¹Helen Grant,¹Romain Tartèse,¹Rhian Jones,²Laurette Piani,²Yves Marrocchi,³Ashley King,²Thomas Rigaudier
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14041]
¹Department of Earth and Environmental Sciences, The University of Manchester, Manchester, UK
²CNRS, CRPG, UMR 7358, Université de Lorraine, Vandoeuvre les Nancy, France
³Planetary Materials Group, Natural History Museum, London, UK
Published by arrangement with John Wiley & Sons

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.

¹Rider-Stokes B.G. et al. (>10)
Nature Astronomy (in Press) Link to Article [DOI 10.1038/s41550-023-01968-0]
¹School of Physical Sciences, The Open University, Milton Keynes, United Kingdom

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¹Rochette, Pierre et al. (>10)
Comptes Rendus – Geoscience 355, 145-155 Open Access Link to Article [DOI 10.5802/crgeos.206]
¹Aix-Marseille Univ, CNRS, IRD, INRAE, UM 34 CEREGE, Aix-en-Provence, France

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¹Tadeusz A. Przylibski,²Magdalena Długosz-Lisiecka,¹Katarzyna Łuszczek,¹Konrad Blutstein
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14050]
¹Faculty of Geoengineering, Mining and Geology, Wrocław University of Science and Technology, Wrocław, Poland
²Institute of Applied Radiation Chemistry, Łódź University of Technology, Łódź, Poland
Published by arrangement with John Wiley & Sons

We used two different methods of statistical analysis—cluster analysis and principal component analysis—to analyze the concentrations of principal chemical components (Si, Mg, Ca, Fe, Ni) and Co in ordinary chondrites. The analysis is based predominantly on published data (metadata). In total, chemical composition data from 646 ordinary chondrites were used in the statistical analysis. The aim of this analysis was to establish whether it would be possible or not to distinguish H, L, and LL chondrites based on the concentrations of major elements and Co in their bulk chemical compositions. It was also important to determine what conclusions such an analysis could enable to draw about matter differentiation in the formation environments of primordial parent bodies of particular ordinary chondrite groups (H, L, and LL). Another aim of the statistical analysis was to determine whether the distribution of Fe and Ni (with Co admixtures) is independent of petrographic types within particular groups of chondrites. This is of crucial importance for determining the distribution of FeNi(Co) ore occurrences in potential extraterrestrial deposits on modern asteroids—the sources of ordinary chondrites. The obtained results of statistical analyses confirmed that a clear-cut distinction between particular groups of ordinary chondrites is only possible for group H, while distinguishing L chondrites from LL chondrites is not always obvious. The results of the statistical analyses relating to the question of the possible existence of several primordial parent bodies (formation environments) of each group of ordinary chondrites are consistent with the results of contemporary astronomical spectroscopy research. What is particularly interesting is obtaining indications of the existence of common formation environments of the matter of L and LL chondrites, possibly on a few primordial parent bodies. The statistical analyses indicate that there is no correlation between the concentration of principal chemical components and the petrographic type of ordinary chondrites. This proves homogenous distributions of these elements within the parent bodies of each group of ordinary chondrites. Hence, the distribution of these elements in individual present-day asteroids is also homogenous.

¹Addi Bischoff,^1,2Mike Komnik,¹Jakob Storz,³Jasper Berndt
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14052]
¹Institut für Planetologie, University of Münster, Münster, Germany
²Institut für Geologie und Paläontologie, University of Münster, Münster, Germany
³Institut für Mineralogie, University of Münster, Münster, Germany
Published by arrangement with John Wiley & Sons

The lunar regolith breccia Dhofar 1769, which was found in 2012 as a single 125 g piece in the Zufar desert area of Oman, contains a relatively large, dark-colored impact melt breccia embedded in a fine-grained clastic matrix. The internal texture of the fragment indicates the repeated melt breccia formation on the lunar surface, their repeated brecciation, and mixing in second, third, and fourth generations of brecciated rock types. The chemical and mineralogical data reveal the incorporation of a feldspar-rich subophitic crystalline melt within a feldspar-rich microporphyritic crystalline melt breccia. This lithic paragenesis itself is embedded within a mafic, crystalline melt breccia. The entire breccia with the three different impact melts has been finally incorporated into the whole rock breccia. The three impact melts are mixtures of different source rocks and impact projectiles, based on the obtained minor and trace element compositions (in particular of Ni and the rare earth elements [REE]) of the impact melt lithologies. For all processes of impact melt formation, additional steps of their brecciation and re-lithification require a minimum number of seven impact processes.

