Meteoritics & Planetary Science最新文献

{"title":"2025 Service Award for Rhiannon G. Mayne","authors":"Jemma Davidson, Catherine Corrigan","doi":"10.1111/maps.70009","DOIUrl":"https://doi.org/10.1111/maps.70009","url":null,"abstract":"<p>The Meteoritical Society Service Award selectee Dr. Rhiannon G. Mayne is recognized for over two decades of unrelenting dedication to the meteoritics and planetary science communities. Her widespread contributions have promoted research and education in meteoritics and planetary science through extensive education and public outreach activities, service to the broader scientific community, and the acquisition, classification, and curation of many new samples for research in the Monnig Collection.</p><p>Rhiannon earned her first degree in geology from Edinburgh University in 2002, followed by a Ph.D. from the University of Tennessee in 2008 under the tutelage of Hap McSween. Rhiannon then undertook a brief postdoctoral fellowship at the Smithsonian's National Museum of Natural History, where she worked with Tim McCoy and Cari Corrigan, before being appointed as the Oscar and Juanita Monnig Endowed Chair of Meteoritics and Planetary Science at Texas Christian University (TCU) in 2009. At the same time, Rhiannon was appointed the Curator of the Monnig Collection.</p><p>Rhiannon has, for her entire appointment at TCU, been the sole planetary scientist at her institution and the only employee who works with the Monnig Collection itself. In the last 16 years, Rhiannon has grown the Monnig Collection from less than 1500 classified meteorites to nearly 2500, and in 2014 completely recatalogued the Collection as many of the previous records were paper-based. These meteorites are available for scientific study, and the Monnig Collection, a once-hidden gem, has become increasingly visible under Rhiannon's stewardship.</p><p>Under Rhiannon's leadership, the Monnig Gallery has seen similar growth to the Monnig Collection. When Rhiannon joined TCU, the Gallery had a full-time Director who managed not only the budget and maintenance of the Gallery but also the public outreach. That position was eliminated in 2010, and Rhiannon assumed the role of Director in addition to her curatorial and professorial duties. In 2010, less than 4000 individuals came into contact with the Monnig Collection at public outreach events both off and on campus and during visits to the Gallery. Under Rhiannon's direction, and with the help of a part-time educator, that number rose to an astonishing 16,360 in 2018. The Gallery was closed during the early days of the COVID-19 pandemic and did not open again until June 2022. Since then, Rhiannon has seen thousands of individuals at public outreach events both on and off campus and welcomed many more to the Gallery as visitors during normal opening hours. All of this outreach is undertaken in addition to her work as Curator and an Associate Professor with a heavy teaching load.</p><p>As testament to her commitment to public engagement, Rhiannon undertook an Informal Learning in Museums Professional Certificate at Oregon State University to better understand how to maximize learning both for visitors to the Gallery and for those at outre","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 S1","pages":"359-361"},"PeriodicalIF":2.4,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.70009","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145022393","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":"Constraints on the fluid alteration of Nakhla meteorite inferred from Fe-rich phyllosilicate characterization","authors":"Isabella Pignatelli,&nbsp;Enrico Mugnaioli,&nbsp;Yves Marrocchi,&nbsp;Luigi Folco","doi":"10.1111/maps.70031","DOIUrl":"https://doi.org/10.1111/maps.70031","url":null,"abstract":"<p>The Nakhla Martian meteorite is known to contain secondary minerals, in particular phyllosilicates, that have recorded the conditions of aqueous alteration of the parent rock. A section of this meteorite was analyzed by transmission electron microscopy to characterize the phyllosilicates in veins and mesostasis. High resolution and electron diffraction, combined with chemical data, suggest the presence of veins in olivine filled by carbonates and hisingerite or hisingerite alone. In the mesostasis, phyllosilicates with composition close to that of ferripyrophyllite were observed in rounded pores within feldspars—these