¹Maximilian P. Reitze,^1,2Christian Renggli,¹Andreas Morlok,¹Iris Weber,³Uta Rodehorst,¹Jasper Berndt,¹Stephan Klemme,¹Harald Hiesinger
Journal of Geophysical Research (Planets) (in Press) Open Access Link to Article [https://doi.org/10.1029/2024JE008483]
¹Universität Münster, Institut für Planetologie, Münster, Germany
²Max Planck Institute for Solar System Research, Göttingen, Germany
³MEET – Münster Electrochemical Energy Technology, Münster, Germany
Published by arrangement with John Wiley & Sons

We synthesized the solid solution between the sulfides CaS (oldhamite) and MgS (niningerite). Electron microprobe and X-ray diffraction showed homogeneous and pure samples after the synthesis. The calculated lattice parameters fit to earlier literature data. Mid-infrared spectroscopy of the samples reveal that the produced sulfides were fragile and tend to alternate very fast. However, we were able to provide clean reflectance spectra of all samples. The spectra of un-altered samples show no peaks or bands but a rather constant spectrum within the analyzed spectral range between 7.0 and 12.5 μm. The altered spectra contain signatures of sulfates and carbonates and probably further compounds. The gathered data help to understand the formation conditions of the studies sulfides as it shows that the solvus exists in the CaS-MgS system between 1000°C and 1200°C. In addition, the infrared data will help to improve remote sensing in the mid-infrared of planetary objects that might be covered with sulfide containing material like asteroids or Mercury.

^1,2C. P. Haupt,^1,3C. J. Renggli,¹A. Rohrbach,¹J. Berndt,¹S. Klemme
Journal of Geophysical Research (Planets) (in Press) Open Access Link to Article [https://doi.org/10.1029/2023JE008239]
¹Institut für Mineralogie, Universität Münster, Münster, Germany
²CNRS, Université d’Orléans, Orléans, France
³Max-Planck-Institute for Solar System Research, Göttingen, Germany
Published by arrangement with Johhn Wiley & Sons

High-pressure and high-temperature experiments were conducted to simulate melting of a hybrid cumulate lunar mantle. The experimental results show that intermediate to high-Ti lunar pyroclastic glasses (>6 wt% TiO2) can be produced by partial melting of lunar cumulates. High-Ti basalts are generated when the ilmenite/clinopyroxene ratios in the lunar mantle cumulates are between 1/1 and 4/1, depending on the degree of melting. The presence of an urKREEP component in the mantle cumulate strongly influences Al2O3/CaO of the melts. The experiments provide strong evidence for the model that the compositional diversity of lunar basalts is a consequence of a gravitational overturn of the lunar interior after the lunar magma ocean had solidified. Ilmenite/clinopyroxene in the cumulate mantle, which generates high-Ti melts at partial melting, do not comprise the ratios in ilmenite-bearing cumulates (IBC), which crystallized after ∼90% solidification of the lunar magma ocean and indicate local accumulation of ilmenite in the overturned lunar mantle. However, to fully match the natural composition of the most primitive lunar samples, secondary processes such as assimilation are still required.

^1,2Shurui Chen et al. (>10)Coline Serra^a, Vassilissa Vinogradoff^a, Grégoire Danger^a,b, Marie-Vanessa Coulet^c, Fabrice Duvernay^a
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2024.116273]
^aAix-Marseille University, Institut Origines, UMR CNRS 7345, PIIM, Marseille, France
^bbInstitut Universitaire de France, France
^cAix-Marseille University, UMR CNRS 7246, Madirel, Marseille, France
Copyright Elsevier

