Fred Jourdan^a,b,c, Nicholas E. Timms^c, Tomoki Nakamura^d, William D.A. Rickard^b, Celia Mayers^b

Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2025.09.020]
^aWestern Australian Argon Isotope Facility, Curtin University, Australia
^bJohn de Laeter Centre, Curtin University, Australia
^cSpace Science and Technology Centre & School of Earth and Planetary Sciences, Curtin University, Australia
^dLaboratory for Early Solar System Evolution, Department of Earth Science Graduate School of Science, Tohoku University Aoba, Sendai, Miyagi Japan
Copyright Elsevier

Asteroid Itokawa is made of reassembled fragments from a monolithic parent asteroid which got shattered during a collision with a large object. Data are scarce regarding the metamorphic processes that occurred on the monolithic parent body and the age and nature of the catastrophic disruption event. Here, we investigate the timing of the metamorphism inside the parent body of Asteroid Itokawa and the age and nature of the catastrophic breakup event recorded in particles returned from Itokawa. We studied three regolith dust particles recovered by the Hayabusa space craft from the rubble pile asteroid 25,143 Itokawa using electron backscatter diffraction, time-of-flight secondary ion mass spectrometry, and ⁴⁰Ar/³⁹Ar dating techniques. Our results show that none of the particles show noticeable sign of shock metamorphism. Two of the particles yielded ⁴⁰Ar/³⁹Ar age of 4559 ± 61 and 4130 ± 33 million years (Ma), while a third particle returned a maximum error age of 703 ± 53 Ma. When combined with existing data, and diffusion models, these results show that ∼4.5 billion years (Ga) ago, Itokawa’s parent monolithic body cooled down from a peak metamorphism temperature ∼800 °C to ∼300 °C in less than 64 million years at a depth of >20 km. Then at ∼4.22 Ga, Itokawa’s parent body was shattered in a collisional process involving a heterogeneous temperature distribution during the impact, with some regions escaping shock metamorphism and experiencing less than a few hundred degrees Celsius. The fragments re-agglomerated in a larger rubble pile body where they subsequently cooled down over tens of millions of years. For the next 4 billion years, Asteroid Itokawa was regularly impacted and progressively shrunk by mass wasting.

Damanveer S. Grewal^a, Sujoy Mukhopadhay^b

Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2025.09.014]
^aDepartment of Earth and Planetary Sciences, Yale University, New Haven, CT 06511, USA
^bSchool of Earth and Space Exploration, Arizona State University, Tempe, AZ 85281, USA
Copyright Elsevier

The distinct accretionary histories of Earth and Mars – with Earth experiencing protracted growth and small contributions from outer solar system (carbonaceous, CC) materials, and Mars undergoing rapid growth with building materials drawn almost exclusively from the inner solar system (non-carbonaceous, NC) – highlight key differences in planetary formation. These contrasts underscore the importance of a comparative planetology framework for understanding the origin of volatiles in terrestrial planets. In this study, we examined the relationship between the carbon (C) isotopic compositions of planetary and planetesimal reservoirs to trace the origin of volatiles on Earth and Mars. The mean δ13C value of magmatic C in Martian meteorites (−20 ‰) is significantly lower than that of the bulk silicate Earth (BSE), with a canonical value of −5 ‰. While basaltic achondrites, magmatic iron meteorites, and ordinary chondrites from the NC reservoir display δ13C values similar to Martian meteorites, the BSE δ13C value is comparable to volatile-rich CC chondrites such as CI, CM, and CR, as well as with enstatite chondrites and ureilites from the NC reservoir. If Martian magmas underwent minimal C isotopic fractionation during degassing or degassed under kinetic conditions, then the δ13C value of the Martian mantle likely reflects accretion from thermally processed undifferentiated (ordinary chondrite-like) and differentiated NC materials. In contrast, if extensive degassing occurred via Rayleigh fractionation under equilibrium conditions, the δ13C value of the Martian mantle would have a higher δ13C value (−12 to −10 ‰) than that recorded in Martian meteorites – though still lighter than that of the canonical BSE δ13C. This implies a contribution from relatively 13C-rich NC materials, potentially similar to enstatite chondrites. For BSE, although the canonical δ13C value of –5 ‰ overlaps with those of enstatite chondrites and ureilites, the late-stage delivery of volatile-rich CC materials during the main phase of Earth’s growth, which was critical for establishing its water and nitrogen inventories, likely biased its C isotopic composition towards a CC-like signature. However, a lower mean δ13C value of −8.4 ‰ of the MORB mantle, as proposed by recent studies, could mean that Earth’s mantle still preserves the signature of 13C-poor, thermally processed NC materials accreted during the early stages of the planet’s growth. The observed heterogeneity in mantle C isotopic compositions, similar to that seen in H and N isotopes, could therefore reflect a mixed contribution from both NC and CC materials. These findings suggest that the δ13C value of the BSE could be lower than the canonical estimate and may align more closely with the proposed value for the MORB mantle. Taken together, these findings suggest that the contrasting accretionary histories of Earth and Mars led to fundamentally different pathways for volatile acquisition. These divergent pathways likely shaped the long-term geochemical evolution of each planet and influenced their potential for habitability.

