^1,2,3,4Wei Wu, ^2,3,4Yigang Xu, ⁵Zhaofeng Zhang
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2026.01.014]
¹School of Tourism and Geography, Shaoguan University, Shaoguan 512005 Guangdong, China
²State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 Guangdong, China
³Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), 511458 Guangdong, China
⁴School of Earth and Planetary Science, University of Chinese Academy of Sciences, Beijing 100049, China
⁵Research Center for Planetary Science, College of Geosciences, Chengdu University of Technology, Chengdu 610059 Sichuan, China
Copyright Elsevier

To constrain calcium isotopic fractionation during magma differentiation and its significance for planetary geochemistry, this study analyzed δ44/40Ca compositions of whole rocks, clinopyroxene, and plagioclase in mafic–ultramafic intrusions from two major large igneous provinces: the Tarim Large Igneous Province (Xiaohaizi intrusion) and the Emeishan Large Igneous Province (Panzhihua intrusion). Whole-rock δ44/40Ca ranges from 0.75 to 1.00 ‰ for Xiaohaizi and 0.82 to 0.97 ‰ for Panzhihua, while Pl δ44/40Ca varies from 0.69 to 1.07 ‰ (Xiaohaizi) and 0.78 to 0.99 ‰ (Panzhihua). Disequilibrium in selected samples is attributed to distinct geological processes: magma replenishment (Panzhihua) and crustal material assimilation (Xiaohaizi). For equilibrium samples, the Ca isotopic fractionation factor between Pl and melt (1000lnαPl-melt) exhibits no correlation with Pl An content and remains stable under specific temperature–pressure conditions for mafic to ultramafic plagioclase. By integrating this new dataset with published Δ44/40CaCpx-Pl data (including ab initio predictions and magmatic evolution model results), we determined 1000lnαPl-melt at 1273 K is −0.07 ± 0.10 ‰ (2SD, N = 28). This study clarifies the role of Pl in magmatic Ca isotopic fractionation, providing a reliable framework for tracing magma evolution and reconstructing early crust formation processes of terrestrial planets.

¹Jesse T. Gu, ¹Rebecca A. Fischer, ¹Lucy Jacobsen, ¹Michail I. Petaev
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2026.01.013]
¹Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA
Copyright Elsevier

Moderately volatile elements are depleted in the Earth relative to chondrites, but it remains uncertain to what extent these depletions of siderophile volatile elements are controlled by volatility versus core formation. Here, we report new metal–silicate partitioning experiments on Pb at pressures and temperatures up to 65 GPa and 5520 K, respectively. Combined with other moderately volatile elements, we use core formation models to show that homogeneous volatile accretion results in an overabundance of volatile siderophile elements relative to lithophile elements in the bulk Earth. Late volatile addition with metal–silicate equilibration at higher pressures and temperatures could potentially resolve this discrepancy by lowering bulk Earth abundances of volatile siderophile elements to be within uncertainty of the lithophile volatility trend. However, uncertainties in core formation parameters, element volatilities, volatile loss mechanisms, and the lithophile volatility trend complicate this interpretation. Our data support a relatively larger role for volatile depletion than for core formation in establishing the Pb content of the bulk silicate Earth.

^1,2Christopher A. Parendo, ¹Stein B. Jacobsen, ¹Michail I. Petaev
Earth and Planetary Science Letters 678, 119825 Link to Articles [https://doi.org/10.1016/j.epsl.2026.119825]
¹Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA 02138, United Kingdom
²Department of Earth & Planetary Sciences, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA
Copyright Elsevier

Calcium-aluminum-rich inclusions (CAIs), the oldest dated solids in the Solar System, preserve elemental and isotopic records of the thermal evolution of the early solar nebula—but some aspects, such as the processes driving large Ca-isotope variations, remain ambiguous. Previous studies observed isotopically light Ca in some CAIs, but whether these signatures arose from evaporation or condensation remains unresolved. We report new Ca-isotope and elemental data for 19 CAIs and 2 AOAs from the Allende meteorite and apply kinetic modeling to evaluate whether evaporation or condensation can account for the observed signatures. Our data confirm that CAIs exhibiting volatility-related REE fractionation have lighter Ca-isotope compositions than those with unfractionated REEs. Modeling demonstrates that evaporation cannot produce materials with both isotopically light Ca and near-chondritic Al/Ca ratios, requiring condensation as the cause of the observed Ca-isotope variations. Notably, modeled rates indicate that condensation occurred rapidly, over ∼10-1000 days, much faster than secular cooling of the solar nebula. These results constrain CAI thermal histories and offer insight into high-temperature processes in the early Solar System.