The presence of organic matter in carbonaceous chondrites provides valuable information about the early composition of the Solar System. Although they are considered primitive, the majority of these chondrites have undergone secondary processes subsequent to their formation. These processes, such as aqueous alteration, have altered their composition. The effect of aqueous alteration on minerals is well known, but the effect on organic matter and/or on an organo-mineral system have been little studied. Here, we report experimental results devoted to investigate the chemical evolution of a hypothetical initial chondritic material subjected to hydrothermal alteration under reducing conditions at low-temperature. The mixtures consist of different anhydrous minerals (peridot, feldspar, troilite) together with hexamethylenetetramine (HMT) chosen as a model molecule inherited from the interstellar grains. After different times at 80 °C, the large molecular diversity formed is highly influenced by the presence and the nature of the minerals, as highlighted in particular by the evolution of the amide produced. The presence of minerals in the mixture appears to influence the reactivity of the system more through the formation of salts and chelates than through surface adsorption mechanisms. The most pronounced effect is observed in the presence of troilite, both in the degradation of HMT and in the abundance of amides formed. The study of the mutual influence of minerals and organic matter, and their intrinsic transformations in the media during the processes, could help to understand about the origin of organic molecules observed in carbonaceous chondrites.

¹Vadawale, S.V. et al.(>10)
Nature 2024 Link to Article [DOI https://doi.org/10.1038/s41586-024-07870-y]
¹Physical Research Laboratory (PRL), Ahmedabad, India.

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

¹Yue Zhang, ^1,2,3Hejiu Hui, ³Sen Hu, ³Jialong Hao, ³Ruiying Li,³Wei Yang, ⁴Qiuli Li, ³Yangting Lin, ⁴Xianhua Li, ⁴Fuyuan Wu
Earth and Planetary Science Letters 644, 118933 Link to Article [https://doi.org/10.1016/j.epsl.2024.118933]
¹State Key Laboratory for Mineral Deposits Research & Lunar and Planetary Science Institute, School of the Earth Sciences and Engineering, Nanjing University, Nanjing, Jiangsu 210023, PR China
²CAS Center for Excellence in Comparative Planetology, Hefei, Anhui 230036, PR China
³Key Laboratory of the Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, PR China
⁴State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, PR China
Copyright Elevier

Lunar materials have recorded a very large δ37Cl variation, and the mechanism causing this variation has yet to be determined. We measured the F and Cl contents and the δ37Cl in Chang’e-5 impact glass beads using a nanoscale secondary ion mass spectrometry. These glass beads exhibit the largest δ37Cl variation observed to date, ranging from –0.7 ‰ to 119 ‰. Furthermore, the δ37Cl values are roughly negatively correlated with the Cl concentration. The correlations between F and Cl concentrations differ for homogeneous and heterogeneous glass beads. Our calculations indicate that NaCl (g) and HCl (g) degassing may have been the pivotal mechanism that elevated the δ37Cl value, with >50 % of Cl in the melt evaporating during glass formation. The glass beads may have incorporated the chlorine species condensed from early evaporation. Our results provide direct evidence to constrain the impact-induced degassing process of Cl on airless celestial bodies.

^1.2Ming-Chang Liu,²Nozomi Matsuda, ²Kevin D. McKeegan, ^1,2Emilie T. Dunham, ^1,2Kaitlyn A. McCain
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2024.08.015]
¹Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, 7000 East Avenue (L-231), Livermore, CA 94550, USA
²Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095, USA
Copyright Elsevier