phyllosilicates are associated with areas rich in Si likely due to the presence of amorphous silica. Iron oxides/hydroxides were not found in this study. In addition, for the first time, wadsleyite was observed within the vein margins in olivine. Wadsleyite is evidence of shock metamorphism in Nakhla, whereas the veins result from the decompression after the shock wave passed through due to impact(s). The identification of these secondary minerals constrains the temperature, pH, and redox conditions during the aqueous alteration, underlying that these conditions changed over time. For example, hisingerite forms at <i>T</i> = 120–140°C and ferripyrophyllite at 55–65°C, confirming a progressive temperature decrease when the alteration went forward. The occurrence of these Fe-rich phyllosilicates has also implications on possible past life on Mars: H₂-fueled life cannot survive at <i>T</i> &gt; 122°C; thus, it is incompatible with the formation of hisingerite. Life could have been possible only during the last step of aqueous alteration, that is, when the temperature decreased and ferripyrophyllite formed.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 9","pages":"2197-2222"},"PeriodicalIF":2.4,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145102250","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":"Citation for Dr. Conel M. O'D. Alexander, Leonard Medalist, 2025","authors":"Larry R. Nittler","doi":"10.1111/maps.70026","DOIUrl":"https://doi.org/10.1111/maps.70026","url":null,"abstract":"&lt;p&gt;President Consolmagno, friends and colleagues of the Meteoritical Society, it gives me great pleasure to present Dr. Conel Michael O'Donel Alexander (Figure 1) of the Carnegie Institution of Washington as the 2025 recipient of the &lt;i&gt;Leonard Medal&lt;/i&gt;. Conel is honored for the fundamental and important contributions he has made to many aspects of meteoritics and allied fields, including the nature and origin of chondrite matrix, the origin of presolar grains, the nature and origin of water and organic matter in the Solar System, the origin of chondrules, and the origin of major cosmochemical trends across the Solar System. He has made these contributions using a vast array of analytical and modeling tools. I first met Conel in July 1991, on my first day of graduate school at Washington University in St. Louis, where Conel was a postdoc. He became an important mentor and eventually my longest-running and closest scientific collaborator and a dear friend. I therefore feel very privileged to provide this citation.&lt;/p&gt;&lt;p&gt;Conel's grandfather Hugh Alexander was a famous cryptologist who helped crack the Enigma code in World War II and a famous chess grandmaster. His father Michael Alexander was an Olympic medalist in fencing and an important British diplomat, among other things serving as diplomatic personal secretary to Prime Minister Margaret Thatcher. Conel inherited the formidable intellect of his parents and grandparents and we are fortunate he chose to apply it to investigating meteorites and the mysteries they hold. He earned a bachelor's degree in Geology from Imperial College in 1983 and his PhD in Experimental Physics from the University of Essex in 1987. For his doctoral work, he worked with Professor David Barber and with Dr Robert Hutchison (Natural History Museum, London), applying transmission electron microscopy to the matrix of ordinary chondrites. Application of TEM to meteorites was still relatively rare, and Conel made the ground-breaking discovery that the least altered ordinary chondrites contained clay minerals in their matrix, belying the belief at the time that OCs were bone dry. As Prof. Monica Grady stated in her nominating letter, this “discovery was the starting point of a career that has embraced a range of disciplines and techniques applied to a range of objects (meteorites, micrometeorites, Earth, Moon, Mars, asteroids, comets) in order to understand the range of processes that ultimately resulted in the Solar System.”