¹Mazumdar, Amulya Chandra,^2,3Pati, Jayanta Kumar,²Singh, Anuj Kumar,¹Bhagabaty, Balen,¹Phukan, Sarat,¹Borah, Pritom
Geological Journal (in Press) Link to Article [DOI 10.1002/gj.4776]
¹Department of Geological Sciences, Gauhati University, Guwahati, India
²Department of Earth and Planetary Sciences, Nehru Science Centre, University of Allahabad, Prayagraj, India
³National Centre of Experimental Mineralogy and Petrology, University of Allahabad, Prayagraj, India

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¹Savina, Michael R.,¹Shulaker, Danielle Ziva,¹Isselhardt, Brett H.,¹Brennecka, Gregory A.
Journal of Analytical Atomic Spectrometry 38, 1205-1212 Open Access Link to Article [DOI
10.1039/d3ja00096f]
¹Lawrence Livermore National Laboratory, Nuclear and Chemical Sciences Division, United States

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¹R. Keerthana,¹R. Annadurai,²K.N. Kusuma
Planetary and Space Science (in Press) Link to Article [https://www.sciencedirect.com/science/article/abs/pii/S0032063323001150]

¹Department of Civil Engineering, SRM Institute of Science and Technology, Kattankulathur, 603 203, India
²Department of Earth Sciences, Pondicherry University, Puducherry, 605 014, India

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^1,2Marina Martínez,^1,3Charles K. Shearer,¹Adrian J. Brearley
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14042]
¹Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico, USA
²Universitat Autònoma de Barcelona, Edifici Cs, Av. de l’Eix Central, s/n, 08193 Cerdanyola del Vallès, Barcelona,
Spain.
³Institute of Meteoritics, University of New Mexico, Albuquerque, New Mexico, USA
Copyright Elsevier

Secondary minerals in martian nakhlites provide a powerful tool for investigating the nature, composition, and duration of aqueous activity in the martian crust. Northwest Africa (NWA) 998 crystallized early from the nakhlite magmatic source and has evidence of minimal signatures of the late hydrothermal alteration event that altered the nakhlites. Using FIB-TEM techniques to study a cumulus apatite grain in NWA 998, we report the first evidence of a submicron-scale vein consisting of fluorapatite and an SiO2-rich phase. Fluorapatite grew epitaxially on the walls of an opened cleavage plane of host F-bearing chlorapatite and the SiO2-rich phase filled the center of the vein. The presence of nanoporosity and nanometer-scale amorphous material and the sharp interface between the vein and the host apatite indicate the vein represents a coupled dissolution–reprecipitation process that generated apatite of a different composition that was more stable with the fluid. Using experimental data and diffusion coefficients of Cl in apatite from the literature, we conclude that the vein was caused by a low temperature (~300°C), slightly acidic, F-, Si-rich, aqueous fluid that acted as a closed system. Based on the characteristics of the vein (formation by rapid injection of fluid) and the fluid (composition, temperature, pH), and the lack of terrestrial weathering products in our SEM and TEM images, we infer that the vein is pre-terrestrial in origin. Our observations support the hypothesis that the heat source triggering a hydrothermal system was a low-shock velocity impact and rule out a magmatic origin. Finally, the vein could have formed from a late-stage fluid different from that reported in other nakhlites, but formation during the same magmatic event by, for example, a less evolved fluid might also be plausible.

¹H. C. Bates,¹A. J. King,²K. S. Shirley,³E. Bonsall,³C. Schröder,⁴F. Wombacher,⁵T. Fockenberg,¹R. J. Curtis,¹N. E. Bowles
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14043]
¹Planetary Materials Group, Natural History Museum, London, UK
²Atmospheric, Oceanic and Planetary Physics, University of Oxford, Oxford, UK
³Biological and Environmental Sciences, Faculty of Natural Sciences, University of Stirling, Stirling, UK
⁴Institut für Geologie und Mineralogie, Universität zu Köln, Köln, Germany
⁵Institut für Geologie, Mineralogie und Geophysik, Ruhr-Universität Bochum, Bochum, Germany
Published by arrangement with John Wiley & Sons

On the microscale, the Winchcombe CM carbonaceous chondrite contains a number of lithological units with a variety of degrees of aqueous alteration. However, an understanding of the average hydration state is useful when comparing to other meteorites and remote observations of airless bodies. We report correlated bulk analyses on multiple subsamples of the Winchcombe meteorite, determining an average phyllosilicate fraction petrologic type of 1.2 and an average water content of 11.9 wt%. We show the elemental composition and distribution of iron and iron oxidation state are consistent with measurements from other CM chondrites; however, Winchcombe shows a low Hg concentration of 58.1 ± 0.5 ng g⁻¹. We demonstrate that infrared reflectance spectra of Winchcombe are consistent with its bulk modal mineralogy, and comparable to other CM chondrites with similar average petrologic types. Finally, we also evaluate whether spectral parameters can estimate H/Si ratios and water abundances, finding generally spectral parameters underestimate water abundance compared to measured values.