology, Environmental Changes, and Geo-Chemistry, Vrije Universiteit Brussel, Brussels, Belgium
³Centre for Astrophysics and Planetary Science, School of Physical Sciences, University of Kent, Canterbury, UK
Published by arrangement

Cosmic dust particles originate from a wide variety of solar system and interstellar objects, including sources not identified among meteorite collections. Particles that survive atmospheric entry are retrieved on the Earth’s surface as micrometeorites. The recovery of these micrometeorites has recently advanced to rooftop sites. Here, we present the results of an extensive isotopic study on this type of rooftop micrometeorite from the Budel collection, the Netherlands, accreted to the Earth between October 31, 2018 and June 16, 2021. The triple oxygen isotopic compositions of 80 silica-dominated cosmic spherules (CSs) with diameters ranging between 105 and 515 μm are obtained relying on 213 in situ spot analyses determined using ion microprobe. Our analyzed population spans a large range of isotopic compositions and is dominated by carbonaceous chondritic sources. In situ measurements on several CSs support a possible continuum between 16O-rich and 16O-poor compositions following the CM mixing line, showing that 16O-poor CSs may be genetically related to aqueously altered carbonaceous chondrites. We demonstrate that weathering in the terrestrial environment has negligible effects on the isotopic compositions of the studied CSs and attempt to quantify the effects of kinetic mass-dependent fractionation and admixture of terrestrial oxygen during atmospheric entry. The results further corroborate previously suggested relations between CS texture and the duration and intensity of the heating pulse experienced during atmospheric deceleration. Finally, the young and well-constrained terrestrial age of the collection provides insights into the most recent flux of cosmic dust. Our results indicate no major recent changes in the global flux compared with collections sampled over thousand- to million-year time scales and demonstrate that 16O-poor material is still represented in the modern-day cosmic dust flux at a relative abundance of ~13%–15%. As such, rooftop micrometeorites represent a valuable reservoir to study the characteristics of the contemporary cosmic dust flux.

¹Mohammad Tauseef,¹Ingo Leya,²Jérôme Gattacceca,³Beda Hofmann,⁴Sönke Szidat,⁴Régis Braucher,⁴ASTER Team
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14144]
¹Space Research and Planetary Science, Physics Institute, University of Bern, Bern, Switzerland
²CNRS, IRD, INRAE, CEREGE, Aix Marseille Univ, Aix-en-Provence, France
³Natural History Museum Bern, Bern, Switzerland
⁴Department of Chemistry, Biochemistry and Pharmaceutical Sciences, Oeschger Center for Climate Change Research, University of Bern, Bern, Switzerland
Published by arrangement with John Wiley & Sons

We perform a systematic and detailed study of the 14C and 14C-10Be dating systems for meteorite terrestrial ages. Physical model calculations indicate that neither the 14C production rates nor the 14C/10Be production rate ratios are constant enough to be reasonably approximated by average values. By using simple averages, one introduces a significant size-dependent bias into the database for meteorite terrestrial ages. By combining modeled 14C production rates and 14C/10Be production rate ratios with (22Ne/21Ne)cos ratios and assuming ~80% ablation losses, relatively easy to use correlations of 14C production rates and 14C/10Be production rate ratios as a function of (22Ne/21Ne)cos are established. The new correlations enable the determination of terrestrial ages that are more accurate than ages based solely on average values for 14C and/or 14C/10Be. We validate the model predictions by measuring 14C activity concentrations, 14C/10Be production rate ratios, 21Necos concentrations, and (22Ne/21Ne)cos ratios in four recently fallen meteorites: Mt. Tazerzait, Boumdeid (2011), Bensour, and SaU 606. The experimental data confirmed the model predictions, although the available data are insufficient to be conclusive. More data from freshly fallen meteorites are needed for validating the model predictions for different chondrite sizes and chondrite types.