^1,2,3Emilie T. Dunham,¹Ming-Chang Liu,^3,4Aman Burman,³Fatima Jorge-Chavez,³Danielle Leuer,⁵Ashley K. Herbst,⁶François L. H. Tissot,³Kevin D. McKeegan
The Astrophysical Journal Supplement Series, 282, 11 Open Access Link to Article [DOI 10.3847/1538-4365/ae1835]
¹Lawrence Livermore National Laboratory, Livermore, CA 94550, USA​; dunham12@llnl.gov
²Earth, Planetary, and Space Sciences Department, University of California Los Angeles, Los Angeles, CA 90025, USA​
³Earth and Planetary Sciences Department, University of California Santa Cruz, Santa Cruz, CA 95064, USA​
⁴The California Institute of Technology, Pasadena, CA 91125, USA​
⁵School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85281, USA
⁶The Isotoparium, Division of Geological and Planetary Sciences, The California Institute of Technology, Pasadena, CA 91125, USA

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

^1,2Niccolò Magnani,^2,3Enrico Mugnaioli,²Sofia Lorenzon,⁴Lidia Pittarello,⁵Tatiana E. Gorelik,^2,3Matteo Masotta,^2,3Luigi Folco
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70094]
¹Dipartimento di Scienze dell’Ambiente e della Terra, Universita di Milano-Bicocca, Milan, Italy
²Dipartimento di Scienze della Terra, Universita di Pisa, Pisa, Italy
³Centre for Instrument Sharing of the University of Pisa, Pisa, Italy
⁴Mineralogisch-Petrographische Abteilung, Naturhistorisches Museum, Vienna, Austria
⁵Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Juelich, Juelich, Germany
Published by arrangemetn with John Wiley & Sons

Libyan Desert Glass (LDG) is an ~29 million years old, silica-rich glass found inWestern Egypt. Whether this glass formed in an impact cratering context associated withthe hypervelocity collision of a cometary/asteroidal body or radiative heating during anairburst is debated. Determination of the formation temperatures and pressures of raremineral components in LDG can provide key petrogenetic constraints on its origin. Here,we report the occurrence of a zircon inclusion, whose textural, chemical, andcrystallographic features point to a rapid formation during solidification of the silica-richLDG melt. The study was conducted combining dual beam microscopy, transmissionelectron microscopy, energy-dispersive X-ray spectroscopy, and three-dimensional electrondiffraction. The inclusion is a few tens of micrometer in size and consists of dendriticbranches of zircon arranged in a reticulate-cruciform texture. The high-silica glass fillinginterstices between dendrites have longer chemical bonds compared to matrix glass, asindicated by electron pair distribution function analysis, and is enriched in Al 2 O 3 . The lackof incongruent melt products (ZrO 2 , SiO 2 ) suggests that the inclusion formed during coolingfrom supraliquidus conditions, by dynamic crystallization from an (immiscible) undercooledliquid droplet. Such droplet would derive from shock-induced melting of a precursor zircongrain, possibly mixed with the SiO 2 -rich liquid formed by melting of the LDG precursormaterial. The formation model proposed for this inclusion does not allow us to discriminatebetween the two genetic processes proposed for LDG, but sets a new minimum to theliquidus temperature of the corresponding chemical system of ~2250°C.

¹M. J. Burchell,²R. C. Ogliore,¹P. J. Wozniakiewicz
Meteoritics & Planetary Sciences (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70090]
¹Centre for Astrophysics and Planetary Science, School of Engineering, Mathematics and Physics
²University of Kent,Canterbury, Kent, UK2 Department of Physics, University of Central Florida, Orlando, Florida, USA
Published by arrangement with John Wiley & Sons

The desire to sample material from the interior of Io, by flying through its volcanicplumes, requires consideration of the flyby speed and the types of sample collection techniquesthat can be utilized. Low speed collection (1–2.5 km s1) would require an orbit around Io itself,which is unlikely due to the accumulated radiation dose that would be experienced. Moderatecollection speeds (7–9 km s1) are possible for flybys of Io arising from either a single passagethrough the Jovian system (followed by sample return) or a carefully selected orbit aroundJupiter that has the main purpose of visiting Io. However, even if they include an Io closepassage, most Jovian mission orbit concepts also include and even prioritize other scienceobjectives, resulting in orbits with Io collection speeds of around 17–19 km s1 (or greater).Depending on the speed and collector material, the peak shock pressures during collection maythus range from 5 to hundreds of GPa for impacts on solid, nonporous media, with pressuresfrom 0.01 to 5 GPa for impacts on low-density aerogels. These shock pressures are calculatedherein for a range of Io encounter speeds and collector types, and the degree of sample captureand impact processing are estimated. While capture of material is shown to be possible at speedsup to 10 km s1, permitting both in situ analysis or sample return to Earth, above these speedsretention of significant amounts of unvaporized material in a collector is not viable.