&lt;/p&gt;&lt;p&gt;Presolar grains were discovered in carbonaceous chondrites in 1987 and immediately piqued Conel's interest. Upon receiving his PhD, he joined Colin Pillinger's group at the Open University where he learned stable isotope mass spectrometry, made acid residues of several ordinary chondrites, and used stepped combustion to show that both presolar grains and isotopically anomalous organic matter were present in them, not just in carbonaceous meteorites. In 1989, he moved to Washington University to wo","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 S1","pages":"356-358"},"PeriodicalIF":2.4,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.70026","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145022392","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":"Olivine fabric and microstructure in Northwest Africa (NWA) 7059 and Nova 018: Insights into ureilite deformation","authors":"A. I. Sheen,&nbsp;C. K. F. Tirona,&nbsp;K. T. Tait,&nbsp;L. F. White,&nbsp;B. C. Hyde,&nbsp;S. Korchinos","doi":"10.1111/maps.70028","DOIUrl":"https://doi.org/10.1111/maps.70028","url":null,"abstract":"<p>Olivine is a major constituent in ureilites and commonly defines macroscopic fabric via shape-preferred orientation of elongate grains. In this study, we examined olivine fabric (crystallographic preferred orientation, or CPO) and microstructures in the unbrecciated olivine-pigeonite ureilites Northwest Africa (NWA) 7059 and Nova 018 using electron backscatter diffraction (EBSD) analysis. Point-per-grain orientation data of NWA 7059 indicate a &lt;010&gt; lineation subparallel to grain elongation. Misorientation data of two grains in NWA 7059 indicate dominant activity of (010) [100], (001) [100], (100) [001], and {<i>hk</i>0} [001] slip systems. Nova 018 displays an axial-[010] fabric, with misorientations indicating (010) [001], {<i>hk</i>0} [001] slips, and formation of (010) twist boundaries. Axial-[010] fabric in Nova 018 is consistent with compaction of residual olivine during melt extraction. The &lt;010&gt; lineation in NWA 7059 is unlike typical ureilite fabric and requires a [010] Burgers vector, uncommon in terrestrial samples. Rotational axis analysis of 2°–10° misorientations in olivine shows that the relative proportion of [001] slips and [100] slips in both ureilites are similar to warm-shocked ordinary chondrites, which were deformed at subsolidus temperatures. However, subsolidus deformation temperatures for both studied ureilites are inconsistent with a “hot disruption” model for the ureilite parent body (UPB). The further lack of correlation between 2°–10° misorientation metrics and olivine core Fo content argues against deformation temperature as the main control on olivine slip systems in ureilites. Our findings highlight the use of olivine petrofabric to gain insights into ureilite deformation, as well as complexities in interpreting olivine deformation data with respect to the history of the UPB.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 9","pages":"2166-2183"},"PeriodicalIF":2.4,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.70028","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101960","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":"Secondary corundum-bearing assemblages in Allende Ca,Al-rich inclusions: Mineralogy, petrology, oxygen, and aluminum–magnesium isotope systematics","authors":"A. N. Krot,&nbsp;K. Nagashima,&nbsp;M. I. Petaev,&nbsp;E. Dobrică,&nbsp;C. Ma,&nbsp;B. Jacobsen","doi":"10.1111/maps.70036","DOIUrl":"https://doi.org/10.1111/maps.70036","url":null,"abstract":"<p>We report on the mineralogy, petrology, oxygen, and aluminum–magnesium isotopic systematics of the secondary corundum-bearing assemblages in type B CAIs <i>3529Z</i> and <i>3529G</i> and fluffy type A (FTA) CAI <i>ALH-2</i> from Allende (CV &gt; 3.6). In <i>3529Z</i> and <i>3529G</i>, 2–5 μm-sized euhedral-to-subhedral corundum grains associate with secondary alumoåkermanite [(Ca,Na)₂AlSi₂O₇], grossular, spinel, grossite, celsian, kushiroite, and wadalite. In <i>ALH-2</i>, 2–5 μm-sized euhedral-to-subhedral corundum grains associate with secondary grossular, nepheline, spinel, and kushiroite. In <i>3529Z</i> and <i>3529G</i>, corundum and associated secondary grossite, spinel, alumoåkermanite, grossular, and kushiroite have similar ¹⁶O-poor compositions (Δ¹⁷O = −2.2 ± 1.5‰); primary spinel is ¹⁶O-rich (Δ¹⁷O ~ −23‰); Al,Ti-diopside shows a range of Δ¹⁷O (from ~ −24‰ to ~ −15‰); anorthite and melilite are ¹⁶O-depleted to various degrees (−6.5‰ ≤ Δ¹⁷O ≤ −4.5‰ and Δ¹⁷O = −2.7 ± 0.8‰, respectively). In <i>ALH-2</i>, corundum shows a range of Δ¹⁷O, from ~ −9‰ to ~ −1‰; primary hibonite and spinel are ¹⁶O-rich (Δ¹⁷O ~ −23‰); melilite and perovskite are ¹⁶O-poor (Δ¹⁷O = −2.6 ± 1.5‰ and −3.1 ± 