Meteoritics & Planetary Science最新文献

{"title":"Oued Chebeika 002: A new CI1 meteorite linked to outer solar system bodies","authors":"J. Gattacceca,&nbsp;M. Gounelle,&nbsp;B. Devouard,&nbsp;J.-A. Barrat,&nbsp;L. Bonal,&nbsp;A. J. King,&nbsp;C. Maurel,&nbsp;P. Beck,&nbsp;M. Roskosz,&nbsp;J.-C. Viennet,&nbsp;D. Mukherjee,&nbsp;N. Dauphas,&nbsp;P. R. Heck,&nbsp;T. Yokoyama,&nbsp;K. López García,&nbsp;O. Poch,&nbsp;O. Grauby,&nbsp;C. S. Harrison,&nbsp;V. Vinogradoff,&nbsp;P. Vernazza,&nbsp;S. Tikoo,&nbsp;V. Vidal,&nbsp;P. Rochette,&nbsp;D. AuYang,&nbsp;D. Borschneck,&nbsp;J. Juraszek,&nbsp;B. Clark","doi":"10.1111/maps.14359","DOIUrl":"https://doi.org/10.1111/maps.14359","url":null,"abstract":"<p>CI1 chondrites are rare meteorites with high scientific value. In fact, they are the most chemically primitive meteorites and show evidence of intense parent-body aqueous alteration. They also share strong similarities with samples from Ryugu and Bennu asteroids returned by the JAXA Hayabusa2 and NASA's OSIRIS-REx missions. In this work, we present a detailed study of the Oued Chebeika 002 meteorite, a ~420 g CI1 chondrite found in Morocco in 2024. We describe its petrography, texture, and mineralogy, with a focus on clay mineralogy. We provide the bulk and mineral chemical composition, as well as the bulk oxygen, iron, and chromium isotopic compositions. Spectroscopic properties were studied by means of infrared and Raman spectroscopies. We also measured the density, grain density and magnetic properties. Our results confirm that Oued Chebeika 002 is a CI1 chondrite, with close similarities to the other five know CI1 chondrites, and samples from Ryugu and Bennu asteroids. Several lines of evidence indicate that Oued Chebeika 002 has suffered no significant terrestrial alteration. It is more pristine in that regard than Alais, Orgueil and Ivuna CI1 chondrites, and more similar to samples from asteroids Ryugu and Bennu. Subtle differences exist between Oued Chebeika 002 and other CI1 chondrites that cannot be accounted for by terrestrial alteration of the latter. For instance, olivine and calcite were not observed. It is also noteworthy that the magnetic mineral assemblage of Oued Chebeika 002 is significantly different from that of Alais, Ivuna and Orgueil, but undiscernible from that of Ryugu samples. Chromium and iron isotopic composition of Oued Chebeika 002 confirms that CI1 chondrites, like Ryugu samples, are distinct from meteorites belonging to the non-carbonaceous and carbonaceous isotopic groups and may have originated from the same region where ice giant planets and Oort Cloud comets were formed.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 7","pages":"1441-1479"},"PeriodicalIF":2.2,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14359","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144705459","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":"Correction to “Corundum ± Magnesium-Deltalumite ± Hibonite-Bearing Objects in the CH Chondrite Sayh Al Uhaymir 290”","authors":"","doi":"10.1111/maps.14364","DOIUrl":"https://doi.org/10.1111/maps.14364","url":null,"abstract":"<p>Ryazantsev, K.M., Krot, A.N., Ma, C., Ivanova, M.A., Lorenz, C.A. and Shcherbakov, V.D. (2024), Corundum ± magnesium-deltalumite ± hibonite-bearing Objects in the CH Chondrite Sayh al Uhaymir 290. <i>Meteorit Planet Sci</i>, 59: 2608–2621. https://doi.org/10.1111/maps.14238</p><p>Figures 5 and 6 were reversed. The order of the captions was correct.</p><p>We apologize for this error.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 6","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14364","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144291789","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":"Bulk major and trace element abundances of barred olivine chondrules: Evidence about the physicochemical conditions in their region of nebular formation","authors":"M. E. Varela,&nbsp;J. Roszjar,&nbsp;P. Sylvester,&nbsp;L. Garcia","doi":"10.1111/maps.14360","DOIUrl":"https://doi.org/10.1111/maps.14360","url":null,"abstract":"<p>Barred olivine (BO) chondrules are present in ordinary and carbonaceous chondrites. We focus on the bulk major and trace element abundance composition of BO chondrules from carbonaceous, unequilibrated ordinary, and Rumuruti chondrites. Their bulk Fe/(FeO + MgO) wt% content versus the FeO wt% in olivine was used to divide these objects into FeO-poor and FeO-rich BO