¹Richard J. Anslow,²Maylis Landeau,¹Amy Bonsor,^1,3Jonathan Itcovitz,^1,4Oliver Shorttle
Journal of Geophysical Research: Planets (in Press) Open Access Link to Article [https://doi.org/10.1029/2025JE009328]
¹Institute of Astronomy, University of Cambridge, Cambridge, UK
²Université de Paris, Institut de Physique du Globe deParis, CNRS, Paris, France
³Department of Civil and Environmental Engineering, Imperial College London, London, UK
⁴Department of Earth Sciences, University of Cambridge, Cambridge, UK
Published by arrangement with John Wiley & Sons

The excess abundance of highly siderophile elements (HSEs), as inferred for the terrestrial planets and the Moon, is thought to record a “late veneer” of impacts after the giant impact phase of planet formation. Estimates for total mass accretion during this period typically assume all HSEs delivered remain entrained in the mantle. Here, we present an analytical discussion of the fate of liquid metal diapirs in both a magma pond and a solid mantle, and show that metals from impactors larger than approximately 1 km will sink to Earth’s core, leaving no HSE signature in the mantle. However, by considering a collisional size distribution, we show that to deliver sufficient mass in small impactors to account for Earth’s HSEs, there will be an implausibly large mass delivered by larger bodies, the metallic fraction of which lost to Earth’s core. There is therefore a contradiction between observed concentrations of HSEs, the geodynamics of metal entrainment, and estimates of total mass accretion during the late veneer. To resolve this paradox, and avoid such a mass accretion catastrophe, our results suggest that large impactors must contribute to observed HSE signatures. For these HSEs to be entrained in the mantle, either some mechanism(s) must efficiently disrupt impactor core material into
0.01 mm fragments, or alternatively Earth accreted a significant mass fraction of oxidized (carbonaceous chondrite-like) material during the late veneer. Estimates of total mass accretion accordingly remain unconstrained, given uncertainty in both the efficiency of impactor core fragmentation, and the chemical composition of the late veneer.

¹Oleg S. Vereshchagin,¹Maya O. Khmelnitskaya,¹Natalia S. Vlasenko,¹Elena N. Perova,¹Mikhail N. Murashko,²Yevgeny Vapnik,¹Elena S. Sukharzhevskaya,³Albina G. Kopylova,^1,4Sergey N. Britvin
Journal of Geophysical Research: Planets (in Press) Link to Article [https://doi.org/10.1029/2025JE009396]
¹Saint Petersburg State University, University Embankment 7/9, St. Petersburg, Russian Federation
²Department ofGeological and Environmental Sciences, Ben‐Gurion University of the Negev, Beer‐Sheva, Israel
³Diamond and PreciousMetal Geology Institute, Siberian Branch, Russian Academy of Sciences, Yakutsk, Russia
⁴Nanomaterial Research Center,Kola Science Centre, Russian Academy of Sciences, Apatity, Russia
Published by arrangement with John Wiley & Sons

Iron is one of the most common elements on Earth and is present in the modern crust mainly in the form of (hydro)oxides and silicates, whereas terrestrial (telluric) native Fe is extremely rare. It is generally assumed that telluric Fe differs greatly in its chemical composition and mineralogy from the metal of iron meteorites, indicating different modes of formation. We uncover haxonite (NiFe22C6) and uakitite (VN) within telluric iron assemblages in terrestrial crustal rocks (volcanic rocks of the Norilsk ore region, Russia and metamorphic rocks of the Hatrurim Basin, Israel, respectively). Both minerals were previously discovered in iron meteorites and were thought to be absent in Earth’s crustal rocks. Consequently, we analyzed available data on terrestrial rocks containing native iron and iron meteorites and compared their oxygen-free mineral assemblages. The resemblance in mineralogy suggests that at least some metal-rich asteroids may have formed in a manner similar to telluric iron. We suggest that heating at low pressures (T ≈ 1000°C, P < 10 MPa) of the primary Fe-bearing silicates in the presence of organic matter led to the formation of an iron melt at low oxygen fugacity (up to 5 units below Fe-FeO buffer). Significant differences in the geochemistry of terrestrial and extraterrestrial iron are associated with different degrees of evolution of the primary minerals involved in their formation.

