¹Zelia Dionnet et al. (>10)
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14068]
¹CNRS, Institut d’Astrophysique Spatiale, Université Paris-Saclay, Orsay, France
Published by arrangement with John Wiley & Sons

We report μm-scale nondestructive infrared (IR) hyperspectral results (IR computed tomography, IR-CT) in 3-D and IR surface imaging, IR-S) in 2-D, at SOLEIL) combined with X-ray nano-computed tomography analyses (at SPring-8) performed on eight small Ryugu fragments extracted from mm-sized grains coming both from touchdown first and second sites. We describe the multiscale assembly of phyllosilicates, carbonates, sulfides, oxides, and organics. Two types of silicates, as well as diverse kinds of organic matter, were detected inside Ryugu material. Their spatial correlations are described to discuss the role of the mineralogical microenvironments in the formation/evolution of organic matter. In particular, we have shown that there is a redistribution of the organic matter diffuse component during aqueous alteration on the parent body, with a preferential circulation among fine-grained phyllosilicates.

^1,2Iori Kajitani,³Mizuho Koike,⁴Ryoichi Nakada,⁵Gaku Tanabe,^2,6Tomohiro Usui,⁷Fumihiro Matsu’ura,⁸Keisuke Fukushi,⁵Tetsuya Yokoyama
Earth and Planetary Science Letters 620, 118345 Link to Article [https://doi.org/10.1016/j.epsl.2023.118345]
¹Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo. 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
²Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency. 3-1-1 Yoshinodai, Sagamihara, Kanagawa 252-5210, Japan
³Earth and Planetary Systems Science Program, Department of Advanced Science and Engineering, Hiroshima University. 1-3-1 Kagamiyama, Higashihiroshima, Hiroshim 739-8526, Japan
⁴Kochi Institute for Core Sample Research, Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC). 200 Monobe, Nankoku, Kochi 783-8502, Japan
⁵Department of Earth and Planetary Sciences, School of Science, Tokyo Institute of Technology. 2-12-1 Ookayama, Meguro, Tokyo 152-8550, Japan
⁶Earth-Life Science Institute, Tokyo Institute of Technology. 2-12-1 Ookayama, Meguro, Tokyo 152-8550, Japan
⁷International Center for Isotope Effects Research, Nanjing University, Nanjing, Jiangsu Province 210023, China
⁸Institute of Nature and Environmental Technology, Kanazawa University, Kanazawa, Ishikawa, Japan
Copyright Elsevier

The aqueous environment and possible habitability of early Mars have been widely studied based on orbital and in situ explorations, as well as analyses of Martian meteorites. Using microscale X-ray absorption near edge structure (μ-XANES) analysis, we report the first sulfur (S) speciation of the carbonates in a Martian meteorite, Allan Hills 84001, precipitated in the 4-billion-year-old aqueous alteration on Mars. The XANES data show diagnostic signatures of oxidized sulfur in the carbonates, indicating that carbonate-associated sulfate (CAS) formed from coexisting sulfate ions (SO
) in the aqueous fluid. A thermodynamic calculation suggests that the CAS deposited from a fluid with a moderately oxidizing to reducing and neutral to slightly alkaline pH condition. The possible sources of SO
ions are the minor SOx species in the Noachian atmosphere and/or the supply from volcanic gas. It is concluded that considerable amounts of the atmospheric volatiles including CO2 and SOx may have been stored as alteration products (e.g., carbonates) in the Martian underground system.

^1,2Andrea Patzer,¹Emma S. Bullock,¹Conel M. O’D. Alexander
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2023.08.021]
¹Earth and Planets Laboratory, Carnegie Institution for Science, 5241 Broad Branch Rd. NW, Washington D.C. 20015, USA
²Geosciences Center, University of Göttingen, Goldschmidtstr. 1, 37077 Göttingen, Germany
Copyright Elsevier

In continuation of our comprehensive study of the carbonaceous chondrites, we here present data for the CM chondrites. Our study’s aim is to determine the abundances and the average elemental compositions of the major and minor chondritic components. The overarching goal has been to explore the fundamental question of whether chondrules and matrix are complementary, i.e., genetically related, or if these major chondritic components evolved separately before accretion as in the four-component model.

