Meteoritics & Planetary Science最新文献

{"title":"Revised chronology and expanded insights: Geologic perspective on the Luna impact event and its influence on the Harappan Civilization","authors":"G. K. Indu,&nbsp;S. James,&nbsp;Sachana Sathyan,&nbsp;J. Aswathi,&nbsp;V. R. Rani,&nbsp;V. M. Nair,&nbsp;Libiya M. Varghese,&nbsp;K. S. Sajinkumar,&nbsp;Nayan Sharma,&nbsp;Mitthu Dhali,&nbsp;Aryavart Anand,&nbsp;V. J. Rajesh,&nbsp;M. N. Praveen,&nbsp;Anil Chavan,&nbsp;Subhash Bhandari,&nbsp;Javed N. Malik","doi":"10.1111/maps.14308","DOIUrl":"https://doi.org/10.1111/maps.14308","url":null,"abstract":"<p>Luna is a potential impact crater located in the Banni Plains of the Kutch Basin in western India. The suspected impactites, collected from a 1-m deep trench near the vicinity of the Luna structure, possess a range of physical (porosity and magnetism) properties. Petrographic studies reveal that these impactites are dominated by wüstite, kirschsteinite, spinel, olivine, and quartz (in decreasing order of abundance), with a few silica grains exhibiting potential planar fractures (PF). These impactites can be grouped into three distinct melt classes based on their wüstite and kirschsteinite content (classified as Ca-rich, Ca-poor, and transitional type). Spectroscopic analysis indicates a higher concentration of wüstite in magnetic samples, whereas weakly magnetic to non-magnetic samples have an elevated presence of kirschsteinite. Major oxide geochemistry comparison between the impactites and the surrounding Banni Plain sediments show that some Luna impactites have a chemical affinity with a terrestrial or transitional setting, whereas the remaining samples portray a non-terrestrial trend suggesting notable mixing of target rock and projectile material. Optically stimulated luminescence dating of the sediment layer containing the impactites yielded an age of 4045 ± 182 years for the impact, consistent with the earlier proposed age of &lt;6900 years based on radiocarbon dating. The revised age places the Luna impact event much closer to the time frame of the Harappan Civilization's decline, suggesting that it may have had a greater impact on the Harappan Civilization than previously thought.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 3","pages":"422-441"},"PeriodicalIF":2.2,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143632763","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":"Petrology and shock history of hybrid lunar feldspathic–troctolitic breccia Northwest Africa 11515","authors":"Y. Li,&nbsp;P. J. A. McCausland,&nbsp;R. L. Flemming,&nbsp;G. R. Osinski","doi":"10.1111/maps.14301","DOIUrl":"https://doi.org/10.1111/maps.14301","url":null,"abstract":"<p>Lunar impact breccia meteorites contain clasts from unknown lunar regions, including areas not studied by past missions. These meteorites offer a unique opportunity to expand our knowledge of the Moon's crustal and mantle composition and processes. The recently classified lunar meteorite Northwest Africa (NWA) 11515 is a moderately shocked feldspathic breccia with anorthite plagioclase and mafic minerals. In this work, we report the shock history of lithic clasts using 2-D micro-X-ray diffraction, detailed mineralogy from micro-X-ray fluorescence, and electron probe microanalysis. NWA 11515 shows moderately shocked anorthite and highly shocked olivine and pyroxene. The plagioclase composition is invariant (An96.4 ± 0.7, <i>n</i> = 52), with variable mafic clasts overlapping Mg- and FAN-suite lithologies (Mg# 84.5 to 45.6 for olivine; Mg# 85.6 to 32.2 for pyroxene), similar to KREEP-depleted troctolites in Allan Hills A81005. Spinel-group oxides vary from aluminous spinel to chromite and ulvöspinel. We also observed slow-cooled augite Ca-poor pyroxene exsolution clasts and fast-quenched fine-grained anorthite–olivine co-crystallized clasts (&lt;5 μm), indicating different cooling histories. Combining petrological observations with published geochemical