¹Fabrizio Di Fiore, ²Michele Cassetta
Journal of Geophysical Research: Planets, 131, e2026JE009904 Open Source Link to Article [DOI: 10.1029/2026JE009904]
¹Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy
²Department of Engineering for Innovation Medicine, University of Verona, Verona, Italy
Published by arrangement with John Wiley & Sons

Silicate melt viscosity plays a pivotal role in the evolution of rocky bodies within the Solar System, exerting first-order control on mantle differentiation and stratification, while dictating the metal-silicate separation and the subsequent volcanic activity. Thus, predicting the viscosity of planetary compositions is essential to model and better understand their thermomechanical evolution. Notably, the chemical signatures of primordial planetary magmas, marked by extreme Fe, Mg, and Ca enrichment, drive a highly depolymerized and fragile rheological regimes that frequently fall beyond the calibration data sets used to model the viscosity. In this study, we characterize the effect on viscosity by doping a basalt with iron, magnesium, and calcium to resemble an exotic planetary composition. By integrating high- and low-temperature viscometry with Raman spectroscopy and ultrasonic data, we show that this chemical enrichment significantly impacts the rheology, elasticity and the structural organization of the doped melt. In particular, viscosity decreases ∼2 times at high temperatures compared to the original basalt. This behavior is driven by the extreme depolymerization of the melt, and it is reflected in a shift toward Q² and Q¹ structural units. Vibrational analysis via the Boson Peak confirms a highly fragile state characterized by noticeably small correlation lengths. We tested several widely used semi-empirical models and found that while traditional empirical formulations struggle to accurately predict the viscosity of these exotic compositions, spectroscopy-based frameworks provide significantly better accuracy. This performance highlights the fundamental link between atomic-scale vibrational properties and melt-scale dynamics.

¹S. R. Baker, ^1,2,3,4B. L. Ehlmann
Journal of Geophysical Research: Planets, 131, e2025JE009605 Open Source Link to Article [DOI: 10.1029/2025JE009605]
¹Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
²Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
³Department of Geological Sciences, University of Colorado, Boulder, CO, USA
⁴Department of Astrophysical & Planetary Sciences, University of Colorado, Boulder, CO, USA
Published by arrangement with John Wiley & Sons

Aluminum phyllosilicates occur in 1–10s of km² exposures of Noachian (∼3.7 Ga) rock across Mars and typically appear stratigraphically above Fe/Mg-phyllosilicates. These units have been proposed to represent pedogenic basalt weathering sequences. We examine Al-phyllosilicates in the Nili Fossae region, combining mineral maps generated from imaging spectroscopy with digital elevation models and high-resolution imagery to determine mineral assemblages, their geologic relationships, and their history of formation. We find that the Al-phyllosilicate is dominantly kaolinite and lacks associated Fe oxide. The Al-phyllosilicates typically have a distinct texture relative to Fe/Mg-phyllosilicate units, indicating an unconformity, and two different protoliths rather than formation as a pedogenic weathering sequence. Layers in some kaolinite deposits and their preferential association with sedimentary basins suggest reworked sedimentary material. The most plausible source is an Al/Si-enriched (non-basaltic) airfall volcanic deposit. We detect sparse jarosite closely associated with kaolinite but not Fe/Mg-phyllosilicate. We interpret that the jarosite, which is metastable under present surface conditions, formed from reaction between Fe-enriched fluids and S that is found sufficiently only within the kaolinite-bearing protolith. Collectively, these observations suggest less intense near-surface oxidative weathering than the basalt pedogenesis hypothesis, namely, an upper bound of several million cumulative years of aqueous activity in Nili Fossae that largely ended after the formation of jarosite. Detection of Al-phyllosilicate-bearing float rocks in nearby Jezero Crater by the Perseverance Rover shows that sample return has potential to conclusively determine processes and environmental conditions forming Nili Fossae’s distinctive Al-phyllosilicates.