Li Zhao^a,b,e, Liwu Li^a,c, Chunhui Cao^a,c, Qingyan Tang^d, Xianbin Wang^a

Icarus (in Press) Open Access Link to Article [https://doi.org/10.1016/j.icarus.2025.116803]
^aInstitut für Planetologie, Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany
^bDepartment of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912, USA
^aApollo 15 Commander, USA
Copyright Elsevier

Peng Chen^a et al. (>5)

Icarus (in Press) Open Access Link to Article [https://doi.org/10.1016/j.icarus.2025.116808]
^aHigh Pressure Science Experiment Center, College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
Copyright Elsevier

Courtney Jean Rundhaug^a, Martin Schiller^a, Martin Bizzarro^a, Zhengbin Deng^a,b, Hermann Dario Bermúdez^c,d,e
Earth and Planetary Science Letters 669, 119592 Open Access Link to Article [https://doi.org/10.1016/j.epsl.2025.119599]
^aCentre for Star and Planet Formation, Globe Institute, University of Copenhagen, Øster Voldgade 5–7, 1350 Copenhagen K, Denmark
^bDeep Space Exploration Laboratory/CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, China
^cDepartment of Earth and Environmental Studies, Montclair State University, Montclair, NJ 07043, USA
^dGrupo de Investigación Paleoexplorer, 1400-37 Trexlertown Rd, PA 18062, USA
^eDepartamento de Geociencias, Universidad Nacional de Colombia, Bogotá 11001, Colombia

The Cretaceous-Paleogene boundary (KPB) represents a massive extinction event in Earth’s history, probably triggered by the Chicxulub asteroid impact ∼66 Ma. The event dispersed vast volumes of ejecta materials including exceptionally preserved impact spherules in the Gorgonilla Island KPB section. Previous work identified three populations of spherules at Gorgonilla: 1) ballistically transported molten spherules, 2) a mixture of molten and condensed spherules dispersed by the expansion of a high-temperature, turbulent cloud (the “pyrocloud”), and 3) tiny droplets condensed from the plume (the “fireball layer”). We determine the Mg, Fe, and Ca isotopic compositions of pristine spherules to better understand the evaporation and condensation thermodynamics within the pyrocloud. We detect enrichment in mass bias corrected µ⁴⁸Ca and µ²⁶Mg* isotope signatures from the terrestrial value corresponding to an impactor contribution of ∼17–25%, most likely from a CM or CO chondrite-like asteroid. The mass-dependent δ²⁵Mg and δ⁵⁶Fe compositions are generally light or unfractionated, suggesting incomplete recondensation as the pyrocloud cooled and expanded. Combined δ²⁵Mg and δ⁵⁶Fe signatures reveal decoupling of these isotope systems, likely due to differing condensation rates. Thus, we calculate a higher average condensation rate of Fe than Mg, reflecting the thermodynamic decoupling and more complete recondensation signatures of Fe in the pyrocloud vapor. While we uncover information about the evaporation and condensation thermodynamics in the pyrocloud, the exact formation mechanisms of the complete suite of spherules remain complex with some spherules potentially forming from multiple mechanisms, including recondensation and splash–melting.

Linxi Li^a,b,d, et al. (>10)

Icarus (in Press) Open Access Link to Article [https://doi.org/10.1016/j.icarus.2025.116802]
^aState Key Laboratory of Lithospheric and Environmental Coevolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
Copyright Elsevier

Elizabeth F.M. Atang
Icarus (in Press) Open Access Link to Article [https://doi.org/10.1016/j.icarus.2025.116790]
University of Idaho, Department of Physics, 875 Perimeter Dr. MS 0903, Moscow, ID 83844-0903, USA
Copyright Elsevier

Marwane Mokhtari, Bernard Bourdon

Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2025.116801]
Laboratoire de Géologie de Lyon, Terre Planètes Environnement, ENS de Lyon, CNRS, Université Lyon 1. 46 Allée d’Italie, 69007 Lyon, France
Copyright Elsevier