Using point-counting and electron microprobe analyses, we investigated the most primitive CMs known to date: Asuka (A) 12169 (CM3.0), A 12236 (CM2.9) and Paris (CM2.7-2.9). Despite their primitiveness, however, none of the samples is completely devoid of signs of terrestrial and/or parent body alteration. For instance, we found evidence for the mobilization and heterogenous redistribution of Ca, as well as for the leaching of Al from chondrules and redeposition into matrix. There is also a trend of the Ca and Al abundances in both, chondrules and matrix, to become increasingly heterogeneous with increasing parent body alteration. We were, therefore, unable to test chondrule-matrix complementarity and the four-component model using Al and Ca. Assuming that Mg and Si are insignificantly affected by alteration and that the Mg/Si ratios of the components in A 12169 are unaltered, our data indicate the pre-accretionary loss from matrix of ∼12 wt.% forsterite (matching our results for the primitive COs and CRs) and the addition of a roughly similar amount of forsterite to the chondrules (contrary to our results for the COs and CRs). These results are inconsistent with the four-component model but, based on the matrix/chondrule abundance ratio, complementarity predicts that the addition of forsterite to chondrules should have been significantly higher. This and the possibility that A 12169 component compositions have been modified to some degree means that our results do not unambiguously favor either model.

Cosmochemistry Papers will be on Summer Break for the nex week. We will commence operations again on September, 1st.

¹R. G. Mayne,¹L. Caves,²T. J. McCoy,³R. D. Ash,³W. F. McDonough
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14031]
¹Monnig Meteorite Collection and Gallery, College of Science and Engineering, Texas Christian University, Fort Worth, Texas, USA
²Department of Mineral Sciences, National Museum of Natural History, Smithsonian Institution, Washington, District of Columbia, USA
³Department of Geology, University of Maryland, College Park, Maryland, USA
Published by arrangement with John Wiley & Sons

Mesosiderites are an amalgamation of crustal silicates and molten metal, and their formational history is not well understood. It is widely believed that redox reactions occurred in the mesosiderites during metal–silicate mixing. Previous studies evaluated redox reactions by studying the silicates within mesosiderites, but little attention has been given to the metal for complementary evidence of such processes. Here, the evidence for redox within the metal portion of five mesosiderites is documented, most notably lower P content in the matrix metal relative to clast metal (nodule). These observations, together with the noted FeO reduction in silicates, provide further support for redox reactions occurring during metal–silicate mixing. Samples with differing Ir concentrations, such as Chaunskij and RKP A70015, have been previously classified as anomalous. However, the marked variation in highly siderophile element concentrations in all of these mesosiderites is consistent with fractional crystallization. These compositional trends could be explained by isolated metallic masses that underwent fractional crystallization before mixing or by hit-and-run collisions that produced metallic masses that ranged in size.

¹Miriam Rüfenacht,¹Précillia Morino,^1,2Yi-Jen Lai,¹Manuela A. Fehr,^1,3Makiko K. Haba,¹Maria Schönbächler
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2023.06.005]
¹Institute of Geochemistry and Petrology, ETH Zurich, Clausiusstrasse 25, CH-8092 Zurich, Switzerland
²Macquarie GeoAnalytical, Faculty of Science and Engineering, Macquarie University, Sydney 2109, NSW, Australia
³Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Ishikawadai Building 2-105, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan
Copyright Elsevier

