Meteoritics & Planetary Science最新文献

{"title":"86th Annual Meeting of the Meteoritical Society (2024)","authors":"","doi":"10.1111/maps.14252","DOIUrl":"https://doi.org/10.1111/maps.14252","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":"59 S1","pages":"1"},"PeriodicalIF":2.2,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14252","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142077862","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":"Cover","authors":"","doi":"10.1111/maps.14016","DOIUrl":"https://doi.org/10.1111/maps.14016","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":"59 8","pages":"i"},"PeriodicalIF":2.2,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14016","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141991694","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":"Chondrule sizes within the CM carbonaceous chondrites and measurement methodologies","authors":"C. J. Floyd,&nbsp;S. Benito,&nbsp;P.-E. Martin,&nbsp;L. E. Jenkins,&nbsp;E. Dunham,&nbsp;L. Daly,&nbsp;M. R. Lee","doi":"10.1111/maps.14250","DOIUrl":"10.1111/maps.14250","url":null,"abstract":"<p>The sizes of chondrules are a valuable tool for understanding relationships between meteorite groups and the affinity of ungrouped chondrites, documenting temporal/spatial variability in the solar nebula, and exploring the effects of parent body processing. Many of the recently reported sizes of chondrules within the CM carbonaceous chondrites differ significantly from the established literature average and are more closely comparable to those of chondrules within CO chondrites. Here, we report an updated analysis of chondrule dimensions within the CM group based on data from 1937 chondrules, obtained across a suite of CM lithologies ranging from petrologic subtypes CM2.2 to CM2.7. Our revised average CM chondrule size is 194 μm. Among the samples examined, a relationship was observed between petrologic subtype and chondrule size such that chondrule long-axis lengths are greater in the more highly aqueously altered lithologies. These findings suggest a greater similarity between the CM and CO chondrites than previously thought and support arguments for a genetic link between the two groups (i.e., the CM-CO clan). Using the 2-D and 3-D data gathered, we also apply numerous stereological corrections to examine their usefulness in correcting 2-D chondrule measurements within the CM chondrites. Alongside this analysis, we present the details of a standardized methodology for 2-D chondrule size measurement to facilitate more reliable inter-study comparisons.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 10","pages":"2769-2788"},"PeriodicalIF":2.2,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14250","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141927342","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":"Petrographic and geochemical analysis of lunar meteorite NWA 11788: Parallels with Luna 20 and the Apollo magnesian granulites","authors":"Craig R. Hulsey,&nbsp;Katie M. O'Sullivan","doi":"10.1111/maps.14248","DOIUrl":"https://doi.org/10.1111/maps.14248","url":null,"abstract":"<p>The first in-depth geochemical and petrological analyses of new lunar meteorite Northwest Africa (NWA) 11788 were conducted with the aim of better understanding the diversity of lunar rock types. Petrography, microcomputed tomography, electron probe microanalysis, and laser ablation inductively coupled plasma mass spectrometry were employed to analyze mineralogic/elemental makeup, petrologic profile, melt history, and inferred composition of the lunar mantle from which the crystals in this sample originated from. Geochemical maps of the lunar surface were generated to constrain potential lunar launch locations for NWA 11788. Potential launch locations are concentrated in the outer rims of impact basins on the lunar Eastern nearside limb (e.g., Crisium, Fecunditatis, Marginis, Smythii) and around the South Pole–Aitken Basin. Similarities in the major, minor, and trace element chemistry of NWA 11788 along with its potential launch locations suggest a petrogenetic relationship with regolith samples returned from the Luna 20 mission and the Apollo 16 and 17 magnesian granulites. Additionally, the results of this study add to the growing body of evidence that KREEP (potassium, rare earth elements, phosphorous)-poor, Mg-suite-“like” lithologies are common in non-Apollo-type locales, that KREEP may not be required to generate lithologies like the Mg-suite, and that KREEP is not globally distributed at present.