data, we show NWA 11515 has the mixed lithology of ferroan anorthosites with KREEP-poor magnesian rock fragments. With shock analysis, the materials are likely from a crater with minimum size of 7 km. Finally, we examined the published geochemical data for other lunar meteorites and hypothesize that other typical feldspathic breccias could contain magnesian clasts, suggesting the subdivision of typical feldspathic breccia into magnesian clast-hosting breccia and ferroan feldspathic breccia. This implies that non-KREEP magnesian magmatism might be more widespread in the post-LMO era on lunar highlands.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 2","pages":"347-370"},"PeriodicalIF":2.2,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143423720","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":"Search for pre-accretionary irradiation effects in calcium-aluminum inclusions from the CV3 chondrite Allende","authors":"P. Ghaznavi,&nbsp;C. Burkhardt,&nbsp;F. L. H. Tissot,&nbsp;I. Leya","doi":"10.1111/maps.14300","DOIUrl":"https://doi.org/10.1111/maps.14300","url":null,"abstract":"<p>Calcium-aluminum-rich inclusions (CAIs) are the first objects that formed in the solar accretion disk and therefore provide valuable insights into the evolution of the early solar system. A long-standing question regarding this earliest formative period relates to the storage of CAIs in the 1–4 Myr time period between their formation and later accretion into chondrite parent bodies. Were the CAIs stored in a pre-existing parent body, or in distant parts of the solar accretion disk? In the latter scenario, CAIs might have been exposed to cosmic rays, either from the galaxy or from the Sun and such pre-accretion irradiation effects might be detectable. We searched for such pre-accretional irradiation effects in 7 fine- and 11 coarse-grained CAIs from the CV 3.6 carbonaceous chondrite Allende. The extracted samples were analyzed for their major chemical composition and all samples were analyzed using μCT techniques. Using physical model calculations, ²¹Ne_cos and (²²Ne/²¹Ne)_cos production rate ratios were calculated for each CAI by fully considering their individual chemical composition. Measured He, Ne, Ar, and Kr isotope compositions of the CAIs show cosmogenic signals; clear signals for He and Ne isotopes; and detectable signals for some of the Ar and Kr isotopes. In addition, most samples show clear indications for radiogenic ⁴He and some samples show evidence for radiogenic ⁴⁰Ar. Higher ³⁶Ar/³⁸Ar, ²²Ne/²¹Ne, ⁸⁰Kr/⁸⁴Kr, and ⁸²Kr/⁸⁴Kr ratios together with lower cosmogenic ³⁸Ar_cos concentrations in fine-grained CAIs compared to coarse-grained CAIs are consistent with more alteration of the former compared to the latter. The CRE ages for the CAIs range between 4.12 ± 0.41 Myr and 6.40 ± 0.63 Myr. Statistical tests indicate that the data are normally distributed with no outliers, indicating that all CAIs share a common irradiation history, likely the irradiation in the Allende meteoroid. The average CRE age of 4.87 ± 0.19 Myr agrees with the nominally accepted CRE age of Allende of ~5.2 Myr. There is no correlation between ²¹Ne_cos concentrations and indicators of aqueous alteration like Na and/or U concentrations. The lack of correlation together with the finding of normally distributed modeled CRE ages indicates that either none of the studied CAIs experienced a pre-accretion irradiation before parent body compaction and/or that any pre-accretion irradiation effects have been completely erased during aqueous alteration events. Taking alteration aside, the findings are not in favor of X-wind type models but are more consistent with the idea of CAI outward transport in an expanding disk.