^1,2Xiaolong Guo,^1,2Peixin Du,³Hongmei Liu,⁴Jiacheng Liu,⁵Shangying Li,^1,2Xinyi Xiang,⁶Shun Wang,⁷Peng Yuan
Journal of Geophysical Research: Planets (in Press) Link to Article [https://doi.org/10.1029/2025JE009644]
¹State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Macau, China
²CNSA Macau Center for Space Exploration and Science, Macau, China
³Guangdong Provincial Key Laboratory ofMineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China
⁴Department of Earth Sciences and Laboratory for Space Research, The University of Hong Kong, Hong Kong, China
⁵School of Land Engineering, Chang’an University, Xi’an, China
⁶Qinghai Provincial Key Laboratory of Geology andEnvironment of Salt Lakes, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, China
⁷School ofEnvironmental Science and Engineering, Guangdong University of Technology, Guangzhou, China
Published by arrangement with John Wiley & Sons

Poorly ordered Al/Si phases are widely distributed across the surface of Mars, among which allophane and amorphous silica are the two main constituents. Both allophane and amorphous silica can form in Al-Si systems through surface chemical weathering or subsurface hydrothermal alteration of volcanic materials. Nevertheless, our comprehension of the products derived from Al-Si hydrolysis systems remains poorly constrained. Hydrolysis experiments were conducted on Al-Si systems across an unprecedentedly wide range of Si/(Al + Si) molar ratios (n, 0 ≤ n ≤ 0.9), followed by characterizing the products using multiple techniques. At n ≤ 0.1, the products consist predominantly of Al30 (an Al polycation with a Keggin structure) and poorly ordered Al hydroxides. The introduction of Si resulted in formation of a small amount of proto-allophane. At n = 0.2 and 0.3, poorly ordered materials were still dominant, along with the presence of well-crystallized bayerite and gibbsite. The proto-allophane increased in quantity and began to assemble into allophane. At n = 0.5, well-crystallized minerals were absent and allophane dominated the product. At n = 0.7, the amount of allophane decreased significantly and at n = 0.8 and 0.9, allophane was probably absent, although proto-allophane still formed. Meanwhile, an increasing amount of amorphous silica was formed. X-ray diffraction, Fourier transform infrared, and VNIR provide information for differentiating Al-rich phases and Si-rich phases but show limited capability in identifying poorly ordered Al/Si-rich phases. NMR is powerful for identifying poorly ordered Al/Si phases, although widespread iron on the martian surface and the large instrument pose challenges to its application on Mars.

^1,2,3Fengke Cao et al. (>10)
Journal of Geophysical Research: Planets (in Press) Link to Article [https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JE009228]
¹Research Center for Planetary Science, College of Earth and Planetary Sciences, Chengdu University of Technology,Chengdu, China
²Department of Earth Sciences, Western University, London, ON, Canada
³Institute for Earth & SpaceExploration, Western University, London, ON, Canada
Published by arrangement with John Wiley & Sons

Northwest Africa (NWA) 7034 and its paired meteorites represent polymict regolith breccias derived from the ancient Martian crust. We employed micro-X-ray diffraction and Raman spectroscopy to quantitatively assess impact-induced metamorphism in plagioclase and alkali feldspar. Strain-related mosaicity (SRM) was measured via full width at half maximum in the Debye ring or chi (χ) dimension (FWHMχ) from 2D XRD images. A total of 149 plagioclase and 21 alkali feldspar grains were analyzed. Plagioclase exhibits FWHMχ values from 0.5° to 10.9°, and alkali feldspar shows a range of 2.1°–9.7°. Plagioclase grains record peak shock pressures from 0 GPa (unshocked) to 28–30 GPa based on calibrations for experimentally shocked andesine. Approximately 26% of grains show no detectable shock deformation (<1.0 GPa), while ∼4% preserve evidence of severe shock (>21.0 GPa), indicative of exposure to at least moderate shock metamorphism prior to ejection from Mars. Alkali feldspar records higher apparent peak pressures, possibly spanning 4.7–28.5 GPa. Martian crustal minerals experienced highly heterogeneous shock effects, which highlights the complex and varied impact histories of feldspar minerals during the impact-induced brecciation process. Pressure differences between plagioclase and alkali feldspar may reflect distinct source regions, pre-lithification shock events, or differing shock responses. This study highlights the importance of multi-mineral analytical approaches to enhance the accuracy of shock pressure quantification in Martian regolith breccias and to reconstruct the planet’s impact processes. This methodology should also be applied to other extraterrestrial samples to characterize shock effects across planetary bodies in the solar system.