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 10","pages":"2744-2768"},"PeriodicalIF":2.2,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14248","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142429302","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":"Cosmic pears from the Havelland (Germany): Ribbeck, the twelfth recorded aubrite fall in history","authors":"Addi Bischoff,&nbsp;Markus Patzek,&nbsp;Jean-Alix Barrat,&nbsp;Jasper Berndt,&nbsp;Henner Busemann,&nbsp;Detlev Degering,&nbsp;Tommaso Di Rocco,&nbsp;Mattias Ek,&nbsp;Dennis Harries,&nbsp;Jose R. A. Godinho,&nbsp;Dieter Heinlein,&nbsp;Armin Kriele,&nbsp;Daniela Krietsch,&nbsp;Colin Maden,&nbsp;Oscar Marchhart,&nbsp;Rachael M. Marshal,&nbsp;Martin Martschini,&nbsp;Silke Merchel,&nbsp;Andreas Möller,&nbsp;Andreas Pack,&nbsp;Herbert Raab,&nbsp;Maximilian P. Reitze,&nbsp;Ina Rendtel,&nbsp;Miriam Rüfenacht,&nbsp;Oliver Sachs,&nbsp;Maria Schönbächler,&nbsp;Anja Schuppisser,&nbsp;Iris Weber,&nbsp;Alexander Wieser,&nbsp;Karl Wimmer","doi":"10.1111/maps.14245","DOIUrl":"https://doi.org/10.1111/maps.14245","url":null,"abstract":"<p>In 1889 the German poet and novelist Theodor Fontane wrote the popular literary ballad “Herr von Ribbeck auf Ribbeck im Havelland.” The Squire von Ribbeck is described as a gentle and generous person, who often gives away pears from his pear trees to children passing by and continued donating pears after his death. Now, 135 years later the rock called <i>Ribbeck</i> is giving us insight into processes that happened 4.5 billion years ago. The meteorite Ribbeck (official find location: 52°37′15″N, 12°45′40″E) fell January 21, 2024, and has been classified as a brecciated aubrite. This meteoroid actually entered the Earth's atmosphere at 00:32:38 UTC over Brandenburg, west of Berlin, and the corresponding fireball was recorded by professional all sky and video cameras. More than 200 pieces (two proved by radionuclide analysis to belong to this fresh fall) were recovered totaling about 1.8 kg. Long-lived radionuclide and noble gas data are consistent with long cosmic ray exposure (55–62 Ma) and a preatmospheric radius of Ribbeck between 20 and 30 cm. The heavily brecciated aubrite consists of major (76 ± 3 vol%) coarse-grained FeO-free enstatite (En_99.1Fs_&lt;0.04Wo_0.9), with a significant abundance (15.0 ± 2.5 vol%) of albitic plagioclase (Ab_95.3 An_2.0Or_2.7), minor forsterite (5.5 ± 1.5 vol%; Fo_99.9) and 3.5 ± 1.0 vol% of opaque phases (mainly sulfides and metals) with traces of nearly FeO-free diopside (En_53.2Wo_46.8) and K-feldspar (Ab_4.6Or_95.4). The rock has a shock degree of S3 (U-S3), and terrestrial weathering has affected metals and sulfides, resulting in the brownish appearance of rock pieces and the partial destruction of certain sulfides already within days after the fall. The bulk chemical data confirm the feldspar-bearing aubritic composition. Ribbeck is closely related to the aubrite Bishopville. Ribbeck does not contain solar wind implanted gases and is a fragmental breccia. Concerning the Ti- and O-isotope compositions, the data are similar to those of other aubrites. They are also similar to E chondrites and fall close to the data point for the bulk silicate Earth (BSE). Before the Ribbeck meteoroid entered Earth's atmosphere, it was observed in space as asteroid 2024 BX1. The aphelion distance of 2024 BX1's orbit lies in the innermost region of the asteroid belt, which is populated by the Hungaria family of minor planets characterized by their E/X-type taxonomy and considered as the likely source of aubrites. The spectral comparison of an average large-scale emission spectrum of Mercury converted into reflectance and of the Ribbeck meteorite spectrum does not show any meaningful similarities.