1.3‰, respectively). On the Al-Mg isotope diagram (²⁶Mg* versus ²⁷Al/²⁴Mg), primary Al,Ti-diopside, hibonite, melilite, and spinel in the Allende CAIs studied along the canonical isochron with inferred initial ²⁶Al/²⁷Al ratio [(²⁶Al/²⁷Al)₀] of ~5 × 10⁻⁵. All secondary minerals have resolved excesses of ²⁶Mg*: alumoåkermanite, corundum, and grossite plot below the canonical isochron, whereas most spinel analyses plot above it. An internal isochron defined by the coexisting secondary corundum and alumoåkermanite in <i>3529Z</i> has (²⁶Al/²⁷Al)₀ = (7.5 ± 2.6) × 10⁻⁷. We conclude that the corundum-bearing assemblages in Allende CAIs resulted from metasomatic alteration of primary melilite and anorthite, ~4–5 Ma after their crystallization. Metasomatic alteration of CAIs in the Allende parent asteroid by an aqueous fluid having Δ¹⁷O of ~ −3 ± 2‰ modified the O-isotope composition of their primary melilite, anorthite, and Ti-rich pyroxene; O-isotope compositions of primary hibonite, spinel, and low-Ti pyroxene escaped this modification.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 9","pages":"2239-2268"},"PeriodicalIF":2.4,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101961","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 sub-μm petrography of the observed meteorite fall Winchcombe—A complex array of pristine and altered chondrite components","authors":"Johannes Lier,&nbsp;Christian Vollmer,&nbsp;Linus Risthaus,&nbsp;Demie Kepaptsoglou,&nbsp;Quentin M. Ramasse,&nbsp;Aleksander B. Mosberg,&nbsp;Ashley J. King,&nbsp;Charlotte L. Bays,&nbsp;Paul F. Schofield","doi":"10.1111/maps.70027","DOIUrl":"https://doi.org/10.1111/maps.70027","url":null,"abstract":"<p>Samples of observed meteorite falls provide important constraints on alteration histories of Solar System materials. Due to its rapid collection, terrestrial alteration in the observed Mighei-type (CM) carbonaceous chondrite fall Winchcombe was minimal. In this work, the petrography and mineralogy of three Winchcombe lamellae, two from the matrix and one from a lithological clast, were analyzed by transmission electron microscopy. Our results demonstrate that the matrix of Winchcombe is dominated by Mg-Fe-rich serpentine-type phyllosilicates and tochilinite-cronstedtite intergrowth (TCI)-like phases with variable, but generally high (petrologic type 2.0–2.3) alteration degrees that agree with petrologic types acquired on TCIs on larger scales in other work. However, we also located pristine areas in investigated lamellae such as homogeneous amorphous silicates and glassy particles with sulfide and metal inclusions that resemble altered cometary GEMS (glass with embedded metal and sulfides). One distinct GEMS-like domain shows Fe-rich metal and sulfide grains with oxygen-enriched rims in a Mg-rich amorphous groundmass embedded in organic matter, which likely shielded it from more severe alteration. Fe-Ni-sulfides are mainly pentlandite and concentrated in matrix lamellae. In addition to the sub-μm scale brecciated texture, the three lamellae show different alteration extents, further demonstrating the complex alteration nature of this CM2 meteorite.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 9","pages":"2149-2165"},"PeriodicalIF":2.4,"publicationDate":"2025-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.70027","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145102320","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 late impact-induced metasomatism on the brachinite parent body recorded by a phosphate assemblage in NWA 7828","authors":"L. F. White,&nbsp;B. G. Rider-Stokes,&nbsp;M. Anand,&nbsp;R. Tartèse,&nbsp;J. R. Darling,&nbsp;G. Degli Alessendrini,&nbsp;R. Greenwood,&nbsp;K. T. Tait","doi":"10.1111/maps.70023","DOIUrl":"https://doi.org/10.1111/maps.70023","url":null,"abstract":"<p>Brachinites are a group of ultramafic achondritic meteorites thought to sample a planetesimal from the early inner solar system. They yield predominately ancient crystallization ages within 4 Ma of CAI formation, and while the formation mechanism for these samples is debated, they are widely thought to be partial melt residues from a differentiated planetesimal(s). Here, we conduct a correlated microstructural (electron backscatter diffraction; EBSD), trace element, and U–Pb age (laser ablation inductively coupled plasma mass spectrometry; LA-ICP-MS) study of a unique, large phosphate mineral