¹Pengyu Ren,¹Changqing Liu,¹Yuzhen Wang,¹Enming Ju,¹Xin Wang,¹Ruize Zhang,¹Yanqing Xin,¹Ying-Bo Lu,¹Zongcheng Ling
Journal of Geophysical Research: Planets (in Press) Link to Article [https://doi.org/10.1029/2025JE009532]
¹Shandong Key Laboratory of Space Environment and Exploration Technology, School of Space Science and Technology,Institute of Space Sciences, Shandong University, Weihai, China
Published by arrangement with John Wiley & Sons

The Mars Mineralogical Spectrometer (MMS) onboard the Tianwen-1 orbiter can obtain high-resolution visible and infrared reflectance spectra of the Martian surface, that supports detailed analysis of mineral types and their spatial distribution across Mars. However, raw MMS data cannot be directly applied to scientific analysis. To address this limitation, this paper develops a processing pipeline for MMS data, including radiance to I/F conversion, photometric correction, inhomogeneity correction, and geometric correction. Three global maps of ferric oxides were obtained using the processed MMS data. Results reveal that the ferric oxides are nearly ubiquitous across the Martian surface, and they primarily exist in the form of nanophase ferric oxides in the bright regions of Mars (e.g., Amazonis Planitia, Tharsis Montes, and Arabia Terra). Subsequently, the distribution of gray crystalline hematite is identified in Meridiani Planum and Aram Chaos using data from MMS. Additionally, a new deposit of red crystalline hematite is detected in the southeastern part of Aram Chaos. These findings provide crucial evidence for the existence of past aqueous environments in these regions, including Fe-rich aqueous fluids under ambient conditions, hydrothermal fluids, and in-place oxidative weathering of Fe-bearing rocks under the influence of surface water. Notably, the processing pipeline and methods established in this study are critical for advancing our understanding of the ferric oxide distribution across the Martian surface using MMS data.

^1,2Robert Platt,^1,2Rossella Arcucci,^1,3Cédric M. John
Journal of Geophysical Research: Planets (in Press) Open Access Link to Article [https://doi.org/10.1029/2025JE009473]
¹Department of Earth Science and Engineering, Imperial College London, London, UK,
²Data Science Institute, ImperialCollege London, London, UK,
³Digital Environment Research Institute (DERI), Queen Mary University of London,London, UK
Published ny arrangement with John Wiley & Sons

Orbital remote sensing observations are a lynchpin of planetary science research. Hyperspectral infrared spectroscopy in particular is key for planetary mineralogical exploration, for example, CRISM for Mars, as this underpins our understanding of the distribution of specific lithologies and the geological process leading to their formation. Yet routine analysis workflows involving summary parameters have significant limitations and are highly time-consuming. This work presents a novel methodology and framework for the analysis and classification of CRISM SWIR reflectance spectroscopy, leveraging Machine Learning (ML). We train a model to classify 37 minerals previously manually identified on the planet. We show this model is highly performant, with test data across Mars and a case study within Jezero crater, where ML results match previous manual analyses and rover observations. We also adapt Expected Cost (EC) to remote sensing data for use in geological context for the first time. We demonstrate that EC can be used to dynamically weight misclassification penalties based on geological context, as a rigorous measure of automated classification methods. We envision this model to make analysis of CRISM data more accessible to the planetary science community, allowing rapid searches for a vast range of minerals across a global/regional scale. As a result, areas of interest for further satellite or rover exploration can be quickly identified, leading to greater understanding of geological processes on Mars.