^1,2Birger Schmitz,³Yue Cai,^2.4Shiyong Liao,⁵Victoriano Pujalte,³Ting Ruan,⁶Robert P. Speijer,^7,8Ellen Thomas
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.70082]
¹Astrogeobiology Laboratory, Department of Physics, Lund University, Lund, Sweden
²Key Laboratory of Planetary Sciences, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing, China
³State Key Laboratory of Paleobiology and Stratigraphy, Nanjing Institute of Geology and Paleontology, Chinese Academy ofSciences, Nanjing, China
⁴Chinese Academy of Sciences, Center for Excellence in Comparative Planetology, Hefei, China
⁵Department of Geology, Faculty of Science and Technology, University of the Basque Country, Bilbao, Spain
⁶Department of Earth and Environmental Sciences, KU Leuven, Leuven, Belgium
⁷Department of Earth and Planetary Sciences, Yale University, New Haven, CT, USA
⁸Department of Earth and Environmental Sciences, Wesleyan University, Middletown, CT, USA
Published by arrangement with John Wiley & Sons

Almost 10 years have passed since microtektites and microkrystites were reportedfor the Paleocene–Eocene (P–E) boundary in drill cores and outcrop in New Jersey and inODP Hole 1051B in the western North Atlantic. The glassy spherules were interpreted toreflect an impact trigger for the Paleocene–Eocene Thermal Maximum (PETM). Since then,many detailed studies of sediment strata across the P–E boundary worldwide have beenperformed, but so far, no additional reports of impact spherules have been published.Negative results usually are not published, but here we report a lack of success in finding suchspherules at the P–E boundary in ODP Hole 1051B. We searched 90 g of sediment from thesame interval in the same core from which 56 impact spherules >63 lm were previouslyreported from 35 g of sediment, but did not find microtektites or microkrystites. We also didnot find impact spherules in a detailed search of 2.3 kg of sediment from the P–E boundary inthe Zumaia section (Spain), where the boundary is marked by a minor iridium anomaly. Inaddition, we did not find such spherules in P–E boundary sediment from sections in Europeand the Middle East nor in drill cores from the southern Atlantic. We urge the researchcommunity to report further both negative and positive results on this issue in order toelucidate the envisioned P–E boundary impact event.

¹Jingyou Chen, ²Shaolin Li, ³Shiyong Liao, ⁴Jian Chen, ⁵Alexander Nemchin, ⁶Katherine H. Joy, ⁷Xiaochao Che, ³Weibiao Hsu, ⁸Menghua Zhu
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2026.01.007]
¹State Key Laboratory of Deep Earth Processes and Resources, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
²Astronomical Research Center, Shanghai Science and Technology Museum, Shanghai, China
³CAS Center for Excellence in Comparative Planetology, Purple Mountain Observatory, Nanjing 210034, China
⁴Shandong Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai 264209, China
⁵School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
⁶Department of Earth and Environmental Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK
⁷The Beijing SHRIMP Center, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China
⁸State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Macau
Copyright Elsevier

The increasing identification of magnesian anorthosites (MAN) in lunar meteorites, along with inferences from remote sensing techniques, has intensified research interest in understanding their role in lunar crust formation. However, the lack of robust geochronological constraints for MAN impeded our comprehension of the timeline of crustal evolution. The lunar feldspathic breccia meteorite, Northwest Africa (NWA) 11479, is composed primarily of Mg-rich, KREEP-poor (K, rare earth elements, and P) highland lithic fragments, predominantly consisting of magnesian anorthositic lithologies (including anorthosite noritic/troctolitic anorthosites, and the associated magnesian granulites). The close chemical match between the bulk rock and lunar remote sensing data supports a farside origin, providing evidence for the presence of MAN in the Feldspathic Highlands Terrane (FHT).
Zircon and apatite grains have been discovered within the small Mg-rich anorthositic clasts in NWA 11479. Notably, the occurrence of these highly evolved accessory minerals contrasts with the depletion of incompatible trace elements in the coexisting silicates, suggesting their formation via interactions between the anorthositic crust and a later-stage KREEPy metasomatic melt. In-situ U-Pb isotopic analysis of the zircon and apatite yields a well-defined discordia line, with an upper intercept date of 4328 ± 9 Ma (2σ), and a lower intercept date of 140 ± 64 Ma (2σ). The younger age likely reflects a more recent impact event, whereas the upper intercept is consistent with both the concordant U-Pb zircon date (4327 ± 12 Ma, 2σ) and the weighted average 207Pb/206Pb date of the zircon and apatite (4326 ± 8 Ma, 2σ). This ∼ 4.33 Ga age is interpreted as the timing of metasomatism responsible for the formation of the zircon and apatite, or an impact event. Importantly, this age obtained from the putative-origin meteorite coincides with the period (4.3–4.35 Ga) of the active secondary magmatism recorded in nearside-collected Apollo samples, the proposed formation age of the giant South Pole–Aitken (SPA) basin. These temporal correlations suggest that this epoch represents a major phase of global reworking of the primordial lunar crust, likely driven by the overturn of mantle cumulates and further intensified by basin‑scale impact events, or both.

