¹Carine Sadaka,¹Jérôme Gattacceca,²Matthieu Gounelle,²Mathieu Roskosz,^1,3,4Anthony Lagain,⁵Romain Tartese,⁶Lydie Bonal,¹Clara Maurel,⁷Rodrigo Martinez,^8,9Millarca Valenzuela
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14307]
¹Aix-Marseille Université, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France
²Muséum National d’Histoire Naturelle, Institut de minéralogie, de physique des matériaux et de cosmochimie—UMR7590, Paris, France
³Aix-Marseille Université, Institut ORIGINES, Marseille, France
⁴Space Science and Technology Centre, School of Earth and Planetary Sciences, Curtin University, Perth, Western Australia, Australia
⁵Department of Earth and Environmental Sciences, The University of Manchester, Manchester, UK
⁶Institut de Planétologie et d’Astrophysique, Université Grenoble Alpes, Grenoble, France
⁷Museo del Meteorito, San Pedro de Atacama, Chile
⁸Universidad Católica del Norte, Antofagasta, Chile
⁹Center of Astrophysics and Associated Technologies CATA, Santiago, Chile
Published by arrangement with John Wiley & Sons

We present the outcome of search campaigns conducted in the Catalina Dense Collection area (DCA) located in the central depression of the Atacama Desert, Chile. The “Catalina Systematic Collection” (CSC) was assembled through systematic on-foot searches, resulting in a total of 1599 meteorites, before pairing, collected over a surface of 6.80 km2. This yielded a recovery density of 235 meteorites per km2 (67 meteorites >20 g per km2), making it the densest among hot deserts, even higher than the neighboring El Médano DCA collection. This confirms that the central depression of the Atacama Desert holds the highest meteorite density among hot deserts. We classified 457 meteorites weighing more than 20 g. After correcting for various recovery biases, we estimated a true meteorite density on the ground of 131 meteorites per km2 for meteorites >20 g before pairing. Using a probabilistic approach, we calculated an average pairing likelihood, yielding 71 meteorites >20 g per km2 after pairing. This high density is likely linked to an old age of the CSC, which would also explain the absence of carbonaceous chondrites, as they are more prone to alteration by abrasion. This long meteorite accumulation period is related to the long-term hyper-aridity and surface stability of the Atacama Desert, which have persisted for several million years. Meteorites from the CSC show less chemical weathering on average than in other hot deserts, despite the long accumulation period. The H/L ratio in the CSC is higher than in meteorites from other hot deserts, Antarctica, and falls, but similar to the El Médano collection, potentially reflecting variations in the composition of the meteorite flux over the past Myr.

^1,2G.K. Indu et al. (>10)
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14308]
¹Department of Geology, University of Kerala, Thiruvananthapuram, Kerala, India
²University College, Thiruvananthapuram, Kerala, India
Published by arrangement with John Wiley & Sons

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 <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.

^1,2Y. Li,^1,2P. J. A. McCausland,^1,2R. L. Flemming,^1,2G. R. Osinski
Meteoritics & Planetary Society (in Press) Link to Article [https://doi.org/10.1111/maps.14301]
¹Department of Earth Sciences, Western University, London, Ontario, Canada
²Institute for Earth and Space Exploration, Western University, London, Ontario, Canada
Published by arrangement with John Wiley & Sons

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, n = 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 (<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.

¹P. Ghaznavi,²C. Burkhardt,³F. L. H. Tissot,¹I. Leya
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14300]
¹Space Science and Planetology, Physics Institute, University of Bern, Bern, Switzerland
²Max-Planck Institut für Sonnensystemforschung, Göttingen, Germany
³Division of Geological and Planetary Sciences, The Isotoparium, Caltech, Pasadena, California, USA
Published by arrangement with John Wiley & Sons

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.

¹Pietro Demattê Avona,¹Alvaro Penteado Crósta,²Marcos Alberto Rodrigues Vasconcelos,^3,4Evan Bjonnes,¹Fernando Lessa Pereira,⁵Ana Maria Góes
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14306]
¹Institute of Geosciences, Universidade Estadual de Campinas, Campinas, SP, Brazil
²Institute of Geosciences, Federal University of Bahia, Salvador, BA, Brazil
³Lawrence Livermore National Laboratory, Livermore, CA, USA
⁴Lunar and Planetary Institute, Houston, TX, USA
⁵Institute of Geosciences, University of São Paulo, São Paulo, SP, Brazil
Published by arrangement with John Wiley & Sons

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.

¹Myriam Telus,^1,2Tyler D. Wickland,^1,3Kyle Kim,⁴Steven Simon
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14299]
¹Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, California, USA
²Geological Sciences, University of Colorado Boulder, Boulder, Colorado, USA
³Department of Geology, University of Maryland College Park, College Park, Maryland, USA
⁴Institute of Meteoritics, University of New Mexico, Albuquerque, New Mexico, USA
Published by arrangement with John Wiley & Sons

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 in situ 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.

¹Chi Ma,²Oliver Tschauner,¹John R. Beckett,³Vitali B. Prakapenka
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14302]
¹Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA
²Department of Geoscience, University of Nevada, Las Vegas, Nevada, USA
³Center for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois, USA
Published by arrangement with John Wiley & Sons

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.

