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.

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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 .

¹Pascal M. Kruttasch,^1,2Aryavart Anand,³Paul H. Warren,⁴Chi Ma,¹Klaus Mezger
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2024.08.012]
¹Institut für Geologie, Universität Bern, Baltzerstrasse 1+3, 3012 Bern, Switzerland
²Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
³Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095, USA
⁴Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
Copyright Elsevier

Establishing the temporal evolution of the ureilite parent body(ies) is crucial for understanding the quantitative timescale of planetesimal formation and evolution in the protoplanetary disk. In order to establish a timeline for these early processes, age constraints on the accretion, differentiation and secondary reduction were obtained with the short-lived ⁵³Mn-⁵³Cr chronometer to whole-rock and sequentially digested fractions of main group ureilites. A whole-rock isochron dates the reservoir-scale Mn-Cr fractionation in the ureilite parent body(ies), associated with magmatic differentiation, to 2.89-0.51+0.56 Ma after CAI formation. This age implies that the ureilite parent body(ies) accreted no later than ∼1.5 Ma after CAI formation, at a time when the NC-CC dichotomy was already established. The ⁵³Mn-⁵³Cr systematics of fractions from chromite-bearing ureilites yield an age of 4.29-0.45+0.49 Ma after CAI formation for a secondary reduction event on the parent body. This event is commonly associated with the catastrophic disruption of the ureilite parent body while still hot. The chromite model ages are consistent with the isochron ages obtained from chromite-bearing ureilites. Collectively these ages indicate that chemical differentiation processes were underway on the ureilite parent body(ies) during the time interval when undifferentiated meteorite parent bodies were forming, and may have paused at the peak of planetesimal formation when planetary collisions were common.

^1,2Shurui Chen et al. (>10)
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2024.116256]
¹College of Surveying & Geo-Informatics, Tongji University, Shanghai 200092, China
²The Shanghai Key Laboratory of Space Mapping and Remote Sensing for Planetary Exploration, Tongji University, Shanghai 200092, China
Copyright Elsevier

Exploring the concealed subsurface structures and materials beneath the lunar surface can reveal significant insights into geological history. This study offers a comprehensive analysis of the stratigraphic interpretation and subsurface material composition at the Chang’E-4 landing site, integrating both in-situ and orbital radar with multispectral datasets. We report the identification of a subsurface structure, which resembles a buried impact crater (~420 m in diameter) under the Yutu-2 rover’s path. This crater could degrade over a period of 0.42 to 0.53 Ga, with an initial diameter of 293 to 323 m and an initial depth of 45.9 to 51.4 m. Surface material above the buried crater, evaluated by the in-situ visible and near-infrared imaging spectrometer (VNIS) detector, shows a higher abundance of clinopyroxene compared to surrounding areas, where a near-equal mix of clinopyroxene and orthopyroxene is observed. Assessment of crater diameters in proximity to the Chang’E-4 landing site, along with the mineral compositions at their epicenters, reveals a decrease in the abundance of clinopyroxene and plagioclase with depth. Conversely, the quantities of orthopyroxene and olivine increase, implying that clinopyroxene-rich Finsen ejecta significantly influenced the Chang’E-4 landing site’s geological composition. Two potential stratigraphic boundary depths are identified at 13.5 and 22 m, based on pronounced variations in mineral abundance, offering fresh insights into subsurface delineation beyond radar data. Considering the VNIS and vertical mineral composition, we propose the buried crater’s formation resulted from Finsen crater’s ejecta. Also, we identify eight potential historical impacts by comparing subsurface relief variations with mineral composition ratios between clinopyroxene and orthopyroxene. The integration of subsurface structure, along with surface and subsurface mineral composition, enables a more robust stratigraphic interpretation, facilitates shallow material source analysis, and allows for historical impact tracing.

¹Philipp Zanon,¹Michelle Dunn, ¹Geoffrey Brooks
Icarus (in Press) Open Access Link to Article [https://doi.org/10.1016/j.icarus.2024.116257]
¹Swinburne University of Technology, John St, Hawthorn, Melbourne, 3122, Victoria, Australia
Copyright Elsevier

The detrimental effects and challenges of Lunar dust for Lunar exploitation were first identified during the Apollo missions. During the extra vehicle activities (EVAs) undertaken by astronauts, the dust clogged mechanisms, disrupted sensors, and caused several health issues for the astronauts. Despite numerous studies, there is no definite understanding as to why different Apollo missions experienced varying levels of dust disruptions. The variations in dust behavior could be attributed to the amount of radiation the Lunar soil is exposed to, as well as mineralogy and particle sizes. To enhance our understanding of Lunar dust behavior this study investigated Space Recourse Technologies, formally known as Exolith, simulant at different mineral compositions, and their surface detachment characteristics were measured. Experiments measuring the individual minerals and their mixed simulant-like counterparts were conducted using electrostatic fields. Inclusive to this, non-dried and dried samples were compared by measuring adhesion to target plates when subject to electrostatic forces. The results found that Highlands simulant exhibited a higher buildup on a target plate than its Mare counterpart by an average of 33% under the same conditions, likely due to particle size differences. In addition to these findings, evidence of particle reactivity decay was observed under repeated tests with up to 60% less Mare simulant and 36% Highlands deposition being measured compared to the first set of experiments. A possible explanation may be particle reactivity. Microscope images identified that particles are transported in groups as opposed to individual grains. These results will help researchers in tailoring dust mitigation solutions based on different regions on the Lunar surface and influence mission planning from the perspective of dust mitigation and contamination.