chondrules. The trace element content of bulk BO chondrules reveals the absence of fractionation among the abundances of elements having different geochemical behavior (e.g. Yb and [La-Ce]). This points to the predominance of a cosmochemical (e.g. gas/liquid or gas/solid condensation) instead of a geochemical process determining their elemental abundances. In addition, their bulk trace element content provides evidence for the physicochemical conditions that prevailed in the solar nebula during their formation. In general, such nebular regions are governed by local redox variations coupled with overall falling temperatures. The bulk chemical composition of the studied BO objects (e.g., Mg/Si bulk) suggests a time scale in which FeO-poor BO chondrules formed first in a chondrule-forming region rich in refractory trace elements. The progressive removal of refractory phases (e.g., hibonite, fassaite, melilite) led to a nebular reservoir depleted in the very refractory elements (e.g., Zr and Y) in which the rare earth elements (REEs) tend to reach equilibrium with the chondritic reservoir. From such a reservoir, the FeO-rich BO chondrules could have formed and were subsequently processed by metasomatic exchange reactions that equilibrated their moderately volatile V and Cr around chondritic values. The observed chemical variations are only possible if the studied BO chondrules behave as open systems exchanging elements with the cooling vapor. The inferred local redox variations coupled with overall falling temperatures could have taken place during the evolution of a single heterogeneous nebular reservoir in which Fe-poor and FeO-rich BO chondrules formed.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 6","pages":"1365-1383"},"PeriodicalIF":2.2,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144292757","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":"Petrogenesis of the Rantila meteorite fall and implications for the origin of aubrites","authors":"Yash Srivastava,&nbsp;Amit Basu Sarbadhikari,&nbsp;Varsha M. Nair,&nbsp;Avadh Kumar,&nbsp;Yogita Kadlag,&nbsp;Ramakant R. Mahajan,&nbsp;Neeraj Srivastava,&nbsp;Neha Panwar,&nbsp;Aditya Das,&nbsp;Ryoji Tanaka,&nbsp;James M. D. Day,&nbsp;Anil D. Shukla,&nbsp;Dwijesh Ray,&nbsp;Abhishek J. Verma,&nbsp;Alka Rani,&nbsp;Garima Arora,&nbsp;Dipak K. Panda,&nbsp;S. Vijayan,&nbsp;Anil Bhardwaj","doi":"10.1111/maps.14357","DOIUrl":"https://doi.org/10.1111/maps.14357","url":null,"abstract":"<p>Aubrites are rare meteorites from highly reduced differentiated parent bodies. The Rantila meteorite was recovered soon after falling on 17 August 2022 at Rantila and Ravel villages in Gujarat state, India. We report the petrography, mineralogy, chemical composition, oxygen- and chromium-isotope compositions, along with reflectance spectroscopy, all showing that Rantila is an aubrite. Coarse enstatite and diopside grains constitute the main mass of Rantila, while mm-wide fracture domains pervade the coarse enstatites. In the fractures, comminuted enstatite, diopside blebs, olivine, a plagioclase–silica assemblage, sulfides, and metals occur. Rantila consists of enstatite (&gt;85 vol%), diopside (~8 vol%), forsterite, albite, and silica along with various sulfides and Fe-Ni alloys. The concentration of rare earth elements is ~1–2 × CI, consistent with main group aubrites. Noble gas and nitrogen isotopic analyses reveal young exposure ages (13.81 ± 6.47 Ma), a heterogeneous nitrogen isotopic composition, and a major K-Ar resetting event around 3.2 ± 0.4 Ga in the parent body of Rantila. The bulk oxygen isotope values are within the range of aubrites. The chromium isotopic values of Rantila are consistent with main group aubrites. The mineral assemblages, texture, and crystallization modeling suggest that Rantila had an igneous origin. The mineral assemblages in fractures indicate the involvement of external melt possibly during an impact-fracturing event, which aligns well with the heterogeneous N isotopic composition. Additionally, Rantila shows a wider range of oxygen isotopes than other aubrites suggesting some extent of O isotopic heterogeneity, likely stemming from exogenous processes. The variation in intra-sample bulk O and N isotope values implies inherent heterogeneity within the main group aubrites, potentially caused by late-stage impact contamination.