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 10","pages":"2660-2694"},"PeriodicalIF":2.2,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14245","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142430403","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":"Characterization of bulk interior and fusion crust of Calama 009 L6 ordinary chondrite","authors":"E. V. Petrova,&nbsp;A. V. Chukin,&nbsp;G. Varga,&nbsp;Z. Dankházi,&nbsp;G. Leitus,&nbsp;I. Felner,&nbsp;E. Kuzmann,&nbsp;Z. Homonnay,&nbsp;V. I. Grokhovsky,&nbsp;M. I. Oshtrakh","doi":"10.1111/maps.14249","DOIUrl":"https://doi.org/10.1111/maps.14249","url":null,"abstract":"<p>Fragment of Calama 009 L6 ordinary chondrite recovered in the Atacama Desert was chosen for a complex study of the bulk interior and the fusion crust by scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), magnetization measurements, and Mössbauer spectroscopy. SEM demonstrated the presence of Fe-Ni-Co grains, troilite and chromite inclusions in both the bulk interior and the fusion crust as well as many veins with ferric compound. EDS showed variations in the Ni concentration within the metal grains and within one metal phase in the grain. XRD revealed some differences in the contents of various phases in the bulk interior and in the fusion crust. XRD indicated the presence of magnesioferrite in the fusion crust as well as the formation of goethite nanoparticles with the mean size of 9 nm in both the bulk interior and the fusion crust. Magnetization measurements demonstrated the ferrimagnetic–paramagnetic phase transition in chromite at 44 K and low values of the saturation magnetization moments (6.46 and 3.26 emu g⁻¹ at 100 K) for the bulk interior and the fusion crust, respectively, due to the lack of Fe-Ni-Co alloy as a result of weathering. The Mössbauer spectra of the bulk interior and the fusion crust showed some differences in the number and relative areas of spectral components. The revealing of the Mössbauer spectral components related to ⁵⁷Fe in the M1 and M2 sites in olivine and orthopyroxene as well as determining the Fe²⁺ occupations of these sites from XRD permitted us to estimate the temperature of equilibrium cation distribution for these silicates which are (i) 662 K (XRD) and 706 K (Mössbauer spectroscopy) for olivine and (ii) 893 K (XRD) and 910 K (Mössbauer spectroscopy) for orthopyroxene.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 10","pages":"2865-2879"},"PeriodicalIF":2.2,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142430308","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":"Zircon U-Pb provenance analysis of impact melt and target rocks from the Rochechouart impact structure, France","authors":"Daniela Guerrero,&nbsp;Wolf Uwe Reimold,&nbsp;Natalia Hauser,&nbsp;Igor Figueiredo,&nbsp;Lucas Kenni,&nbsp;Philippe Lambert","doi":"10.1111/maps.14247","DOIUrl":"https://doi.org/10.1111/maps.14247","url":null,"abstract":"<p>The Rochechouart impact structure in the northwestern part of the French Massif Central (FMC) has a great diversity of impactites, including monomict impact breccias, suevite, and impact melt rocks (IMRs). The structure is strongly eroded, which allows the study of impactites of the crater fill and the transition into the crater floor. The FMC has had a multistage geological evolution from the late Neoproterozoic to the Ordovician (600–450 Ma) until the later stages of the Variscan orogeny (~300 Ma). Previous geochronological work on Rochechouart has been focused mainly on the impactites and constraining the impact age, and scarce work has been done on the FMC-related target rocks. Here, U-Pb isotope analysis by LA-MC-ICP-MS has been conducted on zircon from two IMRs from the Recoudert and Montoume localities, and from a monzodiorite, a paragneiss, and two amphibolite samples of the basement to the impact structure. Zircon from the target rocks yielded mainly Neoproterozoic to Carboniferous ages (~924 to ~301 Ma) that can mostly be correlated to different stages of the geological evolution of the FMC. The monzodiorite also yielded a Permian age of 272 ± 12 Ma. Zircon from the IMRs, and especially from the Montoume sample, gave a comparatively higher diversity of Neoproterozoic to Jurassic ages (~552 to ~195 Ma). Provenance analysis for the zircon age populations of the impactites compared to those of the basement rocks shows overall poor correlation between the two age groups. This suggests that other target lithologies were involved in the formation of these impact melts as well. Post-Variscan and preimpact ages (281–226 Ma) obtained for both melt rocks probably reflect a previously unconstrained event in the evolution of the regional geological history. Ages similar to the currently most widely accepted impact age of ~204–206 Ma were obtained from both IMR samples. In addition, the Montoume melt rock yielded several post-204 Ma ages, which might reflect a to date unconstrained, about 194 Ma postimpact thermal/hydrothermal event.