Chemical and isotopic measurements of HIDALGO, a stoichiometrically pure hibonite inclusion found in the matrix of the Dar al Gani 027 meteorite, were conducted by secondary ion mass spectrometry to investigate its origin and evolution. HIDALGO is characterized by large mass-dependent isotope fractionations in O, Ca, and Ti, as well as large negative anomalies in neutron-rich Ca-48 and Ti-50, making it the newest member of the HAL-type FUN inclusions. The highly fractionated Ca and Ti isotopes but unfractionated Mg isotopes are consistent with HIDALGO being a residue from an extensive evaporation event, during which large fractions of initial Ca and Ti, and essentially all the initial Mg, in the precursor material were lost. HIDALGO appears to have incorporated live Al-26 at a higher level than other HAL-type inclusions, but still at a lower amount compared to the Solar System's initial Al-26 abundance typically found in non-FUN CAIs. Interestingly, the inferred Be-10 abundance in HIDALGO is comparable to the values observed in the majority of CV3 CAIs but similar to 2.5 times higher than those in HAL-type samples. HIDALGO's unusual Al-26/Al-27 and Be-10/Be-9 ratios, together with the Ca-48-Ti-50 anomalies, can be best explained by the formation of its precursor material in the isotopically heterogeneous solar nebula. Finally, large Li-7 excesses correlating with Be/Li were found in HIDALGO, a behavior that can be interpreted as due to in-situ decay of live Be-7. Charged particle spallation of initially Li-free HIDALGO can simultaneously account for the inferred Be-7 abundance and the measured Li elemental concentration. The consistency between the measurement and spallation calculation results provides support for the prior existence of Be-7 in HIDALGO, possibly produced by irradiation close to the Sun.

We have investigated different carbonate minerals (calcite, aragonite, and ankerite) from two meteorites with different shock metamorphic stages (Boriskino, CM2 - similar to S3-S4 and Murchison CM2.5-2.2 - S1-S2) using various electron microscope techniques. Our detailed transmission electron microscopy study shows that carbonates are valuable recorders of the shock metamorphic environment and help interpret shock metamorphic conditions on the chondrite parent asteroids. We show the occurrence of fine -scale complex microstructures (dislocations, modulations, mosaic blocks, and microfractures) in all carbonates analyzed, indicating that they were modified during deformation processes at a variable degree. The presence of shock features in all generations of carbonates (Type 0, 1, and 2) indicates that shock deformation event/(s) occurred after the precipitation of all types of carbonates. In Boriskino, the most shocked meteorite analyzed, carbonates record very distinct microstructures compared to Murchison, an unshocked or very weakly shocked sample. We divided these microstructures into two different categories as a function of the degrees of deformation, and several features could be used as diagnostic tools for low and high shock pressures in meteorites. Deformation features are pervasive in calcites, aragonites (Type 1 and 2 Ca carbonates), and ankerites from Boriskino. However, the abundance and distribution of these deformation features are minimal in all calcite crystals analyzed from Murchison and one Type 0 Ca carbonate from Boriskino. This suggests the presence of a correlation between these microstructural features and the degree of shock metamorphic stages of the samples analyzed. The low amount of deformation features in the Type 0 calcite from Boriskino could indicate that the least altered lithologies from Boriskino were not subject to high-intensity impacts.

