Meteoritics & Planetary Science最新文献

{"title":"The 40K-K dating system: 1. Improving data interpretation using new model calculations","authors":"Farshid Nozarian,&nbsp;Suzette Timmerman,&nbsp;Ingo Leya","doi":"10.1111/maps.70201","DOIUrl":"https://doi.org/10.1111/maps.70201","url":null,"abstract":"<p>The ⁴⁰K-K cosmic-ray exposure (CRE) dating system offers a promising method for determining exposure ages of iron meteorites by combining the radioactive cosmogenic ⁴⁰K with the stable cosmogenic isotopes ³⁹K and ⁴¹K. However, earlier applications relied on semi-empirical production models and inconsistent analytical data sets, limiting their reliability. This study presents a comprehensive reassessment of the ⁴⁰K-K and ⁴He/²¹Ne system using state-of-the-art model calculations. Production rates of ³⁹K, ⁴⁰K, and ⁴¹K were simulated with the GEANT4–INCL++6 framework, incorporating updated excitation functions and fully considering depth-dependent shielding effects. The resulting model yields physically robust relationships between K isotopes and noble gas shielding proxies, such as ⁴He/²¹Ne. In addition to revisiting the classical approach used by Voshage and co-workers, we introduce two new alternative strategies for calculating CRE ages: a two-component mixing model and a native-K correction approach that mitigates contamination effects. Overall, these developments establish a more accurate and physically consistent framework for future applications of the ⁴⁰K–K system in cosmochemistry and studies of galactic cosmic rays.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"61 9","pages":"2187-2200"},"PeriodicalIF":3.2,"publicationDate":"2026-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.70201","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148943611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Origin and formation of a chondritic xenolith in Krymka (LL3.2, breccia): Indications for a late formation of the accretionary breccia","authors":"Aelita Girich,&nbsp;Addi Bischoff,&nbsp;Samuel Ebert,&nbsp;Kazuhide Nagashima,&nbsp;Andreas Morlok,&nbsp;Harald Hiesinger,&nbsp;Jasper Berndt","doi":"10.1111/maps.70195","DOIUrl":"https://doi.org/10.1111/maps.70195","url":null,"abstract":"<p>An unusual chondritic xenolith was found in two sequentially prepared thin sections of a sample from the Krymka (LL3.2) chondrite. The xenolith has a rounded, slightly deformed shape of about 5 mm in apparent diameter and is partially surrounded by a double rim made of an inner fine-grained silicate-rich rim and an outer sulfide-rich rim. The xenolithic inclusion is characterized by partially equilibrated mineral constituents, a recrystallized chondritic texture with relic chondrules, and a high abundance of CAIs (0.11 vol%). Within the core of the xenolith, olivine and low-Ca pyroxene are the most abundant mineral phases, and randomly analyzed grains by grid analysis revealed mean compositions of Fa_9.8±5.5 and Fs_7.2±4.4Wo_2.9±2.2 for olivine and low-Ca pyroxene, respectively. Within the entire clast, a feldspar-normative mesostasis is embedding all constituents, indicating partial melting of the xenolith, probably during impact metamorphism. Thus, the xenolithic clast is very likely an impact melt rock. Infrared (IR) spectroscopic studies revealed the dominance of olivine and low-Ca pyroxene in the obtained spectra from the fine-grained silicate-rich rim of the xenolith. Oxygen isotope analyses by SIMS show that, in the three-oxygen isotope diagram, most individual olivine grains from the xenolith plot within the field of bulk ordinary chondrites and their chondrules, except for three olivines: Two grains from the xenolith's core (Δ¹⁷O = −1.6 ± 0.5‰ and −2.4 ± 0.5‰) and one olivine from the rim (Δ¹⁷O = −6.5 ± 0.4‰) show significant ¹⁶O enrichments. The chondritic impact melt rock studied here clearly demonstrates that this xenolithic clast formed prior to the Krymka parent body accretion within another pre-existing chondritic parent body. While previous studies have discussed a potential late-stage accretion of large Krymka constituents, the components within the apparent first-generation parent body experienced thermal annealing, and, subsequently, the xenolith suffered partial melting due to a shock event that probably caused this fragment to be ejected from its first-generation parent body.