¹Marco A. G. Andreoli (>10)
Journal of Geophysical Research: Planets, 131, e2026JE009901 Link to Article [DOI: 10.1029/2026JE009901]
¹School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
Published by arrangement with John Wiley & Sons

In this paper we report the discovery, in the Gilf Kebir Plateau of southwest Egypt, of the first natural occurrence of Diamond-Like-Carbon, of microdiamonds, and new ultra-high T (≥1300°C) silicates, phosphates in boulders and pebbles of a mullite and magnetite melt rock. We also report, in the regolith of the Libyan Desert Glass (LDG) strewn field, comparable mullite-magnetite pebbles and, in paleosols, Diamond-Like-Carbon, N-rich amorphous carbon, aliphatic hydrocarbons, moissanite, and metallic spherules and grains of native Ti. These findings point to a ∼350 km, south to north strewnfield of melt rocks and their related disaggregated debris formed by the impact of a carbonaceous meteorite in the Jebel Uweinat, near the Egypt-Sudan border. At the northern end of their fluvial depository, the reworked debris co-mingled with the LDG strewnfield, likely originated from a second impact in the Gilf Kebir. The date of the diamonds-forming mullite impact melt is undetermined but tentatively linked to the 29 Ma event of the LDG, because disordered carbon + aliphatic compounds were found in a glass and in the, extraterrestrial (extrasolar) “Hypatia” from the same areas. The latter is considered as relic of the original, parent impactor.

¹I. Spring, ²T. Erickson, ¹A. Mallik, ¹A. Roy, ³A. Treiman
Journal of Geophysical Research: Planets, 131, e2026JE009689 Link to Article [DOI: 10.1029/2026JE009689]
¹Department of Geosciences, University of Arizona, Tucson, AZ, USA
²NASA Johnson Space Center’s Astromaterials Curation and Research Laboratory, Houston, TX, USA
³Lunar and Planetary Institute (USRA), Houston, TX, USA
Published by arrangement with John Wiley & Sons

Lunar dunite clast, D1, from lunar meteorite NWA 11421 represents the first lunar sample thatpotentially traces back to the lunar mantle and may provide insights into the Moon’s interior structure andchemistry. We conducted electron backscatter diffraction (EBSD) analysis of the clast to characterize its olivinemicrostructures and preferred orientations and to quantify its shock history. The EBSD data indicate that D1olivine grains are generally elongate with a moderate shape preferred orientation and a weak B‐typecrystallographic preferred orientation. Intragrain misorientations indicate that D1 experienced a high‐pressure,low‐temperature shock event. Grain orientation spread (GOS) indicates a weighted shock stage of 4.1 ± 1.3,corresponding to shock pressures of 15–20 GPa. Crystallographic rotation axes associated with low‐angle(2–10°) misorientations demonstrate preferential activation of C‐type slip, consistent with the relatively lowshock temperatures of 720 ± 99°C that were estimated using previously published linear relationships ofexperimentally shocked olivine. Notably, this shock temperature is below the sample’s equilibrium temperatureof 980 ± 20°C, as determined by two‐pyroxene thermometry. This contrast suggests that the thermal stateachieved during shock was conducive to preserving the primary mantle chemistry. The olivine fabric within D1displays J‐ and M‐indices consistent with other shocked meteorites; notably, the M‐index of these meteorites islower than that of terrestrial mantle xenoliths. Combined with the sample’s depth of origin, these characteristicssuggest D1 was excavated from either the Imbrium or Serenitatis basins and may provide the first chemicalconstraints on nearside lunar mantle.

^1,2Shixin Zhang, ^1,3,4Yachen Xie, ^4,5Yifei Liu, ^1,3,4Dongzhan Wu, ^1,2Bowen Liu, ⁴Wei Liu, ⁴Hongtao Wang, ⁴Yanyan Li, ^4,5Cunbao Li, ^4,5Heping Xie
Journal of Geophysical Research: Planets, 131, e2026JE009932 Link to Article [DOI: 10.1029/2026JE009932]
¹State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering, Sichuan University, Chengdu, China
²College of Architecture and Environment, Sichuan University, Chengdu, China
³College of Water Resource and Hydropower, Sichuan University, Chengdu, China
⁴State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering, Shenzhen University, Shenzhen, China
⁵Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization, College of Civil and Transportation Engineering, Institute of Deep Earth Sciences and Green Energy, Shenzhen University, Shenzhen, China
Published by arrangement with John Wiley & Sons