Recent astronomical observations have shown that dust can get locally concentrated in protoplanetary disks, forming ring structures. The thermal processing of such regions could lead to dust evaporation and local enrichment of the solar gas in condensable elements. Previous studies focusing on major element behavior have shown that condensation of such dust-enriched gas could lead to the formation of a silicate melt with compositions resembling that of chondrules. However, previous studies focusing on dust-enriched environments were restricted to a limited set of elements. To study the mineralogical and chemical composition of condensates in these conditions, we have performed equilibrium calculations using the FactSage™ software for a dust-enriched solar gas. The calculations were done with dust-enrichment factors of 1 (solar composition), 10 and 100 at pressures ranging from 10−6 bar to 10−3 bar, for a CI-chondrite dust and a H-chondrite dust. The trace element condensation was accurately modelled with newly calculated activity coefficients in different solid and melt solutions. The available gas phase database was completed with new trace element species that are important to consider in oxidized conditions. The mineralogical sequence, melt composition and condensation temperature for all condensable elements were then quantified.
Our calculations show that the iron contents of olivine in equilibrium with a gas that is x100 enriched in CI-dust is consistent with that of amoeboid olivine aggregates and chondrules. Furthermore, our estimated temperature at which fayalite can form in these conditions is higher than what was previously proposed, enabling diffusion and homogenization of iron in olivine. The calculated composition of refractory metals for a x10 and x100 CI-dust enriched gas at 10−4 bar is consistent with the measured compositions of refractory metal nuggets. The possibility for these grains to have fractionated in an H2O ice-enriched gas can be ruled out as the calculated fractionation patterns in this case did not match the observed compositions.

¹A. Tavernier,^2,3G. A. Pinto,^4,5,6M. Valenzuela,¹A. Garcia,¹C. Ulloa,⁷R. Oses,^8,9,10,11B. H. Foing
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13972]
¹Instituto de Investigaciones Científicas y Tecnológicas, IDICTEC, Laboratorio de Investigacion de la Criosfera y Aguas, Universidad de Atacama, UDA, Copiapó, Chile
²Instituto de Investigación en Astronomía y Ciencias Planetarias, INCT, Universidad de Atacama, UDA, Copiapó, Chile
³Centre de Recherches Pétrographiques et Géochimiques, CRPG, Université de Lorraine, Nancy, France
⁴Departamento de Ciencias Geológicas, Universidad Católica del Norte, UCN, Antofagasta, Chile
⁵Millennium Institute of Astrophysics, MAS, Santiago, Chile
⁶Center for Excellence in Astrophysics and Associated Technologies, CATA, Santiago, Chile
⁷Centro Regional de Investigacion y Desarrollo Sustentable de Atacama, CRIDESAT, Universidad de Atacama, UDA, Copiapó, Chile
⁸Instituto de Investigación en Astronomía y Ciencias Planetarias, INCT, Universidad de Atacama, UDA, Copiapó, Chile
⁹International Lunar Exploration Working Group, ILEWG, EuroMoonMars, Noordwijk, The Netherlands
¹⁰Vrije Universiteit Amsterdam, VUA, Amsterdam, The Netherlands
¹¹Universiteit Leiden, Leiden, The Netherlands
Published by arrangement with John Wiley & Sons

In 2019, while launching a multidisciplinary research project aimed at developing the Puna de Atacama region as a natural laboratory, investigators at the University of Atacama (Chile) conducted a bibliographic search identifying previously studied geographic points of the region and of potential interest for planetary science and astrobiology research. This preliminary work highlighted a significant absence of local institutional involvement in international publications. In light of this, a follow-up study was conducted to confirm or refute these first impressions, by comparing the search in two bibliographic databases: Web of Science and Scopus. The results show that almost 60% of the publications based directly on data from the Puna, the Altiplano, or the Atacama Desert with objectives related to planetary science or astrobiology do not include any local institutional partner (Argentina, Bolivia, Chile, and Peru). Indeed, and beyond the ethical questioning of international collaborations, Latin-American planetary science deserves a strategic structuring, networking, as well as a road map at national and continental scales, not only to enhance research, development, and innovation, but also to protect an exceptional natural heritage sampling extreme environmental niches on Earth. Examples of successful international collaborations such as the field of meteorites, terrestrial analogs, and space exploration in Chile or astrobiology in Mexico are given as illustrations and possible directions to follow to develop planetary science in South America. To promote appropriate scientific practices involving local researchers, possible responses at academic and institutional levels will eventually be discussed.

Vera Rosenbush^a,b, et al. (>5)

Icarus (in Press) Open Access Link to Article [https://doi.org/10.1016/j.icarus.2025.116799]
^aAstronomical Observatory of Taras Shevchenko National University of Kyiv, 3 Observatorna St., Kyiv 04053, Ukraine
Copyright Elsevier