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 10","pages":"2718-2743"},"PeriodicalIF":2.2,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142430294","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":"Araguainha impact structure, Brazil: New insights into the geology of the central uplift","authors":"Carolinna da Silva Maia de Souza,&nbsp;Natalia Hauser,&nbsp;Wolf Uwe Reimold,&nbsp;Renato Borges Bernardes,&nbsp;Lucieth Cruz Vieira,&nbsp;Edi Mendes Guimarães,&nbsp;Manfred Gottwald","doi":"10.1111/maps.14236","DOIUrl":"10.1111/maps.14236","url":null,"abstract":"<p>Extensive, new outcrops along the MT-100 state road in the northern part of the central uplift of the 40-km diameter, 252–259 Ma old Araguainha impact structure, Central Brazil, have become available for investigation. They offer new insight into the contact relationships between the different lithologies and the genesis of different types of impact-related rocks, as well as the current level of erosion of the structure. Three types of impact melt rock (IMR) with different field relationships and compositions can now be distinguished: (1) Type-I of granitic composition and occurring mainly as veins and dikes, besides a few larger pods, in the central alkali granite core of the central uplift; (2) Type-II in the form of plastically deformed clasts of mainly highly silicious compositions in polymict impact breccia; and (3) Type-III, derived from partially melted conglomerate or sandstone precursors, and that occurs at selected sites in (meta)sedimentary strata of the basement in the immediate environs of the alkali granite core. Both polymict lithic and melt-bearing (suevitic) impact breccias are recognized in the 110-m thick integrated section through impact breccia directly overlying the crater floor. This crater floor is composed of (meta)-sedimentary basement strata with granite injections and, locally, sandstones of the Devonian sedimentary Furnas Formation of the Paraná Basin. Main breccia components are (meta)-pelites and (meta)sandstones of the basement that is currently favored to be related to the regional Paraguay Belt and to the lower sequence of the Paraná Basin sedimentary strata. Locally, breccia contains clasts of IMR Type-II, and only very rarely are granitic fragments observed. Clasts of IMR Type-I have never been observed in the breccia deposits. These new observations preclude significant involvement of alkali granite in the formation of the polymict breccia or in the production of shock melts. They also reveal the major role of the (meta)sedimentary precursors in the production of IMR by shock melting and provide essential information for better understanding the cratering processes involved in the formation of an impact structure in a sedimentary target, of the size of the Araguainha impact structure.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 10","pages":"2577-2607"},"PeriodicalIF":2.2,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141804165","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":"Impactor identification with spallogenic Cr isotopes: The Wabar impact craters (Saudi Arabia)","authors":"Aryavart Anand,&nbsp;Klaus Mezger,&nbsp;Beda Hofmann","doi":"10.1111/maps.14242","DOIUrl":"10.1111/maps.14242","url":null,"abstract":"<p>Precise measurements of Cr isotopic composition of terrestrial impactites have successfully provided evidence for the presence of extraterrestrial material and have, in some cases, allowed the identification of the type of impactor responsible for the formation of the impact structure. The high Cr abundance in most meteorite groups aids in detecting extraterrestrial contamination while their distinct isotopic compositions can help with the identification of the nature of the projectile. However, this common approach of detection and identification of extraterrestrial contamination using mass-independent ⁵³Cr and ⁵⁴Cr variations fails when the impactor type is an iron meteorite because of their low Cr abundances (which are in a similar range to terrestrial rocks). The present study demonstrates the viability of a spallogenic Cr contribution in iron meteorites (resulting from their long cosmic ray exposure times), which compensates for their low Cr abundances and facilitates the identification of iron-meteoritic contamination in terrestrial impactites. Thus, it broadens the scope of impactors (and impactites) that can be investigated using mass-independent