¹Marina A. Ivanova,^2,3Sergey N. Britvin,⁴Roza I. Gulyaeva,⁴Sofia A. Petrova,⁵Nina G. Zinovieva,⁶Vladimir V. Kozlov,⁴Stanislav N. Tyushnyakov,⁷Anatoly V. Kasatkin
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14296]
¹Vernadsky Institute of Geochemistry of the Russian Academy of Sciences, Moscow, Russia
²Saint-Petersburg State University, St. Petersburg, Russia
³Kola Science Center, Russian Academy of Sciences, Apatity, Russia
⁴Institute of Metallurgy, Ural Branch, Russian Academy of Sciences, Yekaterinburg, Russia
⁵Lomonosov Moscow State University, Moscow, Russia
⁶Institute of Volcanology and Seismology, Far Eastern Branch of the Russian Academy of Sciences, Petropavlovsk-Kamchatsky, Russia
⁷Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia
Published by arrangement with John Wiley & Sons

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: Fe3+, Fe2+, and intermediate between Fe2+ and Fe0 involved in metallic-type Fe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)−, H2O or CO32− 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 Cmce (#64), a 17.4856(9), b 11.1516(5), c 11.1543(5) Å, V 2175.0(2) Å3, Z = 8, Dx = 4.11 g cm−3. The crystal structure has been solved and refined to R1 = 0.039 for 1105 unique reflections. Chemical composition of both natural and synthetic cafeosite corresponds to the formula Ca4Fe2+3Fe3+2(□1−xFex)O6S4 where (□1−xFex) denotes structural vacancy partially occupied by semimetallic-type Fe (x = 0.2–0.3). The ideal endmember formula of the mineral is Ca4Fe2+3Fe3+2□O6S4. 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 Fe3+ and Fe2+, 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–wüstite–pyrrhotite (IW-Po) and magnetite–wüstite–pyrrhotite (MW-Po) systems. Discovery of cafeosite provides insight into a previously obscured aspect of CY-chondrite formation: the redox conditions of thermal metamorphism on carbonaceous asteroids.

¹Zélia Dionnet et al. (>10)
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14304]
¹CNRS, Institut d’Astrophysique Spatiale, Université Paris-Saclay, Orsay, France
Published by arrangement with John Wiley & Sons

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.

^1,2L. Krämer Ruggiu,²B. Devouard,²J. Gattacceca,³L. Bonal,⁴L. Piani,⁵H. Leroux,⁶O. Grauby
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14295]
¹Archaeology, Environmental Changes and Geo-Chemistry, Vrije Universiteit Brussel, Brussels, Belgium
²CNRS, IRD, INRA, CEREGE, Aix Marseille Univ, Aix-en-Provence, France
³CNRS, IPAG, Univ. Grenoble Alpes, Grenoble, France
⁴CRPG, CNRS, Université de Lorraine, Vandoeuvre-les-Nancy, France
⁵CNRS, INRAE, Centrale Lille, UMR 8207 – UMET, Univ. Lille, Lille, France
⁶CNRS, CINaM, Aix-Marseille Université, Marseille, France
Published by arrangement with John Wiley & Sons

We studied Caleta el Cobre 022, a nakhlite showing a high abundance of aqueous alteration products, commonly called “iddingsite” and compared it to eight other nakhlites, in order to constrain the composition and the history of the aqueous alteration of nakhlites. Olivine grains in nakhlites display planes of secondary fluid inclusions, composed of pyroxene, magnetite, and a void potentially filled by a fluid. They were formed by a first fluid alteration event, previous to the iddingsite alteration event, probably from a late magmatic fluid circulation. We observed magnetite–pyroxene symplectites in olivine grains in most nakhlites, related to the same fluid-assisted tardi-magmatic event as the crystallization of the secondary inclusion planes. Those secondary inclusions and symplectites can be observed at the center of iddingsite veins, inside the most altered nakhlites, and are thus interpreted as being weakness planes, easing the circulation of the fluid forming the iddingsite inside the olivine grains. In every nakhlite, the alteration veins show at least two types of iddingsite: a coarse iddingsite with crystals around 50 nm, up to 200 nm, and a fine iddingsite with a nanocrystalline to amorphous texture with crystalline domains <10 nm. Both iddingsite types are composed mainly of Si, Mg, and Fe, with anticorrelated Si and Fe contents. The coarse iddingsite is composed of a mixture of phyllosilicates, with Fe-oxyhydroxides and minor siderite, and the fine iddingsite has a composition close to saponite. Organic matter located in coarse iddingsite is detected by Raman spectroscopy in the iddingsite of many nakhlites and was confirmed by the TEM study of NWA 10153. In addition, the TEM study of NWA 10153 displays complex chemical zoning in the fine iddingsite of Mg, Ca, Mn, S, P, and Al, suggesting at least two stages of circulations. Both the compositions and textures of the two types of iddingsite are suggestive of a progressive evolution of the alteration fluid, enriched in elements from basaltic mineral dissolution, with crystallization mainly by filling of existing fractures, and selective dissolution of host olivine. We also observe pyrrhotite–magnetite veinlets at the center of iddingsite veins and cross-cutting iddingsite veins and silicates, which are interpreted as the result of another later fluid circulation.