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As part of an integrated consortium study, we have undertaken O, Cd, Cr, Si, Te, Ti, and Zn whole rock isotopic measurements of the Winchcombe CM2 meteorite. delta Zn-66 values determined for two Winchcombe aliquots are +0.29 +/- 0.05 parts per thousand (2SD) and +0.45 +/- 0.05 parts per thousand (2SD). The difference between these analyses likely reflects sample heterogeneity. Zn isotope compositions for Winchcombe show excellent agreement with published CM2 data. delta Cd-114 for a single Winchcombe aliquot is +0.29 +/- 0.04 parts per thousand (2SD), which is close to a previous result for Murchison. delta Te-130 values for three aliquots gave indistinguishable results, with a mean value of +0.62 +/- 0.01 parts per thousand (2SD) and are essentially identical to published values for CM2s. epsilon Cr-53 and epsilon Cr-54 for Winchcombe are 0.319 +/- 0.029 (2SE) and 0.775 +/- 0.067 (2SE), respectively. Based on its Cr isotopic composition, Winchcombe plots close to other CM2 chondrites. epsilon Ti-50 and epsilon Ti-46 values for Winchcombe are 3.21 +/- 0.09 (2SE) and 0.46 +/- 0.08 (2SE), respectively, and are in line with recently published data for CM2s. The delta Si-30 composition of Winchcombe is -0.50 +/- 0.06 parts per thousand (2SD, n = 11) and is essentially indistinguishable from measurements obtained on other CM2 chondrites. In conformity with petrographic observations, oxygen isotope analyses of both bulk and micromilled fractions from Winchcombe clearly demonstrate that its parent body experienced extensive aqueous alteration. The style of alteration exhibited by Winchcombe is consistent with relatively closed system processes. Analysis of different fractions within Winchcombe broadly support the view that, while different lithologies within an individual CM2 meteorite can be highly variable, each meteorite is characterized by a predominant alteration type. Mixing of different lithologies within a regolith environment to form cataclastic matrix is supported by oxygen isotope analysis of micromilled fractions from Winchcombe. Previously unpublished bulk oxygen isotope data for 12 CM2 chondrites, when combined with published data, define a well-constrained regression line with a slope of 0.77. Winchcombe analyses define a more limited linear trend at the isotopically heavy, more aqueously altered, end of the slope 0.77 CM2 array. The CM2 slope 0.77 array intersects the oxygen isotope field of CO3 falls, indicating that the unaltered precursor material to the CMs was essentially identical in oxygen isotope composition to the CO3 falls. Our data are consistent with earlier suggestions that the main differences between the CO3s and CM2s reflect differing amounts of water ice that co-accreted into their respective parent bodies, being high in the case of CM2s and low in the case of CO3s. The small difference in Si isotope compositions between the CM and CO meteorites can be explained by different proportions of matrix versus refractory silicates. CMs and COs may also be indistinguishable with respect to Ti and Cr isotopes; however, further analysis is required to test this possibility. The close relationship between CO3 and CM2 chondrites revealed by our data supports the emerging view that the snow line within protoplanetary disks marks an important zone of planetesimal accretion.

The delivery of water to the inner Solar System, including Earth, is still a debated topic. A preferential role for hydrated asteroids in this process is supported by isotopic measurements. Carbonaceous chondrite (CC) meteorites represent our main source of information about these volatile-rich asteroids. However, the destruction of weaker materials during atmospheric entry creates a bias in our CC data. The return of surface materials from the C-type asteroid 162173 Ryugu by the Hayabusa2 spacecraft provides a unique opportunity to study high-porosity, low-density, primitive materials, unrepresented in the meteorite record. We measured the bulk oxygen isotope composition from four Ryugu particles and show that they most closely resemble the rare CI (CC Ivuna-type) chondrites, but with some differences that we attribute to the terrestrial contamination of the CI meteorites. We suggest that CI-related material is widespread among carbonaceous asteroids and a more important source of Earth’s water and other volatiles than its limited presence in our meteoritic collection indicates.

C-type asteroids are the source of the carbonaceous chondrite meteorites and represent remnants of primitive planetesimals that formed at the outer margins of the early Solar System and may have delivered volatiles to the inner Solar System, in particular the early Earth. However, the nature of carbonaceous chondrites is not well understood owing to terrestrial alteration. Here, we present the petrology and mineral chemistry of surface materials collected by the Japan Aerospace Exploration Agency (JAXA) Hayabusa2 spacecraft from the C-type asteroid Ryugu. The Ryugu particles we studied are similar to CI (Ivuna-type) chondrites but with some important differences, such as the presence of Na–Mg phosphates and Na-rich phases and the lack of ferrihydrite and gypsum. Ryugu particles experienced several steps of aqueous alteration, metasomatism and brecciation under variable conditions. These materials represent mixed lithologies and formed at different locations within their parent asteroid. The evidence presented here demonstrates that the C-type asteroid Ryugu experienced a complex geologic evolution shortly after its formation. The returned samples from Hayabusa2 show that C-type asteroid Ryugu experienced various steps of mineralogical alteration within only 1–2 million years after accretion.

