Meteoritics & Planetary Science最新文献

{"title":"Igneous intrusion origin for the petrofabric of Erg Chech 002","authors":"C. Beros,&nbsp;K. T. Tait,&nbsp;V. E. Di Cecco,&nbsp;D. E. Moser","doi":"10.1111/maps.14182","DOIUrl":"10.1111/maps.14182","url":null,"abstract":"<p>Achondrites provide an opportunity to examine the igneous processes of differentiated bodies in our solar system. The recent discovery of several silica-rich achondrites suggests that andesitic crusts were more common among planetesimals than previously thought, though the processes behind their emplacement are not well understood. Here, electron backscatter diffraction (EBSD) is used to investigate the igneous emplacement conditions of Erg Chech 002 (EC 002), a recently discovered ungrouped achondrite representing andesitic magmatism ~2 Myr after the formation of calcium–aluminum-rich inclusions (CAIs). EBSD analyses of crystallographic preferred orientations (CPOs) for augite and plagioclase feldspar phenocrysts indicate that EC 002 exhibits a weak foliation CPO. Augite misorientation inverse pole figures (mIPF) indicate preferential slip along the (100)[001] system with a distinct shift toward the {0kl}[u0w] system in plastically deformed grains. Our findings support the hypothesis that EC 002 was likely emplaced in the lower regions of a magmatic intrusion. Augite slip signatures suggest that EC 002 crystallization and emplacement were restricted to high temperatures (&gt;800°C) and experienced at least two strain regimes. The distinct shift from a dominant (100)[001] slip system, which corresponds to high temperatures (800–1050°C), to a [0kl][u0w] slip system indicates an increased strain rate due to shock deformation (1–5 GPa) attributed to ejection by hypervelocity impact.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 7","pages":"1742-1750"},"PeriodicalIF":2.2,"publicationDate":"2024-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14182","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141123654","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":"Incipient space weathering on asteroid 162173 Ryugu recorded by pyrrhotite","authors":"Dennis Harries,&nbsp;Toru Matsumoto,&nbsp;Falko Langenhorst,&nbsp;Takaaki Noguchi,&nbsp;Akira Miyake,&nbsp;Yohei Igami,&nbsp;Mitsutaka Haruta,&nbsp;Yusuke Seto,&nbsp;Masaaki Miyahara,&nbsp;Naotaka Tomioka,&nbsp;Hikaru Saito,&nbsp;Satoshi Hata,&nbsp;Aki Takigawa,&nbsp;Yusuke Nakauchi,&nbsp;Shogo Tachibana,&nbsp;Tomoki Nakamura,&nbsp;Megumi Matsumoto,&nbsp;Hope A. Ishii,&nbsp;John P. Bradley,&nbsp;Kenta Ohtaki,&nbsp;Elena Dobrică,&nbsp;Hugues Leroux,&nbsp;Corentin Le Guillou,&nbsp;Damien Jacob,&nbsp;Francisco de la Peña,&nbsp;Sylvain Laforet,&nbsp;Bahae-eddine Mouloud,&nbsp;Maya Marinova,&nbsp;Pierre Beck,&nbsp;Van T. H. Phan,&nbsp;Rolando Rebois,&nbsp;Neyda M. Abreu,&nbsp;Jennifer Gray,&nbsp;Thomas Zega,&nbsp;Pierre-M. Zanetta,&nbsp;Michelle S. Thompson,&nbsp;Rhonda Stroud,&nbsp;Kate Burgess,&nbsp;Brittany A. Cymes,&nbsp;John C. Bridges,&nbsp;Leon Hicks,&nbsp;Martin R. Lee,&nbsp;Luke Daly,&nbsp;Phil A. Bland,&nbsp;Michael E. Zolensky,&nbsp;David R. Frank,&nbsp;James Martinez,&nbsp;Akira Tsuchiyama,&nbsp;Masahiro Yasutake,&nbsp;Junya Matsuno,&nbsp;Shota Okumura,&nbsp;Itaru Mitsukawa,&nbsp;Kentaro Uesugi,&nbsp;Masayuki Uesugi,&nbsp;Akihisa Takeuchi,&nbsp;Mingqi Sun,&nbsp;Satomi Enju,&nbsp;Tatsuhiro Michikami,&nbsp;Hisayoshi Yurimoto,&nbsp;Ryuji Okazaki,&nbsp;Hikaru Yabuta,&nbsp;Hiroshi Naraoka,&nbsp;Kanako Sakamoto,&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;Sei-ichiro Watanabe,&nbsp;Yuichi Tsuda","doi":"10.1111/maps.14176","DOIUrl":"10.1111/maps.14176","url":null,"abstract":"<p>Regolith samples returned from asteroid 162173 Ryugu by the Hayabusa2 mission provide direct means to study how space weathering operates on the surfaces of hydrous asteroids. The mechanisms of space weathering, its effects on mineral surfaces, and the characteristic time scales on which alteration occurs are central to understanding the spectroscopic properties and the taxonomy of asteroids