^1,2Chitrangada Datta,^1,3Yuri Amelin,^1,4,5Evgenii Krestianinov,⁶Anthony J. Irving,¹Ian S. Williams
Icarus (in Press) Open Access Link to Article [https://doi.org/10.1016/j.icarus.2024.115979]
¹Research School of Earth Sciences, The Australian National University, Canberra, ACT 2601, Australia
²School of Earth, Atmosphere & Environment, Monash University, Clayton, VIC 3168, Australia
³Korea Basic Science Institute, Ochang, Cheongwon, Cheongju, Chungbuk 28119, Republic of Korea
⁴Department of Geological Sciences, Universidad Catolica del Norte, UCN, Antofagasta, Chile
⁵Center for Excellence in Astrophysics and Associated Technologies, CATA, Santiago, Chile
⁶Department of Earth & Space Sciences, University of Washington, Seattle, WA 98195, USA
Copyright Elsevier

Pb-isotopic dating of the recently discovered diabasic angrite Northwest Africa (NWA) 12,320 yielded ages of 4564.17 ± 0.50 Ma and 4562.82 ± 0.37 Ma for acid-insoluble and soluble minerals respectively. These ages are calculated using measured 238U/235U ratios of soluble and insoluble minerals, thereby excluding the possibility that the apparent age difference is caused by internal U-isotopic variations. The age of the insoluble minerals is indistinguishable from published Pb isotopic ages of other medium-grained angrites SAH 99555 and D’Orbigny. The age of acid-soluble minerals is distinctly younger, with a 1.35 ± 0.62 Ma age gap between the Pbsingle bondPb ages of the two mineral fractions. The mineral hosts of U, Th and radiogenic Pb in the meteorite were identified through in-situ SIMS measurements of these elements in all minerals. The principal carriers of U, Th and radiogenic Pb are acid insoluble Al-Ti-rich augite and soluble Si-rich phosphate. Closure temperatures for diffusion of radiogenic Pb in these minerals are calculated to be respectively 820 ± 90 °C and 450 ± 80 °C using the observed range of crystal dimensions and the published experimental data for Pb diffusion in augite and apatite. The age difference between the pyroxene and phosphates has two potential explanations: (1) a late reheating event >450 °C which may have re-set the Usingle bondPb systematics of the phosphates but not the pyroxenes or (2) slow cooling of the rock from ~450–820 °C. If slow cooling is the reason for the age difference, we can estimate a model cooling rate of 270 ± 150 °C/Ma over the estimated closure temperature range between pyroxenes and phosphates. This rate is ~11 orders of magnitude slower than petrologic cooling rates of quenched angrites at temperatures above 1000 °C determined experimentally using the composition of Asuka 881,371 groundmass (Keil, 2012), which is similar to NWA 12320 groundmass. If there was no late reheating event, the discrepancy between fast cooling rates at high temperatures near the solidus, followed by much slower cooling at lower temperatures, might have been caused by impact melting. It could also be attributed to the initial eruption of the source magma of NWA 12320 near the surface of the parent body, followed by burial due to subsequent eruptions.

¹Merislava Anguelova,²Nicolas Vilela,³Sebastian Kommescher,^2,4Nicolas D. Greber,¹Manuela A. Fehr,¹Maria Schönbächler
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2024.01.026]
¹Institute of Geochemistry and Petrology, ETH Zurich, 8092 Zurich, Switzerland
²Institute of Geological Sciences, University of Bern, 3012 Bern, Switzerland
³Institut für Geologie, Mineralogie und Geophysik, Ruhr-Universität Bochum, 44801 Bochum, Germany
⁴Muséum d’histoire naturelle de Genève, 1208 Genève, Switzerland
Copyright Elsevier

Titanium isotopes are a promising tracer for planetary differentiation processes. The application of this tracer is, however, currently hampered by the lack of a robust estimate for the chondritic reservoir. Here, we conducted an inter-comparison Ti isotope study of three laboratories with the aim of providing an accurate and precise estimate for the chondritic reservoir. While previous estimates may suffer from heterogeneities on the sampling scale, we chose ordinary chondrites to minimise uncertainties associated with the necessary corrections for nucleosynthetic isotope variations in chondrites, and to allow the analysis of sufficiently large sample sizes representative for bulk meteorites. Titanium isotope data reported by the different laboratories are in good agreement with each other. Ordinary chondrites of different subgroups (H, L, LL) and petrologic types (3–6) display identical Ti isotope compositions within uncertainties (average δ49Ti = +0.023 ± 0.009 ‰, 2SE, n = 20; permille deviation of 49Ti/47Ti from the OL-Ti standard). The average Ti isotope composition of ordinary chondrites is within 2SE identical to that of OIBs (+0.029 ± 0.005 ‰, 2SE, n = 52) and all pre 2.7 Ga mafic and komatiitic rocks (+0.019 ± 0.006 ‰, 2SE, n = 58), indicating that the δ49Ti values of the bulk silicate Earth and ordinary chondrites are indistinguishable. Furthermore, our average Ti isotope composition of ordinary chondrites overlaps with those of the Moon, Mars and Vesta, suggesting a homogeneous inner Solar System in terms of mass-dependent Ti isotopes.