Deep-space exploration requires reliable mechanical constraints for lunar materials; however, the scarcity of samples limits destructive macroscale testing. Here, we combine automated mineralogical analysis and nanoindentation to investigate the mineral-scale mechanical behavior of two Chang’e-5 regolith particles and a Laâyoune 002 feldspathic breccia comparison sample. Rather than treating these materials as bulk proxies for all mare and highland regolith regions, we compare analogous mineral domains using an identical testing protocol. Minerals in the Chang’e-5 particles generally show lower elastic modulus and hardness, greater indentation depth and creep displacement, and higher plastic work ratios than analogous minerals measured in the interior polished section of Laâyoune 002. The strongest contrast occurs in ilmenite, where more plastic, energy-dissipative deformation is observed. These measured contrasts document micromechanical differences among analogous minerals in the analyzed lunar samples. Their interpretation considers lithology, mineral chemistry, local microstructure, and impact history, with regolith processes and space-weathering overprint as plausible contributors to the Chang’e-5 response. First-order homogenization of the analyzed particle-scale assemblages yields equivalent elastic moduli of about 54 GPa for the Chang’e-5 assemblage and about 78 GPa for the Laâyoune 002 assemblage. These results provide mineral-resolved mechanical constraints for interpreting lunar material evolution and for designing better simulants, experiments, and multiscale engineering assessments.

¹Ziyan Han (>10)
Earth and Planetary Science Letters, 693, 120294 Link to Article [DOI: 10.1016/j.epsl.2026.120294]
¹State Key Laboratory of Critical Earth Material Cycling and Mineral Deposits & Lunar and Planetary Science Institute, School of Earth Sciences and Engineering, Nanjing University, Nanjing, Jiangsu, 210023, China
Copyright Elsevier

The Moon is currently airless, but intense impact bombardments in its history may have resulted in transient atmospheres on the early Moon. However, the existence and scale of the impact-induced atmosphere have remained speculative. Here, we identified pervasive Na and K in-gassing profiles in Chang’e 6 impact glass beads that were produced from formation of craters with diameters larger than 10 m. These profiles were generated in the impact plumes where both Na and K partial pressures were larger than 10^–6 to 10^–4 bar. Using mass balance calculations, the total vapor pressures in the impact plumes containing H, N, S, C, Cl, and F could have been larger than 10^–5 to 10^–3 bar. Combined with lunar impact-flux models, our results imply that impact bombardments could have provided an important mechanism capable of generating a global transient atmosphere on the Moon with high impact flux at ≥4.4 Ga, and younger impacts alone likely only sustained local transient atmospheres as impact flux decreased after 4.4 Ga.

^1,2Elias Wölfer, ^1,2Christoph Burkhardt, ²Gerrit Budde, ²Christian A. Jansen, ²Jonas Pape, ^1,2Thorsten Kleine
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Article [DOI: 10.1016/j.gca.2026.08.021]
¹Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
²Institut für Planetologie, University of Münster, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany
Copyright Elsevier

Nucleosynthetic isotope anomalies allow distinguishing between non-carbonaceous (NC) and carbonaceous (CC) type meteorites, and have revealed correlated isotope variations especially among NC bodies. Understanding the origin of this NC trend is important for identifying the processes that produced the NC isotope heterogeneity, and for using these isotope anomalies to reconstruct the early evolution of the solar protoplanetary disk. We report mass-independent Ti, Cr, and Mo isotope compositions for a comprehensive set of previously not or only poorly investigated meteorites, as well as acid leachates obtained from the sequential digestion of primitive ordinary chondrites. Some of the samples investigated in this study fill previously identified apparent gaps in the NC trend, suggesting these gaps reflect unrepresentative sampling of a more continuous isotopic trend. Bulk meteorites and leachates exhibit distinct isotope systematics, indicating that the NC isotope variability does not reflect selective thermal processing of presolar carriers in the disk. The NC trend also cannot reflect the continuous addition of CC dust from the outer to the inner disk, because early- and late-formed NC meteorites display largely overlapping isotopic compositions. Instead, we find that the NC isotope heterogeneity is best accounted for by fractionation and mixing among chemically and isotopically distinct dust components, similar to the processes that produced the isotopic variability among carbonaceous chondrites. On this basis we argue for the presence of substructures in the inner disk, which facilitated fractionation and mixing among distinct dust components, and helped preserve a long-lived dust reservoir from which NC planetesimals accreted over an extended period of time.

¹Scott J. VanBommel (>10)
Science, 393, 820-825 Link to Article [DOI: 10.1126/science.adu5501]
¹McDonnell Center for the Space Sciences, Department of Earth, Environmental, and Planetary Sciences, Washington University in St. Louis, St. Louis, MO, USA.
Reprinted with permission from AAAS

Martian rocks are known to contain sulfur-bearing species, including sulfates and sulfides. These compounds record a sulfur cycle that operated over the geological evolution of Mars. We used the Curiosity rover to investigate a deposit of light-toned stones in Gediz Vallis within Gale crater on Mars and found that the stones are composed of native sulfur. The sulfur deposit appears to have formed in place, within a sinuous entrenched canyon cut into the floor of Gediz Vallis. The presence of native sulfur implies that a sulfur enrichment pathway involving buoyant subsurface fluids operated on ancient Mars. We propose that the primary source of this sulfur was magmatic vapor, which cooled in the near subsurface cryosphere and was released by decompression during the erosion of Gediz Vallis.