Nucleosynthetic isotope variations are powerful tools to investigate genetic relationships between meteorite groups and planets. They are instrumental to assess the early evolution of the solar system, including mixing and reservoir formation in the protoplanetary disk, as well as planet formation. To address these questions, we report high-precision nucleosynthetic Ti isotope compositions of a wide range of bulk meteorites, partially complemented with new Cr isotope data. New Ti isotope data confirm the first order dichotomy observed between carbonaceous chondrites (CC), representing outer solar system compositions, and non-carbonaceous (NC) meteorites from the inner solar system. The data in combination with nucleosynthetic isotope data of other elements (e.g., Cr, Ca) indicate that isotopically heterogeneous reservoirs were also present as sub-reservoirs in the inner disk (NC reservoir), generating two or more clusters i.e., (i) the Vesta-like howardites-eucrites-diogenites (HEDs), mesosiderites, angrites, acapulcoites, lodranites, and brachinites and (ii) the Earth-Mars-like ordinary chondrites (OC), aubrites, enstatite chondrites (EC), winonaites, IAB silicates, rumuruti chondrites (R), Martian and terrestrial samples. These reservoirs likely represent disk substructures such as secondary gaps and ring-structures, created by spiral arms, which were emitted from the growing Jupiter and/or Saturn. The distinct isotopic compositions of these reservoirs may reflect thermal processing of material within the disk in combination with temporal isotopic variations either due to isotopically variable infalling material from a heterogeneous molecular cloud and/or thermal processing during the infall that induced such heterogeneities. Such effects were likely reinforced by thermal processing of the material within the disk itself and by physical size- and density sorting of dust caused by the giant planets, creating gaps and pressure bumps in the disk.

Genetic relationships of meteorite groups and their implications on parent body formation are evaluated. New high precision Ti isotope data are consistent with that (i) CH and CB meteorites derive from a common parent body, which most likely accreted material from the same isotopic reservoir as the parent body of CR chondrites, (ii) silicates of IAB irons and winonaites originate from the same parent body, and (iii) mesosiderites and HED meteorites have a common origin on Vesta. The indistinguishable Ti and Cr isotope compositions of HEDs/mesosiderites to acapulcoites are not attributed to a common parent body, because of petrologic and chemical differences in addition to their distinct O isotope compositions. Their parent bodies likely accreted in the same disk region, which showed a higher level of O isotope heterogeneity compared to that of Ti, Cr and other refractory nucleosynthetic tracers. The similarity in Ti isotope compositions of Martian meteorites and OCs indicates that OC-like material belongs to the main building blocks of Mars.

¹Yan Hu,¹Frédéric Moynier,^2,3Xin Yang
Earth and Planetary Science Letters 620, 118319 Link to Article [https://doi.org/10.1016/j.epsl.2023.118319]
¹Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, UMR 7154, Paris 75005, France
²Department of the Geophysical Sciences, The University of Chicago, Chicago, IL 60637, USA
³Robert A. Pritzker Center for Meteoritics and Polar Studies, Negaunee Integrative Research Center, Field Museum of Natural History, Chicago, IL, USA
Copyright Elsevier

The stable potassium isotopic ratios (41K/39K) of Earth and Mars have been interpreted to reflect either nucleosynthetic isotope anomalies or volatility-driven K depletion. Chondrites comprise primordial materials from which planetary bodies are assembled, and thus are critical samples for this discussion. Here, we present high-precision K isotopic analyses (reported as
K) of 33 chondrites and two achondrites, which reveal unprecedented variation from −1.08 to 4.68‰. In addition, there is considerable overlap in
K values between carbonaceous and non-carbonaceous meteorites despite their contrasting nucleosynthetic isotope anomalies. These findings are inconsistent with the nucleosynthetic origin of 41K variations in meteorites. Instead, the
K values of chondrites correlate positively with the isotopic compositions of other moderately volatile elements (e.g., Rb, Cu, Zn, Sn, Ga, and Te). These correlations suggest that volatility-controlled fractionation is a common mechanism for mass-dependent isotopic variations in the Solar System. In particular, carbonaceous chondrites and the angrite parent body exhibit a trend of concomitant decreases in K and its heavier isotope due to incomplete K condensation. Earth and Mars also follow this trend, suggesting that their K depletion may reflect similar volatile-depleting processes that occurred with their respective precursors. That Mars is isotopically heavier than Earth is consistent with it having less K-depleted precursors, in addition to the previous suggestion of a later-stage K loss from proto-Mars during accretionary collisions.