in the solar system. Here, we investigate the behavior of the iron monosulfides mineral pyrrhotite (Fe_1−<i>x</i>S) at the earliest stages of space weathering. Using electron microscopy methods, we identified a partially exposed pyrrhotite crystal that morphologically shows evidence for mass loss due to exposure to solar wind ion irradiation. We find that crystallographic changes to the pyrrhotite can be related to sulfur loss from its space-exposed surface and the diffusive redistribution of resulting excess iron into the interior of the crystal. Diffusion profiles allow us to estimate an order of magnitude of the exposure time of a few thousand years consistent with previous estimates of space exposure. During this interval, the adjacent phyllosilicates did not acquire discernable damage, suggesting that they are less susceptible to alteration by ion irradiation than pyrrhotite.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 8","pages":"2134-2148"},"PeriodicalIF":2.2,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14176","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141128001","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":"Distribution analysis of rare earth elements in fine-grained CAIs of the Allende meteorite using multiple-spot femtosecond LA-ICP-MS","authors":"Yuki Masuda,&nbsp;Sota Niki,&nbsp;Takafumi Hirata,&nbsp;Tetsuya Yokoyama","doi":"10.1111/maps.14190","DOIUrl":"10.1111/maps.14190","url":null,"abstract":"<div>\u0000 \u0000 <p>Calcium–aluminum-rich inclusions (CAIs) in chondrites are one of the oldest materials in the solar system. Presence of refractory minerals in CAIs suggests that they formed thorough a condensation process from nebular gas of solar composition. In particular, fine-grained CAIs (FGs) have escaped melting after condensation, and thus, the elemental distribution of rare earth elements (REEs) in FG minerals provides key information for elucidating the condensation processes. Although the REE abundances of FG fragments have been investigated in previous studies, the distribution of REEs in individual FG constituent minerals remains poorly explored. Here, we demonstrate the utility of laser imaging of REE distribution in CAIs by analyzing five FGs found in the Allende CV3 chondrite using multiple-spot femtosecond laser ablation (msfsLA)-ICP-MS. The msfsLA-ICP-MS imaging system allows for a rapid acquisition of a wider range of REE distributions than previously achieved by Secondary ion mass spectrometry-based imaging techniques. Out of the five FGs examined in this study, three showed the homogeneous REE patterns, while the other two indicated variable REE patterns within each FG. These observations presumably reflect differences in the chemical processes experienced by the FGs, and indicate that multi-step chemical processes were recorded in some of the FGs. The msfsLA-ICP-MS imaging technique can characterize the elemental distribution of individual FGs under the comparable spatial resolution with high-analysis throughput, and thus, it is an effective new method for advancing the taxonomy of FGs, which will improve our understanding of the physicochemical conditions that prevailed in the early solar system.</p>\u0000 </div>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 9","pages":"2260-2275"},"PeriodicalIF":2.2,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140975864","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":"The Ordovician meteorite event in North America: Age of the Slate Islands impact structure, northern Lake Superior, Ontario, Canada","authors":"Andrew F. Parisi,&nbsp;Elizabeth J. Catlos,&nbsp;Michael E. Brookfield,&nbsp;Axel K. Schmitt,&nbsp;Daniel F. Stöckli,&nbsp;Daniel P. Miggins,&nbsp;Daniel S. Campos","doi":"10.1111/maps.14183","DOIUrl":"10.1111/maps.14183","url":null,"abstract":"<p>The Slate Islands (Ontario) is one of Canada's larger impact structures at 32 km in diameter and has been linked to the Ordovician meteorite event (OME). We report zircon U–Pb dates from two suevite and two syenite samples collected from the Slate Islands. Plagioclase ⁴⁰Ar/³⁹Ar dates were also obtained from one of the samples. The plagioclase and most zircon dates record pre-impact ages with links to known tectonic events, including those associated with the assembly of the Superior Craton at approximately 2700 Ma. However, Neoarchean zircon grains appear to be reset at 456.1 ± 6.9 Ma (±2<i>σ</i>) based on the lower intercept of discordia for all dated samples. The date overlaps its previously accepted age of 450 Ma and would be 2–19 million years following the parent asteroid breakup if related to the OME.