¹Pengfei Zhang (>10)
Journal of Geophysical Research: Planets (in Press) Link to Article [DOI: 10.1029/2026JE009859]
¹Center for Lunar and Planetary Sciences, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
Published by arrangement with John Wiley & Sons

China plans to return samples from the near-Earth asteroid (469219) Kamoʻoalewa, which we previously identified as an LL-chondrite-compositional, highly space-weathered object with fine-grained regolith. In this study, we developed 10 mL of Kamoʻoalewa regolith simulant, designated “IGCAS-AST01,” by irradiating LL5/6 chondrite (Kheneg Ljouâd) powder with a high-energy pulsed laser. We then analyzed the composition, grain size distribution, density, porosity, visible to near-infrared reflectance spectrum, emission spectrum (approximated as 1–Reflectance), thermal diffusivity, specific heat capacity, and microstructural features of both the fresh (unirradiated) powder and IGCAS-AST01. IGCAS-AST01 is composed of 57.8 vol.% olivine, 19.9 vol.% orthopyroxene, 5.6 vol.% diopside, 12.2 vol.% plagioclase, 2.6 vol.% troilite, and minor amounts of other phases. It has a mean size of 26.99 μm, a median size of 23.19 μm, a density of 1196.8 kg m⁻³, and a porosity of 64.3%. Additionally, IGCAS-AST01 exhibits a low reflectance of 0.1 at 0.55 μm and an extremely steep spectral slope. In the temperature range of 253.15–473.15 K, its thermal diffusivity and specific heat capacity range from 3.6–4.7 × 10⁻⁶  m² s⁻¹ and 718.43–890.20 J kg⁻¹ K⁻¹, respectively. Furthermore, thick amorphous rims and abundant nanophase metallic iron particles are observed in olivine and pyroxene grains of IGCAS-AST01. These results could support the Tianwen-2 mission’s payload calibration, sampling operations, on-orbit scientific data interpretation, and future sample analysis.

^1,2M. Kołodziej, ³B. Pieterek, ⁴G. Zieliński, ¹K. Załęski, ¹E. Coy
Journal of Geophysical Research: Planets (in Press) Open Source Link to Article [DOI: 10.1029/2026JE009937]
¹NanoBioMedical Centre, Adam Mickiewicz University in Poznan, Poznan, Poland
²Institute of Molecular Physics, Polish Academy of Sciences, Poznan, Poland
³Geohazard Research Unit, Institute of Geology, Adam Mickiewicz University in Poznan, Poznan, Poland
⁴Micro-area Analysis Laboratory, Polish Geological Institute—National Research Institute, Warsaw, Poland
Published by arrangement with John Wiley & Sons

Meteorites serve as an exceptional source of insight into our planet and the Solar System. Most meteorite fragments were recovered hundreds to thousands of years after their fall, and therefore exhibit varying degrees of terrestrial weathering, which has altered or completely removed weather-sensitive mineral phases. This study focuses on two aubrites—NWA 14582 and Ribbeck—examining the differences in their mineral composition. The NWA 14582 was collected in a desert long after its fall and has undergone significantly greater shock metamorphic alteration than the Ribbeck meteorite. The alterations are evidenced by the structural changes in its enstatite and diopside, along with the absence of feldspars, which have transformed into maskelynite. The Ribbeck meteorite, recovered shortly after its descent, revealed several mineral phases not present in NWA 14582. Electron microprobe investigations confirmed that minerals such as troilite, daubréelite, schreibersite, and kamacite exhibit resistance to weathering. Conversely, the observed minerals, such as heideite, caswellsilverite, oldhamite, pentlandite, and alabandite, appear to be particularly susceptible to terrestrial weathering processes. Our observations further indicate that the climate at the fall site can have a substantial impact on the preservation of primary mineral phases and the formation of secondary weathering products. We additionally report a Cu-based iodide in an early sample preparation that was not preserved in subsequently prepared mounts, as well as a rare Al–Cu–Zn alloy in Ribbeck. Further microchemical and isotopic analyses are required to determine the provenance of these phases.