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 2","pages":"247-272"},"PeriodicalIF":2.2,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14300","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143423523","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":"Geology, gravity, and numerical modeling of the Nova Colinas impact structure, Parnaíba Basin, Brazil","authors":"Pietro Demattê Avona,&nbsp;Alvaro Penteado Crósta,&nbsp;Marcos Alberto Rodrigues Vasconcelos,&nbsp;Evan Bjonnes,&nbsp;Fernando Lessa Pereira,&nbsp;Ana Maria Góes","doi":"10.1111/maps.14306","DOIUrl":"https://doi.org/10.1111/maps.14306","url":null,"abstract":"<p>Nova Colinas, centered at 07°09′33″ S/46°06′30″ W, is the ninth confirmed complex impact structure in Brazil and the fifth in the Parnaíba Basin, with a diameter of ~6.5–7 km and a nearly circular shape. Impactites include shocked siltstones from the Pedra de Fogo Fm. found at the central peak, brecciated sandstone from the Sambaíba Fm. bearing microscopic shock features, and brecciated basalt from the Mosquito Fm. bearing shatter cones. The impact event's age has been constrained to the interval from ~130 to ~199 Ma based on the local stratigraphy. Due to its moderate to advanced stage of erosion, geophysical modeling combined with geological field data were employed for its characterization. A new geological map was produced through field observations and remote sensing image interpretation, as well as a 3-D model based on ground gravity data and numerical modeling. iSALE2D shock physics code was employed to simulate the formation of Nova Colinas crater. The results revealed its main structural zones: the central uplift, annular basin, and outer rim, each associated with specific lithostratigraphic units from the Parnaíba Basin. Bouguer residual anomalies ranged from −3.6 to 1.2 mGal, with a nearly circular positive anomaly at the center of the structure, surrounded by a negative anomaly. 3-D gravity data inversion indicated a buried high-density body, likely due to the uplift of a diabase sill. Results of the numerical modeling point out that the final crater reached gravitational stability with a diameter of ~7 km and a depth of ~240 m, suggesting that a narrow outcrop strip of the Motuca Fm. was uplifted to a higher level compared to the Sambaíba Fm. strata, forming an antiform-like “arch” that creates an inner ring that exposes rocks of the Motuca Formation.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 2","pages":"286-307"},"PeriodicalIF":2.2,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143423522","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":"Petrologic characterization of CO3.0 chondrites: Implications for 60Fe-60Ni analyses","authors":"Myriam Telus,&nbsp;Tyler D. Wickland,&nbsp;Kyle Kim,&nbsp;Steven Simon","doi":"10.1111/maps.14299","DOIUrl":"https://doi.org/10.1111/maps.14299","url":null,"abstract":"<p>Samples in which Fe and Ni isotopes have not been disturbed by secondary processing are essential for constraining the initial solar system abundance of short-lived radionuclide ⁶⁰Fe, (⁶⁰Fe/⁵⁶Fe)_SS. However, Fe- and Ni-enriched veins and fractures within chondrules in unequilibrated ordinary chondrites (UOCs) imply late-stage open-system alteration that poses a potential problem for both bulk and <i>in situ</i> ⁶⁰Fe-⁶⁰Ni systematics. This study focuses on petrologic characterization of CO3.0s, which show significantly less secondary alteration than UOCs, potentially making them better targets for studying ⁶⁰Fe-⁶⁰Ni systematics. We determined the petrologic type of several CO3.0 meteorites with two independent approaches, Raman spectroscopy of matrix material and Cr₂O₃ content of FeO-rich olivine grains. CO3 chondrites analyzed in this study range from 3.00 to 3.2 in petrologic type with slight variations between results from the two different methods. Upon analyzing two thin sections of DOM 08006, one of the most pristine CO3 chondrites known, we found a chemically anomalous region, indicative of parent body hydrothermal alteration. Using the X-ray fluorescence microscopy beamline at the Australian Synchrotron, we collected high-resolution quantitative element maps to evaluate Fe and Ni mobilization for several CO3.0s. These results indicate that late-stage Fe and Ni mobilization like that observed in UOC samples is minor for most CO3 chondrites, highly localized and mostly limited to chondrule rims. Our results support that CO3.0s are well suited for further investigation of ⁶⁰Fe-⁶⁰Ni systematics and that detailed characterization of both the petrologic type and late-stage Fe and Ni mobilization of samples is important for further development of this short-lived radionuclide system.