¹Mingming Zhang, ^1,3Kohei Fukuda, ²Michael J. Tappa, ²William O. Nachlas, ²²Bil Schneider, ⁴Makoto Kimura, ¹Kouki Kitajima, ²Ann M. Bauer, ¹Noriko T. Kita
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2025.12.056]
¹WiscSIMS, Department of Geoscience, University of Wisconsin–Madison, Madison, WI 53706, USA
²Department of Geoscience, University of Wisconsin–Madison, Madison, WI 53706, USA
³Graduate School of Science, The University of Osaka, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
⁴National Institute of Polar Research, Meteorite Research Center, Midoricho 10-3, Tachikawa, Tokyo 190-8518, Japan
Copyright Elsevier

Chondrules, ferromagnesium spherules prevalent in undifferentiated extraterrestrial materials, are the main high-temperature products of the protoplanetary disk. Relict minerals within them directly record precursor compositions and thermal histories, offering critical constraints on the long-debated chondrule heating mechanism. We identified pervasive relict refractory anorthites in Al-rich chondrules (bulk Al2O3 ≥10 wt%, ARCs) from pristine carbonaceous chondrites. These anorthites form rims around relict spinel aggregates or intergrow with high-Ca pyroxene/olivine relics, indicating preferential recycling of anorthite-rich inclusions during outer-disk chondrule heating events over more abundant melilite-rich ones. The wide occurrence of relict anorthite, which can be readily melted or dissolved in chondrule melts, suggests these ARCs were most likely formed by one-time crystallization. Thus, their Al-Mg ages of ∼2.0–2.5 Ma after CAIs imply refractory materials were continuously involved over nearly the entire period of chondrule formation. Additionally, we infer that a portion of co-formed iron-poor ferromagnesium chondrules must have similarly escaped completely remelting by subsequent intense heating events in the same reservoirs. These findings suggest that the intense heating events that lead to carbonaceous chondrule formation are localized and infrequent, aligning with mechanisms like bow shocks, lightning discharges, and impact jetting but not the large-scale nebular shocks.

^1,2William F. McDonough
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2025.12.060]
¹Advanced Institute for Marine Ecosystem Change (WPI-AIMEC), Department of Earth Sciences and Research Center for Neutrino Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
²Department of Geology, University of Maryland, College Park, MD 20742, USA
Copyright Elsevier

One in every two atoms in the Earth, Mars, and the Moon is oxygen; it is the third most abundant element in the solar system. The oxygen isotopic compositions of the terrestrial planets are different from those of the Sun and demonstrate that these planets are not direct compositional analogs of the solar photosphere. Likewise, the Sun’s O/Fe, Fe/Mg and Mg/Si values are distinct from those of inner solar system chondrites and terrestrial planets. These four elements (O, Fe, Mg, Si) make up 90% to 94% by mass (and atomic %) of the rocky planets, and their abundances are determined uniquely using geophysical, geochemical, and cosmochemical constraints.

The rocky planets likely grew rapidly (with    10 million years) from large populations of planetesimals, most of which were differentiated, having a core and a mantle, before being accreted. Planetary growth in the early stages of protoplanetary disk evolution was rapid and was only partially recorded by the meteoritic record. The noncarbonaceous meteorites (NC) provide insights into the early history of the inner solar system and are used to construct a framework for how the rocky planets were assembled. NC chondrites have chondrule ages that are two to three million years younger than  (the age of calcium–aluminum inclusions, CAI), documenting that NC chondrites are middle- to late-stage products of solar system evolution.

The composition of the Earth, its current form of mantle convection, and the amount of radiogenic power that drives its engine remain controversial topics. Earth’s dynamics are driven by primordial and radiogenic heat sources. Measurement of the Earth’s geoneutrino flux defines its radiogenic power and restricts its bulk composition. Using the latest data from the KamLAND and Borexino geoneutrino experiments affirms that the Earth has   20 TW of radiogenic power and sets the proportions of refractory lithophile elements in the bulk silicate Earth at   2.7 times that in CI chondrites. The bulk Earth and the bulk Mars are enriched in refractory elements about 1.9 times that of the CI chondrites. Earth is more volatile-depleted and less oxidized than Mars.