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"61 8","pages":"2016-2047"},"PeriodicalIF":3.2,"publicationDate":"2026-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.70195","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148719296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effects of shock process and terrestrial weathering on mercury isotopes in meteorites","authors":"Yan Fan,&nbsp;Deze Liu,&nbsp;Shijie Li,&nbsp;Xiangdong Li,&nbsp;Shen Liu,&nbsp;Dehan Shen,&nbsp;Qing-Zhu Yin","doi":"10.1111/maps.70175","DOIUrl":"https://doi.org/10.1111/maps.70175","url":null,"abstract":"<p>This study assesses mercury (Hg) concentrations and their isotopic compositions in Antarctic chondrites, desert chondrites, and drilled samples from the Jilin chondrite (H5). Desert chondrites show mercury concentrations between 2.2 ng g⁻¹ and 156.8 ng g⁻¹, with δ²⁰²Hg ranging from −3.69‰ to 1.19‰. Δ¹⁹⁹Hg and Δ²⁰¹Hg vary from −0.23‰ to −0.02‰ and −0.2‰ to 0.02‰, respectively, showing a weak positive correlation among these parameters (slope 0.74 ± 0.24, <i>R</i>² = 0.46). These Hg concentrations and isotopic composition data of desert chondrites indicate that Hg in desert chondrites has been altered due to terrestrial processes in addition to evaporation loss during its terrestrial residence period. Antarctic chondrites exhibit mercury concentrations from 8.0 ng g⁻¹ to 3940.8 ng g⁻¹, with δ²⁰²Hg from −2.51‰ to 1.16‰. Δ¹⁹⁹Hg and Δ²⁰¹Hg range from −0.83‰ to −0.05‰ and −0.71‰ to 0.10‰, with a significant correlation (slope 0.93 ± 0.15, <i>R</i>² = 0.76), likely influenced by Antarctic snow that has experienced significant photochemical processes during atmospheric mercury depletion events (AMDEs) and has elevated mercury content (such as drifted snow). Jilin meteorite's δ²⁰²Hg, Δ¹⁹⁹Hg, and Δ²⁰¹Hg vary between −3.74‰ to −1.79‰, −0.12‰ to 0.09‰, and −0.12‰ to −0.01‰, respectively. A weak positive correlation between Δ¹⁹⁹Hg and Δ²⁰¹Hg (slope 1.45 ± 0.28, <i>R</i>² = 0.67) suggests localized Hg evaporation due to shock processes on the parent body; however, Hg isotopic heterogeneity from nebular or parent body processes cannot be excluded. Terrestrial weathering and shock events could alter Hg content and isotopic compositions in chondrites, challenging their use as accurate indicators of Hg's cosmochemical behavior.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"61 8","pages":"1709-1728"},"PeriodicalIF":3.2,"publicationDate":"2026-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148719225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nanoscale space weathering features in mature lunar soil revealed by TEM and APT","authors":"Jennika Greer,&nbsp;Alexander M. Kling,&nbsp;Luke Daly,&nbsp;Dieter Isheim,&nbsp;David N. Seidman,&nbsp;Michelle S. Thompson,&nbsp;Philipp R. Heck","doi":"10.1111/maps.70196","DOIUrl":"https://doi.org/10.1111/maps.70196","url":null,"abstract":"<p>Space weathering significantly alters the optical, chemical, and structural properties of lunar regolith at micro- and nanoscales; yet detailed nanoscale variability within individual soils remains underexplored. Here we apply transmission electron microscopy (TEM) and atom probe tomography to four mineral grains (olivine, ilmenite, and two agglutinitic grains) from mature Apollo 17 soil 79221, characterizing solar wind-induced damage, vesiculation, nanophase Fe formation, and volatile retention with nanometer resolution. Our analyses reveal pronounced heterogeneity in vesicle morphology, nanophase Fe abundance, and volatile content that varies with mineralogy and exposure history. Oxygen depletion near grain surfaces indicates sputtering effects. Beyond confirming nanoscale heterogeneity, our coordinated analyses resolve, by APT, the Fe-depleted halos around npFe⁰ in mature ilmenite that we previously documented with the same technique in submature Apollo 17 ilmenite. We identify impact-melt quench textures that contribute non-weathering npFe⁰ to agglutinitic grains, and find a thick damage rim with few npFe⁰ in Mg-rich olivine accumulates. TEM observations of elongated, linear vesicles aligned parallel to ilmenite blade margins within a bladed agglutinitic grain further suggest crystallographic rather than directional control of vesicles in ilmenite inclusions. We also establish that vesicles distort APT reconstructions and degas during field evaporation, complicating quantitative inventories of npFe⁰ and volatiles in space-weathered grains.