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 2","pages":"225-246"},"PeriodicalIF":2.2,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14299","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143424020","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":"New high-pressure Fe-Ti oxide minerals in the Shergotty Martian meteorite: Feiite, Fe2+2(Fe2+Ti4+)O5, liuite, FeTiO3, and tschaunerite, (Fe2+)(Fe2+Ti4+)O4","authors":"Chi Ma,&nbsp;Oliver Tschauner,&nbsp;John R. Beckett,&nbsp;Vitali B. Prakapenka","doi":"10.1111/maps.14302","DOIUrl":"https://doi.org/10.1111/maps.14302","url":null,"abstract":"<p>High-pressure oxides like perovskite-type FeTiO₃, CaTi₂O₄-type Fe₂TiO₄, and ferrous-ferric oxides that form polysomes between wüstite and CaFe₂O₄-type Fe₃O₄ are potential carriers of Fe, Ti, and other transition metals in the mantle and may play an important role in the redox budget of the deep Earth. Here, we report the occurrence of three of these phases as the new minerals: feiite (Sr₂Tl₂O₅-type Fe²⁺₂(Fe²⁺Ti⁴⁺)O₅), liuite (FeTiO₃ with a GdFeO₃-type perovskite structure), and tschaunerite (CaTi₂O₄-type (Fe²⁺)(Fe²⁺Ti⁴⁺)O₄), along with wangdaodeite (LiNbO₃-type FeTiO₃) in a transformed ulvöspinel clast entrained in a shock melt pocket in the Shergotty Martian meteorite. We show that reaction between the shocked ulvöspinel precursor and melt occurred at pressures between 20 and 25 GPa. The high-pressure Fe-, Ti-minerals lost Fe and O to the surrounding shock melt in exchange for Si, Mg, and Ca. Concentrations of Si and Mg in all of these clast phases and of Na in liuite are significant. They substantiate chemical interaction of the clast with melt during the shock event and highlight potential elemental distributions in complex Fe- and Ti-rich lithologies at pressures of the deep transition zone to shallow lower mantle.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 3","pages":"375-391"},"PeriodicalIF":2.2,"publicationDate":"2024-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143633125","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":"Methylene-to-methyl ratio variability in Ryugu samples: Clues to a heterogeneous aqueous alteration","authors":"Zélia Dionnet,&nbsp;Zahia Djouadi,&nbsp;Lukas Delaye,&nbsp;Lucas Caron,&nbsp;Rosario Brunetto,&nbsp;Alice Aléon-Toppani,&nbsp;Cateline Lantz,&nbsp;Stefano Rubino,&nbsp;Donia Baklouti,&nbsp;Tomoki Nakamura,&nbsp;Ferenc Borondics,&nbsp;Christophe Sandt,&nbsp;Megumi Matsumoto,&nbsp;Kana Amano,&nbsp;Tomoyo Morita,&nbsp;Hisayoshi Yurimoto,&nbsp;Takaaki Noguchi,&nbsp;Ryuji Okazaki,&nbsp;Hikaru Yabuta,&nbsp;Hiroshi Naraoka,&nbsp;Kanako Sakamoto,&nbsp;Shogo Tachibana,&nbsp;Toru Yada,&nbsp;Masahiro Nishimura,&nbsp;Aiko Nakato,&nbsp;Akiko Miyazaki,&nbsp;Kasumi Yogata,&nbsp;Masanao Abe,&nbsp;Tatsuaki Okada,&nbsp;Tomohiro Usui,&nbsp;Makoto Yoshikawa,&nbsp;Takanao Saiki,&nbsp;Satoshi Tanaka,&nbsp;Fuyuto Terui,&nbsp;Satoru Nakazawa,&nbsp;Seiichiro Watanabe,&nbsp;Yuichi Tsuda,&nbsp;the Hayabusa2-initial-analysis Stone team","doi":"10.1111/maps.14304","DOIUrl":"https://doi.org/10.1111/maps.14304","url":null,"abstract":"<p>Understanding the processes of aqueous alteration within primitive bodies is crucial for unraveling the complex history of early planetesimals. To better identify the signs of this process and its consequences, we have studied the heterogeneity at a micrometric scale of the structure of the aliphatic organic compounds