¹Ziqing Li, ²Mengfan Zhang, ¹Bo Zhang, ³Yuqi Qian, ⁴Tao Long, ⁴Xiaochao Che, ¹Ao Su, ⁵James W. Head
Journal of Geophysical Research: Planets, 131, e2026JE009898 Open Source Link to Article [DOI: 10.1029/2026JE009898]
¹Key Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Sciences, Peking University, Beijing, China
²School of Earth and Space Sciences and Institute of Energy, Peking University, Beijing, China
³Department of Earth and Planetary Sciences, NWU-HKU Joint Center of Earth and Planetary Sciences, The University of Hong Kong, Hong Kong, China
⁴Beijing SHRIMP Center, Institute of Geology, Chinese Academy of Geological Sciences, Beijing, China
⁵Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, RI, USA
Published by arrangement with John Wiley & Sons

The cause of the observed mare basalt asymmetry between the lunar nearside and farside remains a long-lasting conundrum. In this study, we characterized the petrology and geochemistry of the Chang’e-6 low-Ti basalts from the lunar farside, performed petrological modeling of major elements and conducted Monte Carlo simulation of trace elements, for Chang’e-6 and Chang’e-5 basalts. The results from multiple approaches indicate that the young Chang’e-6 (2.8 Ga) and Chang’e-5 (2.0 Ga) basalts both originated from shallow, depleted ilmenite-bearing cumulate (IBC). Based on remote sensing and thermodynamic constraints, we estimated the mantle source ilmenite abundance for young shallow-source basalts (<3.0 Ga) globally. The modeling results indicate that the mantle sources of these basalts on the nearside generally contains ∼16–32 wt% ilmenite, especially beneath the PKT, whereas the mantle sources of these basalts beneath the farside SPA basin only has ∼13–24 wt% ilmenite. The phase equilibrium calculations show that the nearside mantle sources with higher ilmenite abundance leads to a significant decrease in melting point and tends to produce more melt compared to farside mantle sources. Therefore, asymmetric IBCs may play a key role in accounting for asymmetric nearside/farside volcanism.

¹F. Alberquilla (>10)
Journal of Geophysical Research: Planets, 131, e2026JE009742 Open Source Link to Article [DOI: 10.1029/2026JE009742]
¹University of the Basque Country (EHU), Leioa, Spain
Published by arrangement with John Wiley & Sons

Volcanic tubes provide stable environments where unique mineralogical assemblages can form and be preserved, making them valuable terrestrial analogs for Martian studies. This work investigates tree-like structures within two lava tubes on La Palma Island (Canary Islands, Spain) through a comprehensive geochemical and mineralogical characterization. Samples were analyzed using X-ray diffraction (XRD), micro Energy Dispersive X-Ray fluorescence (µ-EDXRF), Raman microscopy, Scanning Electron Microscopy Energy-Dispersive X-ray Spectroscopy (SEM-EDX), Short-Wave infrared (SWIR) hyperspectral imaging, and multivariate analysis Principal Component Analysis and Multivariate Curve Resolution-Alternating Least Squares (PCA and MCR-ALS) to identify primary mineral phases and assess potential organic matter preservation. The results reveal that these structures are predominantly composed of hydrated silica (opal-A), with secondary phyllosilicates, carbonates, sulfates, and iron oxides. Organic signatures were identified as spectral features consistent with microbial pigments such as β-carotene within the opal matrix, suggesting the potential encapsulation and preservation during silica precipitation. Hyperspectral analyses revealed spectral features consistent with the presence of opal-A, calcite, and nontronite, highlighting complex mineral associations. The comparison with CRISM observations from Jezero Crater revealed similarities in mineral assemblages and suggests that comparable alteration pathways may have affected basaltic substrates, with hydrated silica formation followed by carbonate precipitation under evolving fluid conditions. These findings underscore the relevance of terrestrial lava tubes as analogs for Martian volcanic environments and emphasize the potential of hydrated silica deposits to preserve biosignatures in extraterrestrial contexts.

¹Alessandro Pisello (>10)
Journal of Geophysical Research: Planets 131, e2025JE009371 Open Source Link to Article [DOI: 10.1029/2025JE009371]
¹Department of Physics and Geology, University of Perugia, Perugia, Italy
Published by arrangement with John Wiley & Sons

Understanding how the glass/crystal ratio influences the spectral response of volcanic rocks is crucial for interpreting planetary remote sensing data. Here, four mafic rocks simulating a possible Martian composition were synthesized with identical bulk chemistry but different mineralogical assemblages, from fully amorphous to ∼70 wt.% crystal content, to investigate how crystal content affects Visible and Near-Infrared (VNIR) reflectance spectra. Bi-directional VNIR reflectance was collected at room temperature across a range of incidence (0°, 30°, 60°) and emergence (−70° to +70°) angles. The diagnostic absorptions of the two most abundant phases, pyroxene and glass, are not distinguishable in the spectra and can even reproduce the spectral fingerprint of olivine, absent from the samples; only minor iron oxides (magnetite and hematite, ∼1–7 wt.%) produce clearly identifiable absorptions. Instead, spectral slope emerges as the primary proxy for the glass/crystal ratio: NIR/VNIR slope decreases systematically with increasing crystal content, driven jointly by the incorporation of iron oxides and the loss of the positive-slope contribution of residual glass. Principal Component Analysis and k-means clustering independently confirm this control, identifying three clusters that map onto the glass/crystal ratio. This decoupling indicates that the crystal content of a mafic terrain cannot be inferred from pyroxene- or glass-related absorptions alone, but rather from spectral slope and iron-oxide features. These results experimentally support previous hypotheses linking the spectral diversity of Martian mafic terrains to their degree of crystal content and oxidation state and highlight variable glass abundance as an under-considered contributor to the spectral interpretation of the Martian surface.