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 7","pages":"1751-1774"},"PeriodicalIF":2.2,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140977838","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":"2020 Barringer Medal for Joanna Morgan","authors":"Natalia Artemieva,&nbsp;Sean Gulick","doi":"10.1111/maps.14185","DOIUrl":"10.1111/maps.14185","url":null,"abstract":"","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 S1","pages":"A477-A478"},"PeriodicalIF":2.2,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140985619","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":"Elemental and oxygen isotopic fractionation recorded in highly vaporized cosmic spherules from Widerøefjellet, Sør Rondane Mountains (East Antarctica)","authors":"Tom Boonants,&nbsp;Steven Goderis,&nbsp;Bastien Soens,&nbsp;Flore Van Maldeghem,&nbsp;Stepan M. Chernonozhkin,&nbsp;Frank Vanhaecke,&nbsp;Matthias van Ginneken,&nbsp;Christophe Snoeck,&nbsp;Philippe Claeys","doi":"10.1111/maps.14188","DOIUrl":"10.1111/maps.14188","url":null,"abstract":"<p>Upon passage through Earth's atmosphere, micrometeorites undergo variable degrees of melting and evaporation. Among the various textural and chemical groups recognized among cosmic spherules, that is, melted micrometeorites, a subset of particles may indicate anomalously high degrees of vaporization based on their chemical and isotopic properties. Here, a selection of such refractory element-enriched cosmic spherules from Widerøefjellet (Sør Rondane Mountains, East Antarctica) is characterized for their petrographic features, major and trace element concentrations (<i>N</i> = 35), and oxygen isotopic compositions (<i>N</i> = 23). Following chemical classification, the highly vaporized particles can be assigned to either the “CAT-like” or the “High Ca-Al” cosmic spherule groups. However, through the combination of major and trace element concentrations and oxygen isotopic data, a larger diversity of processes and precursor materials are identified that lead to the final compositions of refractory element-enriched particles. These include fragmentation, disproportional sampling of specific mineral constituents, differential melting, metal bead extraction, redox shifts, and evaporation. Based on specific element concentrations (e.g., Sc, Zr, Eu, Tm) and ratios (e.g., Fe/Mg, CaO + Al₂O₃/Sc + Y + Zr + Hf), and variations of O isotope compositions, “CAT-like” and “High Ca-Al” cosmic spherules likely represent a continuum between mineral endmembers from both primitive and differentiated parent bodies that experienced variable degrees of evaporation.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 9","pages":"2213-2240"},"PeriodicalIF":2.2,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140985686","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":"Non-destructive quantitative analysis of melt inclusions in extraterrestrial samples: Case study of chassignite via nanoscale X-ray computed tomography","authors":"Peiyu Wu,&nbsp;Kyle Dayton,&nbsp;Esteban Gazel,&nbsp;Teresa Porri","doi":"10.1111/maps.14180","DOIUrl":"10.1111/maps.14180","url":null,"abstract":"<p>Estimation of the composition of planetary rocks and minerals is crucial for understanding their formation processes. In this study, we present the application of X-ray nano-computed tomography (nano-XCT) for non-destructive three-dimensional (3-D) phase analysis and estimation of phase abundances in rare Martian