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"61 8","pages":"2048-2072"},"PeriodicalIF":3.2,"publicationDate":"2026-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.70196","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148719231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact provenance and age of a unique basalt found in Apollo 12 regolith","authors":"C. Deligny,&nbsp;M. J. Whitehouse,&nbsp;R. E. Merle,&nbsp;H. Jeon,&nbsp;A. A. Nemchin,&nbsp;B. L. Jolliff","doi":"10.1111/maps.70204","DOIUrl":"https://doi.org/10.1111/maps.70204","url":null,"abstract":"<p>Basaltic sample 12032,366-18 from the Apollo 12 landing site is distinct among basalts collected at this site, other Apollo landing sites, and lunar meteorites in terms of its age, bulk rock composition, and isotopic composition. We present new Pb isotopic data obtained by in situ Secondary Ion Mass Spectrometry on multiple mineral phases in 12032,366–18. These data yield a crystallization age of 3400 ± 16 Ma, older than other Apollo 12 basalts, which crystallized between ~3.1 and 3.3 Ga. The initial Pb isotopic composition plots slightly below the mixing line between KREEP (an incompatible-element-rich lunar reservoir enriched in K, rare Earth elements, and P) and a depleted lunar mantle reservoir with low-μ (<i>μ</i> = ²³⁸U/²⁰⁴Pb) value. The bulk composition is characterized by elevated incompatible trace element abundances, including high thorium (~7 ppm), relatively high FeO, and intermediate Ti contents, distinguishing it from other Apollo 12 and lunar basalts. Although it shares some affinities with Apollo KREEP basalts, its higher bulk rock Al₂O₃ content and the presence of olivine are more consistent with high-Al basalts. Together, 12032,366–18 is not indigenous to the Apollo 12 landing site but instead represents material transported from a distant source region, most plausibly within western Oceanus Procellarum, potentially linked to the Kepler impact crater region.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"61 8","pages":"2073-2085"},"PeriodicalIF":3.2,"publicationDate":"2026-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.70204","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148719233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mineralogy, mineral chemistry, and redox equilibria in ten aggregate particles from asteroid Bennu","authors":"K. Righter,&nbsp;J. Gorce,&nbsp;L. Le,&nbsp;K. Thomas-Keprta,&nbsp;Z.E. Wilbur,&nbsp;L.P. Keller,&nbsp;Z. Gainsforth,&nbsp;T.J. McCoy,&nbsp;T.J. Zega,&nbsp;S.S. Russell,&nbsp;H.C. Connolly Jr.,&nbsp;D.S. Lauretta","doi":"10.1111/maps.70182","DOIUrl":"https://doi.org/10.1111/maps.70182","url":null,"abstract":"<p>Examination of 10 Bennu aggregate particles has revealed the presence of many phases which taken together can provide constraints on the oxygen fugacity (<i>f</i>O₂) of Bennu samples. Phyllosilicates (saponite and serpentine), carbonates, oxides (magnetite, chromite), sulfides (pyrrhotite, pentlandite), phosphate (hydroxyapatite, Na-Mg-phosphate), and phosphides (schreibersite, andreyivanovite) all occur in most Bennu particles. The Bennu samples have experienced a high degree of aqueous alteration leaving only &lt;1% of the original mineralogy unaltered. However, both the precursor anhydrous and alteration phases can present different constraints on <i>f</i>O₂. Precursor phases include olivine, pyroxene, spinel, hibonite, chromite, phosphide, very rare Fe-Ni metal, apatite, and possibly MgS and MnS, all of which are typically &lt;25 μm in size. Alteration phases include phyllosilicates, carbonates, magnetite, sulfides, sulfates, phosphates, chlorides, and fluorides. Detailed calculations of <i>f</i>O₂ rely on having quantitative electron microprobe analyses of the phases involved in equilibria amongst both the precursor and alteration phases. In general, the absence of Fe-Ni metal, coupled with the stability of the Fe₃O₄ component in chromite, places a lower limit on the <i>f</i>O₂. Concomitantly, the absence of Fe sulfates places an upper limit on <i>f</i>O₂. Altogether, the textures, mineral compositions, and calculations suggest that some components in the Bennu samples (chondrules, inclusions) may have originally equilibrated at <i>f</i>O₂ well below the iron-wüstite buffer but then experienced higher <i>f</i>O₂ near or higher than the fayalite-magnetite-quartz (FMQ) buffer during aqueous alteration that produced coarser grained oxidized assemblages.