Chemical and isotopic measurements of HIDALGO, a stoichiometrically pure hibonite inclusion found in the matrix of the Dar al Gani 027 meteorite, were conducted by secondary ion mass spectrometry to investigate its origin and evolution. HIDALGO is characterized by large mass-dependent isotope fractionations in O, Ca, and Ti, as well as large negative anomalies in neutron-rich ⁴⁸Ca and ⁵⁰Ti, making it the newest member of the HAL-type FUN inclusions. The highly fractionated Ca and Ti isotopes but unfractionated Mg isotopes are consistent with HIDALGO being a residue from an extensive evaporation event, during which large fractions of initial Ca and Ti, and essentially all the initial Mg, in the precursor material were lost. HIDALGO appears to have incorporated live ²⁶Al at a higher level than other HAL-type inclusions, but still at a lower amount compared to the Solar System’s initial ²⁶Al abundance typically found in non-FUN CAIs. Interestingly, the inferred ¹⁰Be abundance in HIDALGO is comparable to the values observed in the majority of CV3 CAIs but ∼ 2.5 times higher than those in HAL-type samples. HIDALGO’s unusual ²⁶Al/²⁷Al and ¹⁰Be/⁹Be ratios, together with the ⁴⁸Ca-⁵⁰Ti anomalies, can be best explained by the formation of its precursor material in the isotopically heterogeneous solar nebula. Finally, large ⁷Li excesses correlating with Be/Li were found in HIDALGO, a behavior that can be interpreted as due to in-situ decay of live ⁷Be. Charged particle spallation of initially Li-free HIDALGO can simultaneously account for the inferred ⁷Be abundance and the measured Li elemental concentration. The consistency between the measurement and spallation calculation results provides support for the prior existence of ⁷Be in HIDALGO, possibly produced by irradiation close to the Sun

¹Shingo Sugawara, ¹Wataru Fujiya, ²Noriyuki Kawasaki, ³Naoya Sakamoto, ⁴Akira Yamaguchi, ²Hisayoshi Yurimoto
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2024.08.013]
¹Faculty of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan
²Department of Natural History Sciences, Hokkaido University, Sapporo 060-0810, Japan
³Isotope Imaging Laboratory, Creative Research Institution, Hokkaido University, Sapporo 001-0021, Japan
⁴National Institute of Polar Research, Midoricho10-3, Tachikawa, Tokyo 190-8518, Japan
Copyright Elsevier

Aqueous alteration in planetesimals is one of the earliest geological processes in the solar system. The timing of aqueous alteration sheds light on the timescale of material evolution through water–rock interaction in small bodies. The 53Mn-53Cr decay system, where a short-lived radionuclide 53Mn decays to 53Cr with a half-life of 3.7 Myr, is a powerful tool for dating carbonates in primitive meteorites that formed during aqueous alteration. In CI chondrites and samples returned from asteroid Ryugu, a major carbonate mineral is dolomite (CaMg(CO3)2) and could be dated precisely because of their relatively high Mn abundances. However, the lack of a proper dolomite standard for secondary ion mass spectrometry (SIMS) hinders us from obtaining accurate Mn/Cr ratios of carbonates, resulting in erroneous formation ages. In this work, we synthesized Mn-, Cr-, and Fe-bearing crystalline dolomite as standard materials, and evaluated the relative sensitivity factor (RSF) of Mn/Cr for SIMS analysis, namely, the ratio of Mn/Cr obtained using SIMS to true Mn/Cr. We found that the RSF values of the dolomite standards range from 0.8 to 0.9, slightly higher than that of calcite (CaCO3) (∼0.7), and increase with their Fe contents. We used the newly evaluated RSF values to date dolomite in the Ivuna CI chondrite and obtained an initial 53Mn/55Mn ratio of (3.95 ± 0.49) × 10−6 (95 % confidence interval) and the corresponding absolute age of 4564.0 + 0.6/−0.7 Ma. Our new initial 53Mn/55Mn ratio is 26 ± 19 % higher than that obtained by a previous study for the same dolomite grain using a calcite standard. This difference is consistent with the difference between the RSF values of dolomite and calcite. Based on these results, we updated the initial 53Mn/55Mn ratio previously reported for dolomite in the Ryugu sample A0058 to be (3.21 ± 0.66) × 10−6, which corresponds to an absolute age of 4562.8 + 1.0/−1.2 Ma. This age seems to be the best estimate for the formation age of dolomite in Ryugu currently available.