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 6","pages":"1318-1335"},"PeriodicalIF":2.2,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144292731","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":"Pairing and classification assessment of CM chondrites from the Meteorite Hills, Transantarctic Mountains","authors":"K. Righter,&nbsp;M. Welby,&nbsp;H. C. Bates,&nbsp;A. J. King,&nbsp;P. F. Schofield,&nbsp;J. Schutt,&nbsp;R. Harvey,&nbsp;J. Karner,&nbsp;B. Rougeux,&nbsp;K. Pando,&nbsp;C. Satterwhite","doi":"10.1111/maps.14353","DOIUrl":"https://doi.org/10.1111/maps.14353","url":null,"abstract":"<p>The Meteorite Hills dense collection area in the Transantarctic Mountains has yielded 1130 meteorites over several ANSMET field seasons. Twenty-three CM carbonaceous chondrites were recovered as part of the 2000–2001 and 2001–2002 field seasons. Many of these CMs have unique or rare features, but most are small (&lt;50 g), making their preservation of highest priority, so material can be available for future researchers. One major contributor to preservation is knowing which samples are paired with others. Because CM chondrites are fine grained and petrographic features are subtle, standard petrography is not as helpful in classification. To strengthen the understanding of pairing and classification, we initiated a focused study of the 23 CM chondrites recovered from Meteorite Hills. Combining magnetic susceptibility (MS), modal mineralogy as determined using X-ray diffraction (XRD), and published information about a subset of samples, we have reassessed the classification and pairing. Many samples have MS log <i>χ</i> values between 3.7 and 3.9, but there are a few exceptions such as MET 00432 (4.85), MET 01076 and 77 (4.06 and 4.63, respectively), and MET 01073 (3.21). Fifteen of the samples exhibit intermediate to high levels of aqueous alteration with phyllosilicate fractions (PSF) of 0.88–0.93. A trio of samples exhibit even higher levels of alteration with PSFs of 0.96–0.98. Find locations and cosmic ray exposure (CRE) ages of these two groups are similar and the latter very short at 0.1–0.2 Ma, raising the possibility that they are all part of the same heterogeneous fall. Since the three heavily altered samples are rare and have distinctive mineralogy relative to other MET CMs, they should be preserved regardless of whether they are from one large fall or two separate falls. Two samples (MET 01076 and MET 01077) contain a much greater fraction of olivine and pyroxene, have longer CRE ages, and most likely are heated CM chondrites. Three samples are unpaired and have unique characteristics: MET 00432 has a high magnetite fraction and other mineralogical and chemical properties comparable to C2 ungrouped chondrites such as Tagish Lake and Tarda, while MET 001087 (PSF = 0.77) and MET 00633 (PSF = 0.76) are less aqueously altered than the other meteorites, with the former in particular showing a significant tochilinite peak in its XRD pattern. Although MET 00633 could arguably be part of the larger pairing group of samples given its similar find location, we recommend keeping it unpaired given its distinct mineralogy.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 5","pages":"1249-1262"},"PeriodicalIF":2.2,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143930262","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":"Hydration and dehydration of CM chondrites revealed by X-ray diffraction combined with textural observations and compositional data","authors":"Naoya Imae,&nbsp;Makoto Kimura,&nbsp;Akira Yamaguchi","doi":"10.1111/maps.14348","DOIUrl":"https://doi.org/10.1111/maps.14348","url":null,"abstract":"<p>The in-plane rotation method is used to obtain X-ray random diffraction (XRD) patterns of polished thin sections of 10 CM chondrites. The samples include five intermediately altered CM chondrites with subtypes 2.6–2.3, two heavily altered CM chondrites with subtype 2.0 and three with secondary heating after hydration (Y 980036, Y 980051, and Jbilet Winselwan). These CM chondrites are compared to each other as well as four previously analyzed CM meteorites of subtypes 3.0–2.8 and 2.0. The same thin sections also underwent textural observations and compositional analyses. Unheated CM chondrites display systematic mineralogical changes. As the alteration degree increases from subtypes 3.0–2.0, the presence of olivine and clinoenstatite decreases, while that of serpentines increases. The abundance of tochilinite significantly increases from 2.7 to 2.3 but then decreases