¹J. M. Meusburger,¹T. F. Bristow,¹D. T. Vaniman,¹E. B. Rampe,¹S. J. Chipera,¹D. F. Blake,¹S. L. Simpson,¹R. Y. Sheppard,¹G. Berlanga
Journal of Geophysical Research: Planets (in Press) Open Access Link to Article [https://doi.org/10.1029/2025JE009631]
¹Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
Published by arrangement with John Wiley & Sons

X-ray amorphous sulfate hydrates are a substantial component (up to 23 wt%) of the sedimentary rocks and sands analyzed to date by the Mars Science Laboratory Curiosity rover at Gale crater. Recently, the CheMin X-ray diffractometer observed the amorphization of the crystalline sulfate starkeyite (MgSO4 · 4H2O) upon exposure to the dry and relatively warm atmosphere inside the rover body. To assess the extent to which interactions between minerals and the rover environment contribute to the amorphous component, we investigated the stability of several hydrated minerals under Curiosity-like conditions. Our results show that highly hydrated minerals are more prone to transformation inside the rover than lower hydrates. Minerals that readily become amorphous under rover conditions are also likely to be unstable when exposed to the dry Martian atmosphere during the warm periods at noon. We therefore suggest that much of the observed amorphization occurred at the Martian surface prior to sampling. Future missions such as the Rosalind Franklin rover and Mars Life Explorer propose to drill into the substantially colder subsurface at Martian mid-latitudes and are likely to encounter temperature and humidity-sensitive cryohydrates. To evaluate the original mineral assemblage of rocks on such missions, it will be critical to maintain controlled temperature and relative humidity (RH) conditions inside the rover body. We find that increasing ambient humidity may induce the recrystallization of amorphous salt hydrates, thus controlling RH and temperature inside the rover would significantly enhance the analytical capabilities of a next generation X-ray diffractometer on Mars.

^1,2Aditya Das,¹Dwijesh Ray,³B. Astha,⁴Avirup Bose
Journal of Geophysical Research: Planets (in Press) Link to Article [https://doi.org/10.1029/2025JE009278]
¹Physical Research Laboratory, Ahmedabad, India
²Indian Institute of Technology Gandhinagar, Gandhinagar, India
³Indian Institute of Technology, Mumbai, India
⁴Indian Institute of Technology (Indian School of Mines), Dhanbad, India
Published by arrangement with John Wiley & Sons

The olivine of the Deccan Traps basalts undergoes aqueous alteration to iddingsite along fractures, irrespective of their forsterite (Fo) content. Low Fo olivine typically displays wide and relatively straight fractures, while picritic (high Fo) olivine shows serrated (saw-tooth) fractures, indicative of an in situ dissolution process. Low Fo olivine attributes a relatively higher degree of aqueous alteration as compared to high Fo under low-temperature conditions. The clay minerals associated with low Fo experienced mildly reducing conditions, reflecting multiple aqueous alteration events. High Fo in picritic basalts is characterized by a lower pH and water-to-rock ratio than low Fo in tholeiitic basalts. The higher concentration of Si in the clay mineral saponite suggests an acidic hydrothermal alteration process. Geochemical modeling suggests a closed system operating at low temperatures. Although the total duration of alteration was brief in both scenarios, low Fo underwent alteration over a longer period, resulting in a similar quantity of altered products. These findings may provide insights into the alteration processes of Mars by defining geochemical conditions and hydrodynamic properties. This may also reveal whether Martian meteorites (Nakhlites) mineral cracks changed in a single event or multiple occurrences. While terrestrial analogs differ in essential mineral composition (such as Fe and Mg levels), the alteration products and conditions closely resemble those of Martian meteorites, helping to understand Mars’ water-crust interaction. Additionally, phyllosilicates/clay minerals may induce the preservation of biosignatures on Mars, which remains a top priority of ongoing missions.