assemblage in brachinite Northwest Africa (NWA) 7828 to constrain the origin and evolution of this sample and its parent body. Oxygen isotope analysis of NWA 7828 yields values in agreement with other brachinites and supportive of origin from the brachinite parent body. The phosphate assemblage is &gt;90% chlorapatite, with merrillite occurring around grain boundaries and within fractures that crosscut the larger crystal. All calcium phosphate grains are highly crystalline, with domains of chlorapatite displaying &lt;16° of internal misorientation, with merrillite displaying a range of unique orientations. When all concordant apatite and merrillite U-Th-Pb analyses are considered together, they yield a precise weighted average ²⁰⁷Pb-²⁰⁶Pb date of 4431 ± 5 Ma suggestive of a single population recording their crystallization age. Textural, chemical, and isotopic measurements of NWA 7828 are hard to reconcile with the formation of the phosphate assemblage in an igneous environment, instead supporting a metasomatic origin. The relatively younger age of the assemblage (4431 Ma) places it outside the estimated prolonged heating period on the brachinite parent body, instead requiring a later source of energy such as through impact-induced heating. This event coincides with the timing of impacts recorded by other brachinite (and brachinite-like) meteorites, as well as impact ages recorded by some Apollo melt breccias, and suggests a widespread, significant bombardment event around 4430 Ma.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 9","pages":"2099-2113"},"PeriodicalIF":2.4,"publicationDate":"2025-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.70023","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101928","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":"Level-2 processing of Chandrayaan-2 Imaging Infrared Spectrometer (IIRS) data for generation of surface reflectance","authors":"Mamta Chauhan,&nbsp;Prabhakar Alok Verma,&nbsp;Prakash Chauhan","doi":"10.1111/maps.70037","DOIUrl":"https://doi.org/10.1111/maps.70037","url":null,"abstract":"<p>Spectroscopy-based approach for remote exploration of any planetary body is significant in providing detailed understanding of surface composition, vital to any scientific exploration. Imaging Infrared Spectrometer (IIRS) is a hyperspectral imaging sensor flown over ISRO's Chandrayaan-2 (Ch-2) orbiter for mapping mineral composition and complete characterization of hydration feature on the lunar surface. With the extended spectral range (0.8–5 μm), high-spatial resolution (80 m) and high signal-to-noise ratio, IIRS data are capable of measuring surface composition based on diagnostic spectral absorption features of known/unknown characteristic minerals present on the lunar surface. The present paper discusses for the first time the methodology to process Ch-2 IIRS data to generate photometrically corrected reflectance images after thermal correction. Spectrally and radiometrically calibrated Level-1 IIRS spectral radiance data were subjected to various data processing techniques including thermal emission correction beyond 2.5 μm, conversion to apparent reflectance, and empirical line correction for smoothing the observed reflectance spectra. The thermally corrected IIRS reflectance data in the 0.8–3.3 μm range after correction for standard geometry were calibrated with ground-based observations of the lunar surface from the Apollo 16 site to generate Level-2 product. The results generated for the selected study regions representing the dominant landforms of the Moon (Mare, Highland and Polar region) were analyzed based on overall spectral reflectance variation and prominent absorption features at particular wavelengths corresponding to their surface properties. Finally, the results were compared with observations from Chandrayaan-1 Moon Mineralogy Mapper (M³) data within the overlapping spectral range from the same region to validate the absolute reflectance of the IIRS. Overall, slight differences in reflectance have been observed in the spectral profile from both the sensors in the lower wavelength range attributed mainly due to differences in resolution and observation geometry. However, beyond 2 μm, the spectral slope variation could be clearly visible, possibly because of thermal contributions that have been removed efficiently in the case of Ch-2 IIRS spectra.