¹Qin Zhou et al. (>10)
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2023.08.017]
¹Key Laboratory of Lunar and Deep Space Exploration, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, China
Copyright Elsevier

The U(Pb)-Pb age of zircon is commonly used to represent the crystallization age for igneous rocks due to its high closure temperature and robust resistance to impact disturbance. However, no zircon crystallization age has yet been reported for Chang’e-5 (CE-5) basalt due to their limited occurrence in mare basalt. In this study, rare zircon grains from CE-5 lunar samples were investigated by the in-situ Pb isotopic analysis, and a precise zircon crystallization age of 2036 ± 19 Ma was determined from Pb-Pb isochron. This is hitherto the youngest reported crystallization age of lunar zircon, similar to the ages of CE-5 lunar basalts obtained by zirconium (Zr)-bearing minerals such as baddeleyite, tranquillityite, and zirconolite. Petrographic evidence and rare-earth element geochemistry indicate that zircon in the CE-5 lunar basalts were formed by the reaction of early-formed baddeleyite with SiO2 melt within the latest residue of extreme fractionation of a non-KREEP (an acronym for potassium, REE, and phosphorus) basaltic magma. In contrast to the prevailing view that lunar zircon have formed in late-stage enriched melts resulting from extensive fractional crystallization of the Lunar Magma Ocean, this study shows that zircon could be derived from extreme fractionation of non-KREEP basaltic magma unrelated to Lunar Magma Ocean.

^1,2Akaogi, Masaki, ¹Miyazaki, Natsuki,¹Tajima, Taisuke,¹Kojitani, Hiroshi
Physics and Chemistry of Minerals 50, 23 Link to Article [DOI 10.1007/s00269-023-01247-4]
¹Department of Chemistry, Gakushuin University, Mejiro, Toshima-ku, Tokyo, 171-8588, Japan
²Geochemical Research Center, Graduate School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan

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

¹Ali Ettehadi,¹Mehdi Mokhtari,¹Maksym Chuprin,²Robert C. Anderson,³Gursat Altun,⁴Ezat Heydari
Icarus (in Press) Link to Article[https://doi.org/10.1016/j.icarus.2023.115760]
¹University of Louisiana at Lafayette, Louisiana, USA
²Jet Propulsion Laboratory (JPL), California, USA
³Istanbul Technical University, Istanbul, Turkey
⁴Jackson State University, MS, USA
Copyright Elsevier

The MSL (Mars Science Lab) Curiosity rover has documented the presence of natural fractures at the Gale crater on Mars. Through the utilization of the ChemCam instrument, the chemical composition of the veins on Mars has been analyzed, revealing their mineralogy as calcium sulfate. However, there is limited knowledge regarding the mechanical properties of these veins, which hinders a deeper understanding of their origin. This work aims to characterize the mechanical properties of gypsiferous Triassic Moenkopi mudrocks as the terrestrial rock analog to Mars. The Digital Image Correlation (DIC) technique was used in tandem with the Indirect Tensile Strength test to acquire the required spatial full-field strain maps for characterizing the fracture propagation with complex geometries in addition to the derived mechanical properties. The effect of the primary vein orientation on the exerted load on the load-strain profile, fracture initiation and propagation, and tensile strength was established. The dynamic spatial horizontal, vertical, and shear strains’ progression was distinguished through DIC imaging. The key findings include: (1) Different failure modes were observed in samples with and without calcium sulfate veins, with higher tensile strength perpendicular to lamination; (2) Most samples with veins exhibited reduced tensile strength, except when oriented 90° to the load; (3) Fracture paths were influenced by the orientation angle, with irregular paths at certain angles and more regular paths for centrally located veins; (4) Digital image correlation revealed a fracture process zone before macro-crack initiation and subsequent shear crack propagation; (5) Shear strain accumulation preceded shear crack propagation, with potential initiation of tensile cracks.