from 2.3 to 2.0. Subtype 2.0 consists of relatively more Mg-rich serpentine than Fe-rich serpentine (cronstedtite). The XRD identified only Mg-serpentine from Jbilet Winselwan, suggesting selective decomposition of Fe-rich serpentine (cronstedtite), while all hydrous minerals in Y 980036 and Y 980051 decomposed. Additionally, all three CM chondrites with secondary heating after hydration show stage II or category B heating by the peak metamorphic temperature of 300–750°C. Compared to previous studies using XRD, the combination of XRD with the textural and compositional analyses using the same polished thin section, avoiding the preparation for powder samples, is a straightforward approach to characterize hydrated chondritic samples. The approach is nondestructive and can be correlated with SEM/EPMA, unlike previous XRD studies that required powdered samples.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 5","pages":"1194-1215"},"PeriodicalIF":2.2,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14348","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143930505","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":"Evidence for phosphate metasomatism in an olivine-rich achondrites","authors":"Robert W. Nicklas,&nbsp;Melody Z.-A. Chen,&nbsp;Evan J. Saltman,&nbsp;Ethan F. Baxter,&nbsp;Andrew J. Lonero,&nbsp;Anthony B. Love","doi":"10.1111/maps.14356","DOIUrl":"https://doi.org/10.1111/maps.14356","url":null,"abstract":"<p>Brachinites, brachinite-like achondrites (BLA), and other similar primitive achondrites offer important constraints on differentiation processes of the earliest formed planetesimals, as they quenched amidst early differentiation processes on their parent body. Geochemical data for all major mineral phases in two previously poorly characterized meteorites, El Medano (EM) 395 and Northwest Africa (NWA) 12532, show that while EM 395 is a typical brachinite, NWA 12532 is more unusual, containing a high abundance of non-equilibrated apatite (1.26%) likely formed by a late-stage metasomatic event. These new data demonstrate that metasomatism by a P-Cl-Ca-rich fluid probably occurred on the brachinite parent body. This metasomatism may have occurred either during normal cooling of the asteroid or during later impact-related heating, consistent with the late formation of apatite in the paired andesitic achondrites Graves Nunatak (GRA) 06128 and 06129. These conclusions highlight that, while magmatism on small parent bodies ceased shortly after solar system formation, subsolidus processes may have continued much longer, and that metasomatism must be considered when interpreting bulk rock geochemical signatures of primitive achondrites.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 6","pages":"1302-1317"},"PeriodicalIF":2.2,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14356","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144292854","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 14C and 14C/10Be terrestrial age dating systems for meteorites using experimental data and model calculations","authors":"Mohammad Tauseef,&nbsp;Ingo Leya,&nbsp;Jérôme Gattacceca,&nbsp;Sönke Szidat,&nbsp;Régis Braucher,&nbsp;Pascal M. Kruttasch,&nbsp;Anna Zappatini,&nbsp;ASTER Team","doi":"10.1111/maps.14355","DOIUrl":"https://doi.org/10.1111/maps.14355","url":null,"abstract":"<p>This study presents a refined approach to determine ¹⁴C saturation activities and ¹⁴C/¹⁰Be saturation activity ratios in chondritic meteorites with the goal to improve terrestrial age dating. By combining new model calculations for ¹⁰Be, ¹⁴C, and cosmogenic (²²Ne/²¹Ne)_cos, along with experimental data from 17 freshly fallen chondrites, we established reliable correlations for ¹⁴C production rates and ¹⁴C/¹⁰Be production rate ratios as a function of (²²Ne/²¹Ne)_cos. The experimental data agree with the model calculations, and they fully confirm that ¹⁴C production rates and ¹⁴C/¹⁰Be production rate ratios depend on shielding. Constrained correlations describe the experimental data for all shielding conditions and all ordinary chondrites mostly within the uncertainties given by the model. The new correlations therefore provide a significant improvement compared to the earlier approaches, in which average meteorite-type-dependent ¹⁴C production rates and average ¹⁴C/¹⁰Be production rate ratios were assumed. Ignoring the shielding dependence introduces a size-dependent bias into the terrestrial age database. This study enables the determination of shielding-corrected ¹⁴C saturation activities and ¹⁴C/¹⁰Be production rate ratios to calculate shielding-corrected terrestrial ages for meteorites reducing or eliminating a size bias in the database. In addition, this novel approach enables to give reliable uncertainty estimates of within 15% for the ¹⁴C and ¹⁴C-¹⁰Be terrestrial ages.