meteorite samples, specifically chassignite Northwest Africa (NWA) 2737. We determined the most suitable laser power for minimizing artifacts and maximizing phase contrast. By utilizing nano-XCT, we successfully identified and segmented primary phases in the bulk meteorite sample. Additionally, we were able to locate and segment crystallized silicate melt inclusions within the meteorite. The phase abundances in bulk NWA 2737 and within melt inclusions calculated using nano-XCT were in good agreement with previous studies that used thin section calculations, demonstrating the reliability of nano-XCT as a non-destructive alternative for estimating bulk phase abundances in rare samples. This study develops a benchmarking protocol and demonstrates the efficacy of nano-XCT as a non-destructive technique for generating an overview of phase distribution and assemblages of melt inclusions within rare samples. Future research can benefit from combining non-destructive 3-D phase assemblage estimations with non-destructive 3-D chemical analysis techniques to achieve a fully non-destructive parental magma composition estimation of rare cumulate samples.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 7","pages":"1723-1741"},"PeriodicalIF":2.2,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140982996","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":"Origin of fabrics and olivine chemical variations preserved in brachinite and brachinite-like achondrite meteorites","authors":"Benjamin H. Gruber,&nbsp;Robert W. Nicklas,&nbsp;James M. D. Day,&nbsp;Emily J. Chin,&nbsp;Minghua Ren,&nbsp;Rachel E. Bernard","doi":"10.1111/maps.14179","DOIUrl":"10.1111/maps.14179","url":null,"abstract":"<p>Brachinites and brachinite-like achondrites are olivine-rich meteorites that represent materials after partial metal–silicate differentiation on multiple early Solar System bodies. Both meteorite types show macroscopic textures of olivine crystals, which make up &gt;70 modal percent of their mineralogy. We investigated the orientations of olivine using electron backscatter diffraction (EBSD) and elemental compositions from paired brachinite-like achondrites and one brachinite. The olivine orientations are characterized by a strong concentration of [010] axes with maxima perpendicular to the foliation/layering and a concentration of [001] axes distributed in a girdle or, in a few samples, as point maxima. Trace element abundances of the olivine in these meteorites determined using laser ablation inductively coupled plasma–mass spectrometry have uniformly low concentrations of sodium (&lt;300 μg g⁻¹), aluminum (&lt;70 μg g⁻¹), and titanium (&lt;40 μg g⁻¹) that are distinct from olivine in chondrites or within terrestrial lavas. Instead, brachinite and brachinite-like olivine compositions broadly overlap those of olivine from melt-depleted mantle lithologies on Earth. Evidence from olivine trace element geochemistry, in conjunction with mineral fabrics, supports that these meteorites formed as melt residues on their host planetary body(ies).</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 9","pages":"2191-2212"},"PeriodicalIF":2.2,"publicationDate":"2024-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14179","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140986713","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":"Formation of nanophase metallic iron through charge disproportionation of ferrous iron during micrometeoroid impact-induced splash melting","authors":"Haiyang Xian,&nbsp;Jianxi Zhu,&nbsp;Yiping Yang,&nbsp;Shan Li,&nbsp;Jiaxin Xi,&nbsp;Xiaoju Lin,&nbsp;Jieqi Xing,&nbsp;Xiao Wu,&nbsp;Hongmei Yang,&nbsp;Hongping He,&nbsp;Yi-Gang Xu","doi":"10.1111/maps.14174","DOIUrl":"10.1111/maps.14174","url":null,"abstract":"<p>Charge disproportionation of ferrous iron has been considered as one of the mechanisms for the formation of metallic iron on the lunar surface. However, the detailed mechanism of the disproportionation reaction on the Moon is yet to be elucidated. We provide direct evidence