Samples from asteroid Ryugu returned by the Hayabusa2 mission contain evidence of extensive alteration by aqueous fluids and appear related to the CI chondrites. To understand the sources of the fluid and the timing of chemical reactions occurring during the alteration processes, we investigated the oxygen, carbon and 53Mn–53Cr systematics of carbonate and magnetite in two Ryugu particles. We find that the fluid was initially between 0 and 20 °C and enriched in 13C, 17O and 18O, and subsequently evolved towards lighter carbon and oxygen isotopic compositions as alteration proceeded. Carbonate ages show that this fluid–rock interaction took place within approximately the first 1.8 million years of Solar System history, requiring early accretion either in a planetesimal less than ∼20 km in diameter or within a larger body that was disrupted and reassembled. The aqueous activity responsible for carbonate formation on Ryugu happened much earlier—less than 1.8 million years after CAI formation—than estimates (4–6 Myr) from carbonaceous chondrite meteorites. Ryugu’s parent body either was smaller than ∼20 km in diameter or was disrupted before reaching the high temperatures required.

Calcium-aluminum-rich inclusions (CAIs) are highly refractory objects found in different chondrite groups and represent some of the oldest known solids of the Solar System. As such, CAIs provide key information regarding the conditions prevailing in the solar protoplanetary disk as well as subsequent mixing and transport processes. Many studies have investigated CAIs for their isotopic compositions and reported nucleosynthetic isotope anomalies in numerous elements, which are typically explained by the variable incorporation of isotopically highly anomalous presolar phases. However, with the exception of 54Cr-enriched nanospinels, the exact presolar phases responsible for the isotopic heterogeneities are yet to be identified. To address this issue, we here present in-situ Ti isotopic analyses obtained on a diverse set of CAIs from various CV3 chondrites. The in-situ measurements were performed by targeting individual mineral phases of 15 CAIs with laser-ablation mass spectrometry and indicate significant inter- and intra-CAI isotopic heterogeneity in the neutron-rich isotope 50Ti. This is particularly pronounced for primitive fine-grained CAIs, whereas coarse-grained CAIs, which have been subject to melting, exhibit smaller degrees of Ti isotopic heterogeneity. To further investigate this Ti isotopic heterogeneity, we additionally obtained Ti isotopic compositions of sequential acid leachates from two fine-grained and two coarse-grained CAIs derived from CV3 chondrites. In contrast to potential expectations from the first part of the study, we do not observe any significant intra-CAI Ti isotopic heterogeneity between the different leaching steps. The lack of intra-CAI Ti isotopic heterogeneity in the acid leachate samples of this study likely reflects that the leaching procedure is unable to efficiently separate the carriers of isotopically anomalous Ti in CAIs. By comparing the bulk CAI Ti isotope compositions with Ti isotope data for hibonite-rich objects from the literature, we find that the range of Ti isotope compositions recorded by CAIs from various chondrite groups can be accounted for by the averaging of hibonite grains. In turn, the variable Ti isotope compositions of hibonite grains can be explained by the averaging of isotopically diverse presolar grains present in the Sun's parental molecular cloud. This effect of averaging is statistically supported by the central limit theorem, and the concept has the potential to be useful for other isotopic systems.

C-type asteroids likely formed in the outer Solar System and were then scattered inwards during giant planet migration (Walsh et al., 2011). They may have transported volatiles to the inner Solar System and created the conditions suitable for life on Earth(Alexander, 2017). Carbonaceous chondrites are fragments from C-type asteroids and provide evidence that these generally organic-rich (Garvie and Buseck, 2007) bodies experienced extensive aqueous alteration early in Solar System history (Alexander et al., 2014). On 6th December 2020, ~5.4g of material was delivered to Earth from the C-type asteroid 162173 Ryugu by the Hayabusa2 spacecraft (Yada et al., 2021). Here we present the results of an integrated bulk and micro-analytical study of Ryugu particles, which provides a unique insight into the interrelationship between aliphatic-rich organics and surrounding hydrous minerals at a sub-micrometer scale. This dataset has clear implications for better understanding the origin and early evolution of Solar System organic matter and demonstrates that Ryugu particles are among the most uncontaminated extraterrestrial materials so far studied.