¹David W. Mittlefehldt
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2024.08.010]
¹Lunar and Planetary Institute, Universities Space Research Association, 3600 Bay Area Boulevard, Houston, TX 77058, USA
Copyright Elsevier

I have done major element analyses by electron microprobe, in-situ trace element analyses by laser ablation inductively coupled plasma mass spectrometry, and instrumental neutron activation analyses on bulk samples of olivine grains separated from main-group and Eagle-Station pallasites. Most main-group pallasite olivines have homogeneous Fe/Mg yet have varying Fe/Mn. Those few with anomalously ferroan olivine have Fe/Mn within the range of other main-group pallasites. High-temperature redox process coupled with diffusional exchange resulted in the homogeneous compositions of most main-group pallasites; simple diffusional exchange alone is insufficient. The Eagle-Station pallasites have Fe/Mn twice that of main-group pallasites with similar Fe/Mg, a result of having roughly half the Mn content. The Ni/Co ratio of main-group pallasite olivines is relatively constant and was imposed by the same high-temperature redox/diffusion process that established Fe/Mg-Fe/Mn relationships. Variability in trace lithophile element contents within individual pallasites and within individual olivine grains, coupled with very low contents for some that are inconsistent with formation from a magma, indicate that the current mm-sized olivine grains were recrystallized from a fragmental olivine breccia; grain fragments from different portions of an original dunitic mantle were juxtaposed in the breccia. Main-group pallasites are dimict breccias formed of fragmented and mixed monomict dunite breccia and metallic breccia that were formed in the walls and floor of a large basin that penetrated the mantle of their parent asteroid. Limited data indicate that Eagle-Station pallasites may have been formed by a similar process. Given that Eagle-Station and main-group pallasites were formed in distinct regions of the early Solar System, the pallasite forming process likely was common in early Solar System history.

¹Mario Fischer-Gödde et al.(>10)
Science 385, 752-756 Link to Article [DOI: 10.1126/science.adk4868]
¹Institut für Geologie und Mineralogie, University of Cologne, 50674 Cologne, Germany.
Reprinted with permission from AAAS

An impact at Chicxulub, Mexico, occurred 66 million years ago, producing a global stratigraphic layer that marks the boundary between the Cretaceous and Paleogene eras. That layer contains elevated concentrations of platinum-group elements, including ruthenium. We measured ruthenium isotopes in samples taken from three Cretaceous-Paleogene boundary sites, five other impacts that occurred between 36 million to 470 million years ago, and ancient 3.5-billion- to 3.2-billion-year-old impact spherule layers. Our data indicate that the Chicxulub impactor was a carbonaceous-type asteroid, which had formed beyond the orbit of Jupiter. The five other impact structures have isotopic signatures that are more consistent with siliceous-type asteroids, which formed closer to the Sun. The ancient spherule layer samples are consistent with impacts of carbonaceous-type asteroids during Earth’s final stages of accretion.

¹Z. Váci,²P.M. Kruttasch,¹M.J. Krawczynski,³R.C. Oglior,²K. Mezger
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2024.08.011]
¹Department of Earth and Planetary Sciences, Washington University in St. Louis, MO, USA
²Institut für Geologie, Universität Bern, Switzerland
³Department of Physics, Washington University in St. Louis, MO, USA
Copyright Elsevier

The ungrouped dunitic achondrite Northwest Africa (NWA) 12,217 contains symplectic spinel-pyroxene veins that are mineralogically identical to symplectites in other ultramafic planetary materials. The morphology and amount of chromite present in these features relative to the Cr in their olivine hosts suggest an exogenous origin. Petrological experiments show that a Cr laden sulfide liquid reacts with olivine to produce pyroxene by scavenging Mg and Fe from olivine to crystallize chromite. The liquid infiltrates cracks and grain boundaries within the olivine and produces a vein-like symplectic chromite-pyroxene mineralogy similar to that observed in NWA 12217. This process is likely responsible for forming the symplectites in the related ultramafic achondrites NWA 12217, 12319, 12562, and 13954, along with many other achondrites. The nucleosynthetic Cr isotopic composition of chromites appears to be in disequilibrium with that of silicates in NWA 12217, suggesting that the liquids responsible for the symplectite forming reaction are at least partially sourced from a different parent body and result from an impact .