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"61 8","pages":"1905-1927"},"PeriodicalIF":3.2,"publicationDate":"2026-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.70182","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148719271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluating maturity of organic matter in hydrated C1 and CM-like clasts and a dehydrated clast within a polymict eucrite and a howardite","authors":"Swarna Prava Das,&nbsp;Alessandro Maturilli,&nbsp;Aurélie Van den Neucker,&nbsp;Markus Patzek,&nbsp;Dipak Kumar Panda,&nbsp;Gopal K. Pradhan,&nbsp;Guneshwar Thangjam,&nbsp;Surya Snata Rout","doi":"10.1111/maps.70183","DOIUrl":"https://doi.org/10.1111/maps.70183","url":null,"abstract":"<p>Volatile-rich xenolithic clasts in different types of brecciated meteorites represent unique pristine solar system material. This study investigates the maturity and thermal history of organic matter using Raman spectroscopy and aqueous alteration effects using infrared spectroscopy in the matrix of 15 volatile-rich clasts (C1 and CM-like) present in a polymict eucrite (NWA 7542) and a howardite (Sarıçiçek). Most of the studied C1 and CM-like clasts show similar maturity of organic matter as CI chondrites and CM chondrites, respectively. One CM-like clast from the polymict eucrite NWA 7542 shows Raman spectral signatures of heating after aqueous alteration, and another C1 and a CM-like clast from the howardite Sarıçiçek exhibit unique Raman spectral properties probably related to differences in accreted precursor organics compared to CI and CM-chondrites. One olivine-rich, unclassified clast has a high concentration of fayalitic olivine in its matrix, similar to oxidized CV chondrites and other features similar to CM- or C2 chondrites. Various evidence shows that this clast was heated up to 700–800 °C post aqueous alteration followed by the formation of fayalitic olivine during a metasomatic alteration process. Peak metamorphic temperature (PMT) estimated using different thermometric approaches does not provide reliable data for clasts altered at low temperatures (&lt;200 °C).</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"61 8","pages":"1965-1993"},"PeriodicalIF":3.2,"publicationDate":"2026-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.70183","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148719304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reassessing the organic carbon budget in the Murchison meteorite through an extraction–recovery mass-balance approach","authors":"Hina Dohi,&nbsp;Minako Hashiguchi,&nbsp;Koichi Mimura","doi":"10.1111/maps.70173","DOIUrl":"https://doi.org/10.1111/maps.70173","url":null,"abstract":"<p>A substantial fraction of organic carbon in carbonaceous chondrites has long been described as “missing,” reflecting incomplete recovery and limited resolution of operationally defined organic components. Here, we present a quantitative reassessment of the carbon budget in the Murchison meteorite using an integrated extraction–recovery mass-balance approach that constrains the distribution of carbon among operational fractions. Insoluble organic matter accounts for 69% ± 1.4% of total carbon, while acid-hydrolyzable organic matter (AOM) constitutes 15% ± 2.9%, representing a carbon pool comparable to soluble organic matter (SOM, 14% ± 2.7%). Carbonate-derived carbon accounts for 2% ± 2.0% of the total carbon inventory. The total recovered organic carbon reaches 88% ± 1.4% of bulk carbon. Carbon previously regarded as “missing” can be quantitatively reassigned to specific organic fractions, including uncollected AOM (7%) and SOM (2%), substantially reducing the previously unconstrained carbon fraction. Replicate analyses of three independently processed subsamples yield consistent residue-based carbon partitioning, supporting the robustness of the mass-balance framework. These results indicate that much of the missing carbon reflects incomplete recovery in analytical workflows rather than an unidentified reservoir, refining the organic carbon inventory of Murchison and providing a framework for reassessing carbon partitioning in primitive planetary materials.