The abundant phyllosilicate and carbonate minerals characterizing most of the returned particles from asteroid Ryugu suggest a history of extensive aqueous alteration on its parent body, similar to the rare mineralogically altered, but chemically primitive, CI (Ivuna-type) chondrite meteorites. Particle C0009 differs mineralogically from other Ryugu particles examined so far by containing anhydrous silicates at a level of ~0.5 vol%, and thus can help shed light on the unaltered original materials that constituted Ryugu’s protolith. In situ oxygen isotope measurements of the most Mg-rich olivine and pyroxene in C0009 reveal two populations of Δ17O: −25‰ to −15‰ and −8‰ to −3‰. The former and the latter populations correlate well with silicate morphologies similar to those seen in amoeboid olivine aggregates and chondrule phenocrysts, respectively, both of which are abundant in less aqueously altered carbonaceous chondrites. This result also highlights the presence of olivine with Δ17O close to the solar value in either a CI chondrite or an asteroid with CI-chondrite characteristics, and provides strong evidence that amoeboid olivine aggregates and Mg-rich chondrules accreted into Ryugu’s protolith. Our data also raise the possibility that the protoliths of CI and other carbonaceous chondrites incorporated similar anhydrous silicates. About 0.5% by volume of the Ryugu particle C0009 is made up of anhydrous silicates, mostly olivines, despite the extensive aqueous alteration of its parent body. Such aggregates, rich in 16O, were present in Ryugu’s protolith and survived fluid activity.

Abstract Samples from asteroid Ryugu returned by the Hayabusa2 mission contain evidence of extensive alteration by aqueous fluids and appear related to the CI chondrites. To understand the sources of the fluid and the timing of chemical reactions occurring during the alteration processes, we investigated the oxygen, carbon, and 53Mn-53Cr systematics of carbonate and magnetite in two Ryugu particles. We find that the fluid was initially between 0 − 20°C and enriched in 13C, and 17O and 18O, and subsequently evolved towards lighter carbon and oxygen isotopic compositions as alteration proceeded. Carbonate ages show that this fluid-rock interaction took place within the first ~ 1.4 million years of solar system history requiring early accretion and preservation of carbonaceous material, either in a planetesimal less than ~ 17 km in diameter or a larger body which was disrupted and reassembled.

Journal Article TEM Analyses of Carbonates from CM Chondrites - Possible Impact Events Revealed by Pervasive Microstructural Features Get access Elena Dobrică, Elena Dobrică University of Hawai'i at Mānoa, Hawai'i Institute of Geophysics and Planetology, School of Ocean, Earth Science, and Technology, Honolulu, HI, USA Corresponding author: dobrica@hawaii.edu Search for other works by this author on: Oxford Academic Google Scholar Kaitlyn A McCain, Kaitlyn A McCain University of California, Los Angeles, Department of Earth, Planetary, and Space Sciences, Los Angeles, CA, USA Search for other works by this author on: Oxford Academic Google Scholar Kevin D McKeegan, Kevin D McKeegan University of California, Los Angeles, Department of Earth, Planetary, and Space Sciences, Los Angeles, CA, USA Search for other works by this author on: Oxford Academic Google Scholar Adrian J Brearley Adrian J Brearley University of New Mexico, Department of Earth and Planetary Sciences, Albuquerque, NM, USA Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 28, Issue S1, 1 August 2022, Pages 2666–2668, https://doi.org/10.1017/S1431927622010108 Published: 01 August 2022

The Luskin Conference Center hosts a full-service hotel in which 200 rooms have been reserved at a reduced rate.All events will be within easy walking distance of Luskin, so there is no need to have a rental car for the week.Of course, there are many other lodging options in LA, with several near the UCLA campus (suggestions will be provided on the website).We are also seeking the possibility of dormitory accommodations for students or those on a tighter budget.Currently, there are no public health restrictions on gatherings in Los Angeles.We are planning for a mostly in-person meeting, with the possibility of remote participation via live on-line and in-schedule talks.Poster presentations will be in-person only.Transportation to UCLA from LA's main international airport (LAX) is straightforward.Los Angeles is a dynamic, multi-cultural city with myriad entertainment possibilities.Although hot spells are possible, the weather in mid-August is likely better than what you'll be leaving at home.The mountains, beaches, and wineries of southern and central California are readily accessed with a rental car for pre-or post-conference fun.We encourage you to reserve the dates of August 13-18 on your calendar today, and we look forward to welcoming you to Los Angeles in the summer of 2023!