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 9","pages":"2269-2282"},"PeriodicalIF":2.4,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101433","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":"Radioisotopic age constraints of the Cambrian Ritland impact structure, Norway","authors":"William R. Hyde,&nbsp;Steven J. Jaret,&nbsp;Gavin G. Kenny,&nbsp;Anders Plan,&nbsp;Elias J. Rugen,&nbsp;Martin J. Whitehouse,&nbsp;Sanna Alwmark","doi":"10.1111/maps.70035","DOIUrl":"https://doi.org/10.1111/maps.70035","url":null,"abstract":"<p>Secondary ion mass spectrometry U-Pb geochronology has been performed on zircon grains separated from impact melt rock from the 2.7 km-in-diameter Ritland impact structure, southwestern Norway. Scanning electron microscope-based imaging techniques, including electron backscatter diffraction analysis, reveal various zircon grain microtextures, including shock-recrystallization and high-temperature zircon decomposition. Analyses from unshocked zircon grains yield two distinct concordant age populations at 1.5 and ~2.5 Ga, interpreted to represent igneous crystallization ages. The former aligns with Telemarkian magmatism (1.52–1.48 Ga) which dominates the local area of the Sveconorwegian orogeny and the target sequence at Ritland. The latter indicates a more ancient zircon population in Southern Norway, representing detrital grains in cover sediments present at the time of impact in the Cambrian. Collectively, the U-Pb data form two distinct discordant arrays with poorly resolved lower intercept ages spanning the Cambro-Ordovician boundary. The melt rock at Ritland is highly altered, and significant postimpact Pb loss is observed throughout the U-Pb data, likely in response to burial-induced thermal overprinting during the Caledonian orogeny. Post-filtering and selection of the data to minimize the effects of nonimpact-specific Pb loss, the two discordia produce indistinguishable lower intercept ages of 586 ± 73 Ma (MSWD 1.6, <i>n</i> = 15) and 545 ± 48 Ma (MSWD = 11, <i>n</i> = 9) which coincide in the Cambrian–Late Ediacaran. We therefore provide radioisotopic support for previous stratigraphic age constraints for the formation of the structure (500–542 Ma).</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 9","pages":"2223-2238"},"PeriodicalIF":2.4,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/maps.70035","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101342","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":"A terrestrial rock instead of an ureilite: Caution is recommended to scientists working on material received from meteorite collections","authors":"Lidia Pittarello,&nbsp;Stepan M. Chernonozhkin,&nbsp;Oscar Marchhart,&nbsp;Martin Martschini,&nbsp;Silke Merchel,&nbsp;Alexander Wieser,&nbsp;Frank Vanhaecke,&nbsp;Steven Goderis","doi":"10.1111/maps.70030","DOIUrl":"https://doi.org/10.1111/maps.70030","url":null,"abstract":"<p>Planetary scientists heavily depend on meteorite curation facilities for the preparation and allocation of protected (e.g., Antarctic), highly valuable extraterrestrial specimens. In this work, a fragment of the Dyalpur ureilite obtained from a museum is discussed. The sample is found to contain microstructural, geochemical, and isotopic features inconsistent with any meteorite. The fragment consists of pargasitic amphibole, Ni-sulfides, and chromite grains in Fo₉₂ olivine groundmass, cut by serpentine veins. Amphibole geothermobarometry yields equilibrium conditions that are not compatible with the assumed ureilite parent body. Assuming the fragment represented a rare clast in an ureilite, further analyses were performed. Both the oxygen isotopic composition and the extremely low level of cosmogenic radionuclides confirm the terrestrial origin of the fragment; it is a partially serpentinized peridotite. This work stresses the importance of petrographic characterization of samples used for (isotope) geochemical analyses, of a well-documented sample curation, and of cosmogenic nuclide measurements for the unequivocal identification of extraterrestrial material. Finally, caution is recommended before making sensational claims in cases of anomalous results.</p>","PeriodicalId":18555,"journal":{"name":"Meteoritics & Planetary Science","volume":"60 9","pages":"2283-2292"},"PeriodicalIF":2.4,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101254","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}