^1,2Philipp R. Heck,^1,3Birger Schmitz,¹Xenia Ritter,^1,2Surya S. Rout,⁴Noriko T. Kita,⁵Céline Defouilloy,^1,2Katarina Keating,¹Kevin Eisenstein,³Fredrik Terfelt
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14133]
¹Robert A. Pritzker Center for Meteoritics and Polar Studies, Negaunee Integrative Research Center, Field
Museum of Natural History, Chicago, Illinois, USA
²Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois, USA
³Astrogeobiology Laboratory, Department of Physics, Lund University, Lund, Sweden
⁴WiscSIMS, Department of Geoscience, University of Wisconsin, Madison, Wisconsin, USA
⁵Cameca, Gennevilliers, France
Published by arrangement with John Wiley & Sons

Extraterrestrial chrome spinel and chromite extracted from the sedimentary rock record are relicts from coarse micrometeorites and rarely meteorites. They are studied to reconstruct the paleoflux of meteorites to the Earth and the collisional history of the asteroid belt. Minor element concentrations of Ti and V, and oxygen isotopic compositions of these relict minerals were used to classify the meteorite type they stem from, and thus to determine the relative meteorite group abundances through time. While coarse sediment-dispersed extraterrestrial chrome-spinel (SEC) grains from ordinary chondrites dominate through the studied time windows in the Phanerozoic, there are exceptions: We have shown that ~467 Ma ago, 1 Ma before the breakup of the L chondrite parent body (LCPB), more than half of the largest (>63 μm diameter) grains were achondritic and originated from differentiated asteroids in contrast to ordinary chondrites which dominated the meteorite flux throughout most of the past 500 Ma. Here, we present a new data set of oxygen isotopic compositions and elemental compositions of 136 grains of a smaller size fraction (32–63 μm) in ~467 Ma old pre-LCPB limestone from the Lynna River section in western Russia, that was previously studied by elemental analysis. Our study constitutes the most comprehensive oxygen isotopic data set of sediment-dispersed extraterrestrial chrome spinel to date. We also introduce a Raman spectroscopy-based method to identify SEC grains and distinguish them from terrestrial chrome spinel with ~97% reliability. We calibrated the Raman method with the established approach using titanium and vanadium concentrations and oxygen isotopic compositions. We find that ordinary chondrites are approximately three times more abundant in the 32–63 μm fraction than achondrites. While abundances of achondrites compared to ordinary chondrites are lower in the 32–63 μm size fraction than in the >63 μm one, achondrites are approximately three times more abundant in the 32–62 μm fraction than they are in the present flux. We find that the sources of SEC grains vary for different grain sizes, mainly as a result of parent body thermal metamorphism. We conclude that the meteorite flux composition ~467 Ma ago ~1 Ma before the breakup of the LCPB was fundamentally different from today and from other time windows studied in the Phanerozoic, but that in contrast to the large size fraction ordinary chondrites dominated the flux in the small size fraction. The high abundance of ordinary chondrites in the studied samples is consistent with the findings based on coarse extraterrestrial chrome-spinel from other time windows.

¹Simone Cogliati,¹Michael C. Macey
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14141]
¹AstrobiologyOU, Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes, UK
Published by arrangement with John Wiley & Sons

To assess whether life existed on Mars, it is crucial to identify geochemical biosignatures that are relevant to specific Martian environments. In this paper, thermochemical modeling was used to investigate fluid chemistries and secondary minerals that would have evolved biotically over geological time scales in Martian fluvio-lacustrine and evaporitic settings, and that could be used as potential inorganic biosignatures for life detection on Mars. Modeling was performed using fluid and rock chemistries relevant to Gale crater aqueous environments. Potential inorganic biosignatures were identified investigating alteration deposits found at the surface of a simulant exposed to short-term bio-mediated weathering and comparing experimental and modeling results. In a fluvio-lacustrine setting (water/rock of 2000–278), models suggest that less complex mineral assemblages form during biotic basalt dissolution and subsequent brine evaporation compared to what would happen in an abiotic system. Mainly nontronite, kaolinite, and quartz form under biotic conditions, whereas celadonite, talc, and goethite would also precipitate abiotically. Quartz, sepiolite, and gypsum would precipitate from the evaporation of fluids evolved biotically, whereas nontronite, talc, zeolite, and gypsum would form in an abiotic evaporitic environment. These results could be used to distinguish products of abiotic and biotic processes, aiding the interpretation of data from Mars exploration missions.