and its relationship to its mineralogical environment. Here, we report an analysis performed on two micrometric grains of Ryugu (C0002-FC027 and C0002-FC028). The samples were crushed in a diamond compression cell and analyzed using high-spatial resolution Fourier Transform InfraRed (FT-IR) hyperspectral imaging measurements conducted in transmission mode. We showed here the spatial distributions of the main components and the structural heterogeneity of the aliphatic organic matter highlighting a micrometer-scale variability in the methylene-to-methyl ratio. Moreover, we connected this heterogeneity to the one of the phyllosilicate band positions. Our findings indicate that the organic matter within Ryugu's micrometric grains underwent varying degrees of aqueous alteration in distinct microenvironments resulting in an elongation of the length of their aliphatic chains, and/or a reduction in their branching and/or cross-linking.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 2","pages":"273-285"},"PeriodicalIF":2.2,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143424253","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":"Cafeosite, Ca4Fe2+3Fe3+2□O6S4, a new meteoritic oxysulfide, a redox indicator of metamorphic alteration of carbonaceous asteroids","authors":"Marina A. Ivanova,&nbsp;Sergey N. Britvin,&nbsp;Roza I. Gulyaeva,&nbsp;Sofia A. Petrova,&nbsp;Nina G. Zinovieva,&nbsp;Vladimir V. Kozlov,&nbsp;Stanislav N. Tyushnyakov,&nbsp;Anatoly V. Kasatkin","doi":"10.1111/maps.14296","DOIUrl":"https://doi.org/10.1111/maps.14296","url":null,"abstract":"&lt;p&gt;A natural iron-bearing oxysulfide, named сafeosite after its chemical composition, is a unique example of a mineral that simultaneously contains iron in three oxidation states: Fe&lt;sup&gt;3+&lt;/sup&gt;, Fe&lt;sup&gt;2+&lt;/sup&gt;, and intermediate between Fe&lt;sup&gt;2+&lt;/sup&gt; and Fe&lt;sup&gt;0&lt;/sup&gt; involved in metallic-type Fe&lt;span&gt;&lt;/span&gt;Fe bonding. Cafeosite was discovered in metamorphosed carbonaceous chondrite Dhofar 225, which is classified as CM-anomalous but likely related to the CY (Yamato-type) group. The mineral occurs as tiny anhedral grains that coalesce into irregular aggregates up to 20 μm, commonly encrusted by micrometer-thick troilite or pyrrhotite rims. The grains are randomly disseminated within a chondrite matrix composed of thermally altered phyllosilicates. Associated accessory minerals are troilite, pyrrhotite, Fe-rich, Al-bearing olivine, unknown Al-bearing Fe sulfide, Al-rich chromite, kamacite, awaruite, pentlandite, escolaite, and perovskite. In reflected light, cafeosite is gray, with no internal reflections. Anisotropy is moderate, bireflectance in gray hues. Infrared microspectroscopy did not reveal any bands attributable to (OH)&lt;sup&gt;−&lt;/sup&gt;, H&lt;sub&gt;2&lt;/sub&gt;O or CO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;2−&lt;/sup&gt; vibrations. Owing to the small grain size, the crystal structure of the mineral has been studied using synthetic analog, which was found to be isostructural with natural cafeosite based on electron backscatter diffraction (EBSD) data. Cafeosite is orthorhombic, space group &lt;i&gt;Cmce&lt;/i&gt; (#64), &lt;i&gt;a&lt;/i&gt; 17.4856(9), &lt;i&gt;b&lt;/i&gt; 11.1516(5), &lt;i&gt;c&lt;/i&gt; 11.1543(5) Å, &lt;i&gt;V&lt;/i&gt; 2175.0(2) Å&lt;sup&gt;3&lt;/sup&gt;, &lt;i&gt;Z&lt;/i&gt; = 8, &lt;i&gt;D&lt;/i&gt;&lt;sub&gt;x&lt;/sub&gt; = 4.11 g cm&lt;sup&gt;−3&lt;/sup&gt;. The crystal structure has been solved and refined to &lt;i&gt;R&lt;/i&gt;&lt;sub&gt;1&lt;/sub&gt; = 0.039 for 1105 unique reflections. Chemical composition of both natural and synthetic cafeosite corresponds to the formula Ca&lt;sub&gt;4&lt;/sub&gt;Fe&lt;sup&gt;2+&lt;/sup&gt;&lt;sub&gt;3&lt;/sub&gt;Fe&lt;sup&gt;3+&lt;/sup&gt;&lt;sub&gt;2&lt;/sub&gt;(□&lt;sub&gt;1−x&lt;/sub&gt;Fe&lt;sub&gt;x&lt;/sub&gt;)O&lt;sub&gt;6&lt;/sub&gt;S&lt;sub&gt;4&lt;/sub&gt; where (□&lt;sub&gt;1−&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;Fe&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;) denotes structural vacancy partially occupied by semimetallic-type Fe (&lt;i&gt;x&lt;/i&gt; = 0.2–0.3). The ideal endmember formula of the mineral is Ca&lt;sub&gt;4&lt;/sub&gt;Fe&lt;sup&gt;2+&lt;/sup&gt;&lt;sub&gt;3&lt;/sub&gt;Fe&lt;sup&gt;3+&lt;/sup&gt;&lt;sub&gt;2&lt;/sub&gt;□O&lt;sub&gt;6&lt;/sub&gt;S&lt;sub&gt;4&lt;/sub&gt;. Cafeosite was likely formed from previously altered precursor material of Dhofar 225, which, like common CM chondrites, consisted of phyllosilicates, Ca-bearing carbonates, tochilinite-like sulfides–hydroxides and pyrrhotite. During thermal metamorphism at temperatures between 750 and 900°C, sulfides–hydroxides were partly sintered with calcined carbonates and iron oxides, resulting in cafeosite formation. Due to varying and redox-dependent contents of Fe&lt;sup&gt;3+&lt;/sup&gt; and Fe&lt;sup&gt;2+&lt;/sup&gt;, as well as the presence of metallic-type Fe in the structure, cafeosite could be regarded as a single-phase redox indicator alternative to the known triple-phase buffers, for example, iron–magnetite–pyrrhotite (IM-Po), iron–wüsti","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 2","pages":"175-189"},"PeriodicalIF":2.2,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143424254","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":"2021 Service Award for Christian Koeberl","authors":"Janice L. Bishop,&nbsp;Peter A. J. Englert","doi":"10.1111/maps.14294","DOIUrl":"https://doi.org/10.1111/maps.14294","url":null,"abstract":"","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 2","pages":"E1-E3"},"PeriodicalIF":2.2,"publicationDate":"2024-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143424198","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":"Petrofabrics in the CM chondrite Kolang: Evidence for non-spherical chondrules in the protoplanetary disk","authors":"Laura E. Jenkins,&nbsp;Martin R. Lee,&nbsp;Luke Daly,&nbsp;Ashley J. King,&nbsp;Cameron J. Floyd,&nbsp;Peter Chung,&nbsp;Sammy Griffin","doi":"10.1111/maps.14297","DOIUrl":"https://doi.org/10.1111/maps.14297","url":null,"abstract":"<p>The alignment of non-spherical “flattened” chondrules into a petrofabric is a common feature of hydrated carbonaceous chondrite meteorites. This texture can form as a result of impacts at peak shock pressures exceeding 10 GPa. However, many carbonaceous chondrites with petrofabrics are unshocked. While several processes have been proposed to explain this incongruency, including erasure of shock effects by alteration (both aqueous and thermal), none have yet been confirmed. Kolang is a brecciated Mighei-like carbonaceous chondrite wherein analysis of chondrule shape and orientation shows that it has a pronounced petrofabric defined by elongate chondrules that is shared between clasts with differing aqueous and thermal alteration histories. Its petrofabric, therefore, must have developed after the altered clasts had been juxtaposed; any sign of shock associated with impact-driven deformation cannot have been erased. We have investigated the shock experienced by Kolang with a combination of traditional optical methods and electron backscatter diffraction. We find that the peak shock pressure experienced by Kolang was likely ~4–5 GPa, too low to generate an impact-induced petrofabric. Kolang has not experienced sufficient shock, whether by a single or multiple impacts, to deform its chondrules from spheres into elongate chondrules. The most likely explanation, therefore, is that Kolang accreted elongate chondrules that were aligned under relatively low pressure.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 2","pages":"190-205"},"PeriodicalIF":2.2,"publicationDate":"2024-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14297","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143424223","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}