^1,2,3Scott M. Perl, ^2,4Aaron J. Celestian, ⁴Frank A. Corsetti
Journal of Geophysical Research: Planets 131, e2026JE009730 Link to Article [DOI: 10.1029/2026JE009730]
¹Earth, Planetary, and Space Sciences, University of California Los Angeles, Los Angeles, CA, USA
²Mineral Sciences, Los Angeles Natural History Museum, Los Angeles, CA, USA
³Blue Marble Space Institute of Science, Seattle, WA, USA
⁴Department of Earth Sciences, University of Southern California, Los Angeles, CA, USA
Published by arrangement with John Wiley & Sons

Evaporite minerals can capture and entomb organic matter within their intercrystalline and intracrystalline structure because they precipitate relatively quickly (nomenclature adopted from Schopf et al. (2012), https://doi.org/10.1089/ast.2012.0827). Thus, evaporite minerals constitute a target for biosignature investigation on Earth and Mars, where evaporitic deposits are known to exist. However, little is known about the process of organic preservation and detection in evaporites, or the stability of such molecules when exposed to significant UV radiation as would be present on the surface of Mars. Here, we investigate the incorporation of β-carotene into halite (NaCl) by growing halite in the lab in the presence of know concentrations of β-carotene and examining the resultant precipitated crystals and fluid inclusions via Raman spectroscopy. Following brine evaporation, the experimental β-carotene-containing halite was exposed to UV-C to simulate conditions on the Martian surface. Results reveal that β-carotene has a strong Raman signature that remains intact even when entombed in halite. In particular, fluid inclusions within the halite displayed particularly strong β-carotene Raman signatures after UV-C exposure. Little change was observed even after several days of UV-C delivery. Our results reveal that complex organic molecules like β-carotene should be preserved well in halite (especially in fluid inclusions) and that halite does provide protection from organic matter degradation from UV-C radiation. Thus, evaporites constitute a good target for the search for biomarkers on Mars. These findings will allow for proper criteria for the discovery of any potential physical biosignature and chemical biomarker that would be on active ocean worlds (Europa, Enceladus) and for future Mars subsurface drilling missions.

¹S. Desikamani, ²L.D. Peterson, ¹M.E. Newcombe, ³C.M.O’D. Alexander, ³J. Wang, ¹R.D. Ash, ⁴S.G. Nielsen, ¹P.M. Piccoli, ³E.S. Bullock
Geochimica et Cosmochimica Acta, (in Press) Link to Article [DOI: 10.1016/j.gca.2026.08.024]
¹University of Maryland, College Park, MD 20742, USA
²Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
³Carnegie Institution for Science, Washington DC 20015, USA
⁴Centre de Recherches Pétrographiques et Géochimiques (CRPG – CNRS), Nancy 54501, France
Copyright Elsevier

Nucleosynthetic isotope signatures indicate that the Earth is predominantly made from inner solar system non-carbonaceous (NC) materials. However, a major uncertainty in models of water addition to the proto-Earth is the extent to which H (calculated in this study as µg/g H₂O, but present as H-bearing species) in nominally anhydrous minerals (NAMs) from NC materials could contribute to the bulk Earth water budget. The preserved water concentration of NC meteorite NAMs may also shape our understanding of processes occurring in the solar protoplanetary disk (e.g., implantation of H on the surfaces of NAM grains) and in planetesimals (e.g., metamorphism in chondrite parent bodies). Reported water contents for NAMs from the ordinary chondrites (OCs), the dominant NC material falling to Earth today, range between 10⁰-10⁴ µg/g H₂O. In order to better constrain the potential contribution of ordinary chondrites to the Earth’s water budget we have measured water concentrations in NAMs from eight equilibrated OCs, six of which have not previously been investigated for water, and two of which (Chelyabinsk and Bensour) were previously measured in other laboratories. We find that olivine and low-Ca pyroxene from equilibrated OCs contain less than ∼ 10 µg/g H₂O. Based on these measurements, the water content of the NAM fraction of equilibrated OCs is < 10 µg/g H₂O (a factor of ∼ 60–120 lower than prior estimates). Combining these constraints of equilibrated OC NAM water contents with published measurements of NAMs and glassy mesostases from unequilibrated OCs, we estimate that NAMs and glass in OC parent bodies could have delivered no more than ∼ 0.2 ocean masses of water to Earth (∼1% of an assumed total water budget of 18 ocean masses). Additional water could have been delivered from phyllosilicates and organics in the most primitive OC material that is not considered in our modeling. The difference in NAM water concentrations obtained here relative to some prior studies may be rooted in analytical artifacts associated with their nanoscale secondary ion mass spectrometric measurements.

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.