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"61 8","pages":"1729-1741"},"PeriodicalIF":3.2,"publicationDate":"2026-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.70173","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148719346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The role of composition in the spectral evolution of carbonaceous asteroids as informed by Bennu sample return","authors":"Ralph E. Milliken,&nbsp;Takahiro Hiroi,&nbsp;Victoria E. Hamilton,&nbsp;Cody D. Schultz,&nbsp;Ed A. Cloutis,&nbsp;Hannah H. Kaplan,&nbsp;Melissa K. Kontogiannis,&nbsp;Nathalia Vega-Santiago,&nbsp;Dani N. DellaGiustina,&nbsp;Harold C. Connolly Jr.,&nbsp;Dante S. Lauretta","doi":"10.1111/maps.70179","DOIUrl":"https://doi.org/10.1111/maps.70179","url":null,"abstract":"<p>Near-Earth rubble-pile asteroids Bennu and Ryugu are part of the carbonaceous taxonomic complex (C-complex), and samples returned from both bodies resemble the most aqueously altered carbonaceous chondrites. However, telescopic and spacecraft visible–near infrared (VIS–NIR) reflectance spectra of Ryugu exhibit a red (positive) spectral slope, whereas Bennu has a blue (negative) spectral slope characteristic of the rare B-type subclass of asteroids. The asteroid spectra also suggest different levels of hydration, with Ryugu dominated by OH and Bennu containing spectral evidence of more H₂O. To understand what causes these differences, we acquired VIS–NIR reflectance data (~0.3–5 μm) from a variety of Bennu samples over spatial scales of 100 μm to several millimeters. No single sample reproduces the average spectral properties of Bennu, but by evaluating samples of different petrology and physical states—groups of particles, isolated particles, and larger stones—we demonstrate that primary composition, and highly hydrated Mg-rich phosphate in particular, plays a strong role in controlling the spectral slope and average hydration absorption strength of Bennu materials. Bennu and Ryugu may be dominated by different lithologies originating from different regions of a common planetesimal, thus explaining their different spectral evolution. The spectral characteristics of B-type asteroids, particularly those with blue slopes at near-infrared wavelengths and broad hydration features at ~3 μm, may indicate the presence of Mg phosphate and thus a history of complex fluid–rock interactions relevant to prebiotic chemistry.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"61 8","pages":"1875-1904"},"PeriodicalIF":3.2,"publicationDate":"2026-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.70179","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148719189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stardust Mine: A 2024 gabbroic shergottite from Arizona, USA","authors":"Jennifer T. Mitchell,&nbsp;Natasha R. Stephen,&nbsp;Zsuzsanna P. Allerton,&nbsp;Weiming Ding,&nbsp;Xin-Yuan Zheng","doi":"10.1111/maps.70181","DOIUrl":"https://doi.org/10.1111/maps.70181","url":null,"abstract":"<p>This study provides an initial characterization of Stardust Mine, a fresh gabbroic enriched shergottite collected in Arizona, USA, in September 2024 and is the first Martian meteorite to be unequivocably collected on US soil. Analysis was conducted on the type specimen and finds that Stardust Mine is composed of equal proportions of pyroxene and maskelynite, with large Fe-Ti oxides and phosphates. Ti/Al ratios and two-pyroxene thermometry of the most primitive pyroxenes (Mg# &gt;57), inferred to represent preplagioclase pyroxene crystallization, give an estimated minimum initial crystallization depth of ~40 km at ~1140°C. Sector zoning is restricted to these pyroxenes and may have developed through magmatic undercooling in response to magma ascent before storage in a staging chamber in the volcanic system. Pyroxene and plagioclase cocrystallized for almost the entirety of the crystallization sequence with evolving melt compositions, followed by phosphates and Fe-Ti oxides. Ilmenite-titanomagnetite pairs and D(Cr)_pyroxene suggest the magma was relatively oxidized (<i>f</i>O₂ ΔQFM −1.3) compared with other shergottites. Accumulation and crystal settling in a sill, dyke, or intracrustal magma chamber allowed the development of a shape-preferred orientation and decomposition of metastable pyroxenes to three-phase symplectites. Stardust Mine represents a highly fractionated lithology that extends the range of high-Al basaltic shergottites to ~8 wt% Al. Our analysis does not find a clear pairing with shergottites in literature in lieu of radiogenic isotope data, and Stardust Mine may therefore represent a previously unsampled lithology.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"61 8","pages":"1826-1846"},"PeriodicalIF":3.2,"publicationDate":"2026-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.70181","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148719242","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}