¹R. Christoffersen,²M. J. Loeffler,^1,3S. Kanee,⁴C. J. Cline II,⁴L. P. Keller,¹T. M. Erickson,^5,6J. Fontanese,⁷T. Munsat,^5,6M. Horányi
Journal of Geophysical Research: Planets Open Access Link to Article [https://doi.org/10.1029/2025JE009257]
¹Amentum, NASA Johnson Space Center, Houston, TX, USA,
²Department of Astronomy and Planetary Science, NorthernArizona University, Flagstaff, AZ, USA,
³Now at Department of Earth & Environment, Boston University, Boston, MA,USA,
⁴NASA Johnson Space Center, Houston, TX, USA,
⁵Laboratory for Atmospheric and Space Physics, University ofColorado, Boulder, CO, USA,
⁶NASA SSERVI’s Institute for Modeling Plasma, Atmospheres and Cosmic Dust(IMPACT), University of Colorado, Boulder, CO, USA,
⁷Department of Physics, University of Colorado, Boulder,CO, USA
Published by arrangement with John Wiley & Sons

The flux of solar system meteoroids is dominated by objects less than 1 mm in diameter whose impact effects play a major role in the space weathering of airless body surfaces. These effects remain poorly characterized with respect to their dependence on the range of impact speeds for meteoroids across the inner solar system. We investigated this dependence specifically for the mineral olivine using an electrostatic dust accelerator to bombard olivine single crystals with a stream of Fe metal dust particles traveling at measured speeds between 0.3 and 20 km s⁻¹. The impacting particles produced microcraters 0.2–5.2 μm in diameter whose content of impact melt, and brittle/ductile shock-induced deformation features, were characterized by scanning and transmission electron microscopy. While particles traveling <1 km s⁻¹ were not able to form microcraters, analysis of the size versus speed relations for the faster particles allowed their impact speeds and maximum shock pressures to be statistically constrained. Microcraters 0.2–0.5 μm in diameter contain olivine-composition shock melt estimated to have formed at impact speeds as high as 15–20 km s⁻¹, and shock pressures more than 250 GPa. Transmission electron microscope studies of shock melt in larger, ∼1.5 μm diameter, microcraters found it was free of impact-generated nanophase metallic Fe (npFe⁰). The impact speeds for these craters of 3.0–5.0 km s⁻¹ suggest that in asteroid regoliths dominated by olivine, still higher impact speeds may be necessary to allow npFe⁰ to be produced.

¹F. Alberquilla et al. (>10)
Journal of Geophysical Research: Planets 131, e2025JE009515 Open Access Link to Article [https://doi.org/10.1029/2025JE009515]
¹IBeA Research Group (Ikerkuntza eta Berrikuntza Analitikoa ‐ Analytical Research and Innovation), Department ofAnalytical Chemistry, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Leioa, Spain
Published by arrangement with John Wiley & Sons

The study of terrestrial lava tubes is essential for understanding geological processes occurring during volcanic activity on other planetary bodies, such as Mars. These processes lead to the formation of minerals analogous to those found on other planets. Volcanic eruptions are often associated with hydrothermal activity and gas emissions (e.g., CO2, SO2, H2S, HCl, H2O, H2) through fumaroles, which can simulate Martian atmospheric conditions. These gases and fluids interact with the host rock, leading to mineral alteration and the formation of secondary minerals. This study analyzes the Cueva del Vidrio lava tube on La Palma (Canary Islands, Spain), formed during the 1949 San Juan eruption. Although its materials exhibit low alteration due to their relatively recent origin, the 2021 Tajogaite eruption introduced new gas emissions, groundwater interactions, and surface runoff, thereby promoting the formation of alteration crusts and coatings. The methodology combined minimally invasive techniques, such as X-ray diffraction, and non-destructive techniques, including X-ray fluorescence (μEDXRF) and Raman spectroscopy. In order to facilitate the interpretation of the results, runoff waters were analyzed by ion chromatography. The results highlight the presence of carbonates, sulfates, and iron oxides, notably hematite, which likely formed from silicate weathering, particularly olivine alteration, leading to iron depletion and magnesium enrichment. Additionally, amorphous silica was identified, likely formed through reactions involving sulfate and carbonate precipitation, which leached silicon from silicate-rich host rocks. Similar processes have been described on Mars, where opal is considered a key mineral for astrobiological investigations due to its potential for preserving biosignatures.