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 5","pages":"1263-1283"},"PeriodicalIF":2.2,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143930534","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":"Chemical, isotopic (O, He, U), and petrological characteristics of a slowly cooled enriched gabbroic shergottite, Northwest Africa 13134","authors":"Lee Saper,&nbsp;Yang Liu,&nbsp;Michael A. Kipp,&nbsp;David Burney,&nbsp;Chi Ma,&nbsp;Francois L. H. Tissot,&nbsp;Edward Young,&nbsp;Jonathan Treffkorn,&nbsp;Kenneth A. Farley","doi":"10.1111/maps.14345","DOIUrl":"https://doi.org/10.1111/maps.14345","url":null,"abstract":"<p>Northwest Africa 13134 is a coarse-grained gabbro with an oxygen isotopic composition consistent with a Martian origin and is classified as an enriched shergottite based on its bulk trace element abundances and bulk La/Yb ratio of 1.53. The meteorite is composed of a framework of large pyroxene rods up to 6 mm in longest dimension (64% by area) with interstitial maskelynite (formerly plagioclase; 28% by area). Minor phases include merrillite and apatite, Fe-Ti oxides, and Fe-sulfides; trace phases such as baddeleyite, tranquillityite, fayalitic olivine, silica, and a felspathic phase are observed in evolved mesostasis pockets and partially crystallized magmatic inclusions in minerals. Individual pyroxene rods display a distinctive patchy Ca zoning pattern of juxtaposed low-Ca (pigeonite) and high-Ca (augite) patches with a common crystallographic orientation indicating epitaxial growth. Low-Ca pigeonite is the volumetrically dominant pyroxene phase (~70% of exposed pyroxene) and was the primary liquidus phase, followed closely by augite. Plagioclase crystallized along with the other minor phases from the residual melt between cumulus pyroxene rods. Pyroxenes display ubiquitous exsolution lamellae with typical widths and spacings of 1–2 μm. Sulfide grains are characterized by flame-shaped lamellar intergrowths of hexagonal pyrrhotite (Fe_0.90S) and slightly metal-deficient pyrrhotite (Fe_0.98S), along with minor pentlandite and chalcopyrite. The pyroxene and sulfide microtextures suggest that the gabbro experienced slow and protracted subsolidus cooling. Ilmenite-oxide pairs imply an oxygen fugacity of ~1 log unit below the fayalite–magnetite–quartz buffer at a closure T ≈ 875°C. Collectively, the texture and bulk composition suggest that Northwest Africa 13134 represents a slowly cooled and coarsely crystalline portion of a solidified magma body similar to the source of the enriched basaltic shergottites. Magnetite occurs locally as veins crosscutting pyrrhotite grains and in oxide–phosphate symplectites observed at merrillite–apatite phase boundaries. The presence of magnetite in the sample suggests that at various stages of cooling, the gabbro interacted with relatively oxidized fluids, which could be of deuteric or exogeneous origin. A cosmic-ray exposure age of 2.8–4.0 Ma was calculated based on ³He measured in pyroxene grain separates and overlaps with other shergottites. Finally, we present the first bulk uranium isotope measurement of a Martian meteorite: δ²³⁸U = −0.22 ± 0.10‰ and δ²³⁴U_sec = +9.57 ± 0.35‰. These values indicate slight excesses in heavy U but overlap with the distribution of U isotope compositions of the Earth and other solar system materials.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 5","pages":"1119-1150"},"PeriodicalIF":2.2,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143930456","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":"Cover","authors":"","doi":"10.1111/maps.14201","DOIUrl":"https://doi.org/10.1111/maps.14201","url":null,"abstract":"<p>\u0000 \u0000 <figure>\u0000 <div><picture>\u0000 <source></source></picture><p></p>\u0000 </div>\u0000 </figure>\u0000 </p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 4","pages":"i"},"PeriodicalIF":2.2,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14201","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143809624","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}