Cr isotopes from solely chondrites and primitive achondrites to include iron meteorites. The Wabar impact craters are an optimal candidate for this study, characterized by low weathering, diverse impactites, partial meteorite survival, substantial impactor material contamination, and a felsic target lithology with low background Cr concentration. The Cr isotopic composition of the Wabar background sand, which represents the target lithology, is indistinguishable from the terrestrial Cr isotopic composition range, whereas the Wabar iron meteorites show coupled spallogenic excesses in ε⁵³Cr and ε⁵⁴Cr. The Cr isotopic compositions of Wabar impactites show resolved deviations from the terrestrial Cr isotopic composition, thereby indicating the presence of Wabar meteoritic contamination. Moreover, the study demonstrates that even an impactor with a non-carbonaceous chondritic origin, such as a IIIAB iron meteorite, can have a carbonaceous chondrite-like signature in ε⁵⁴Cr anomalies due to spallogenic Cr contamination. The study advocates for a comprehensive investigation combining platinum group elements and Cr (and/or Ni, Ru) isotopes to accurately characterize impactor types.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 10","pages":"2651-2659"},"PeriodicalIF":2.2,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14242","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141821322","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 “suevite” conundrum, Part 2: Re-examining the type locality at the Ries impact structure, Germany","authors":"Gordon R. Osinski,&nbsp;Richard A. F. Grieve","doi":"10.1111/maps.14241","DOIUrl":"10.1111/maps.14241","url":null,"abstract":"<p>One of the most common types of allochthonous impactite produced in hypervelocity impact events is impact breccia that contains melt particles. In numerous terrestrial hypervelocity impact structures such melt-bearing breccias have been termed “suevite,” after the type locality at the Ries impact structure, Germany. Despite its widespread occurrence, the origin, emplacement, and classification of suevite remains debated. In this contribution, we re-examine the nature and origin of suevite at the Ries impact structure. The results of new field and laboratory investigations, when combined and synthesized with results from previous studies, lead to a multi-stage model for the origin and emplacement of allochthonous impactites during the Ries impact event. Following the creation of a transient cavity the so-called Bunte Breccia and “megablocks” were emplaced via ballistic sedimentation and subsequent radial flow during the excavation stage to form a continuous ejecta blanket. At the end of the excavation stage, a mixture of melt and lithic fragments formed a lining to the transient cavity and it is this material that later became the crater, dike, and outer suevite (OS) units. The crater suevite represents the material from the displaced zone of the transient cavity that was transported and mixed but never left the cavity. The emplacement of dike suevite occurred during the modification stage as the crater suevite was intruded into fractures in the underlying crater floor. The OS and rare impact melt rocks overlying the ballistic (Bunte Breccia) ejecta deposits were emplaced as outwards-directed ground-hugging flows largely during the modification stage of crater formation. The OS flows varied both spatially and temporally in terms of the flow characteristics, from being dominated by solid particles and gas (cf. pyroclastic density currents) to a mixture of solid particles, liquid (impact melt), and minor gases (i.e., particulate impact melt-rich flows). These particulate impact melt-rich flows dominated by far. Minor “fallback” of material from an ejecta plume is evidenced by accretionary lapilli in the Nördlingen 1973 core. In summary, allochthonous impactites at the Ries impact structure are not unusual but are consistent with observations from other terrestrial and planetary craters, where melt-rich impactites overly ballistic ejecta deposits both outside and inside crater rims and where melt-rich impactites occur in crater interiors.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"59 10","pages":"2622-2650"},"PeriodicalIF":2.2,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.14241","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141832263","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}