for the ferrous disproportionation reaction that produces nano phase metallic iron (npFe⁰) during a rapid cooling process after splash melting from a lunar sample returned by China's Chang'e-5 mission. Space weathering processes have resulted in the formation of three distinct zones at the rim of a pyroxene fragment, as observed through transmission electron microscopy. These zones, made up of splashed melts, newly formed melts from the substrate, and the mineral, are distinguished as I, II, and III. Quantitative analyses of the iron valence state by electron energy loss spectroscopy show that disproportionation reactions occurred in zone II at a low temperature of &lt;570°C during a rapid cooling process. The reaction led to the production of α-structure npFe⁰ and Fe³⁺ reserve in the glass phase. The npFe⁰ produced by the disproportionation reaction has a larger grain size than those formed from solar wind irradiation, implying that micrometeoroid impacts mainly contribute to the darkening of visible and near-infrared reflectance. These findings reveal a novel rim structure by repeated space weathering and a universal formation mechanism of npFe⁰ during micrometeoroid impacts, suggesting that the disproportionation reaction could be widespread on airless bodies with impact-induced splash processes.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 7","pages":"1692-1704"},"PeriodicalIF":2.2,"publicationDate":"2024-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140989196","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":"A comprehensive study of apatite grains in Ryugu rock fragments","authors":"B. J. Tkalcec,&nbsp;P. Tack,&nbsp;E. De Pauw,&nbsp;B. Bazi,&nbsp;B. Vekemans,&nbsp;M. Lindner,&nbsp;L. Vincze,&nbsp;M. Di Michiel,&nbsp;J. Garrevoet,&nbsp;G. Falkenberg,&nbsp;T. Nakamura,&nbsp;T. Morita,&nbsp;K. Amano,&nbsp;D. Nakashima,&nbsp;F. Langenhorst,&nbsp;K. Pollok,&nbsp;H. Yurimoto,&nbsp;T. Noguchi,&nbsp;R. Okazaki,&nbsp;H. Yabuta,&nbsp;H. Naraoka,&nbsp;K. Sakamoto,&nbsp;S. Tachibana,&nbsp;T. Yada,&nbsp;M. Nishimura,&nbsp;A. Nakato,&nbsp;A. Miyazaki,&nbsp;K. Yogata,&nbsp;M. Abe,&nbsp;T. Okada,&nbsp;T. Usui,&nbsp;M. Yoshikawa,&nbsp;T. Saiki,&nbsp;S. Tanaka,&nbsp;F. Terui,&nbsp;S. Nakazawa,&nbsp;S. Watanabe,&nbsp;Y. Tsuda,&nbsp;F. E. Brenker","doi":"10.1111/maps.14177","DOIUrl":"10.1111/maps.14177","url":null,"abstract":"<p>Apatite is present as an accessory phase in many meteorites and is often formed as a secondary product of aqueous alteration. Its propensity to incorporate rare earth elements (REE) results in apatite usually being the main REE-bearing phase in hydrously altered meteorites. Asteroid Ryugu is thought to have experienced pervasive aqueous alteration and material collected from the surface of Ryugu is expected to provide insight into asteroidal aqueous alteration processes without influence by terrestrial weathering. Morphologies and mineral associations of apatite grains from five rock fragments collected from the asteroid Ryugu by the Hayabusa2 spacecraft were examined and their REE concentrations were measured by synchrotron X-ray fluorescence (SXRF) spectroscopy. The main minerals associated with apatite are dolomite, magnetite, and pyrrhotite. Grain boundary corrosion of the interfaces between apatite assemblages and the surrounding matrix suggest that paragenetic formation on the asteroid was followed by a later episode of hydrous alteration. Light REE (LREE) concentration levels recorded at 20–150 times those of bulk CI levels together with a steady increase from LREE toward enrichment of medium REE (MREE, up to Er) at 50–400 times bulk CI levels may suggest postgenetic removal of LREE from Ryugu apatite grains by late-stage circulation of a hydrothermal fluid.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 8","pages":"2149-2165"},"PeriodicalIF":2.2,"publicationDate":"2024-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14177","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140989492","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}