J. Storz^a, M.P. Reitze^a, A.N. Stojic^a, I. Kerraouch^a,b, A. Bischoff^a, H. Hiesinger^a, T. John^c
Icarus (in Press)
Link to Article [https://doi.org/10.1016/j.icarus.2024.116189]
^aInstitut für Planetologie, University of Münster, Wilhelm-Klemm-Str. 10, D-48149 Münster, Germany.
^bBuseck Center for Meteorite Studies (BCMS), Arizona State University, Tempe, AZ 85827, USA.
^cFreie Universität Berlin, Institut für Geologische Wissenschaften, Malteserstr. 74-100, D-12249 Berlin, Germany.

Although C1 clasts in carbonaceous chondrites are usually mineralogically similar to CI chondrites, they often exhibit distinct chemical or isotope characteristics, indicating that the diversity of carbonaceous matter is larger than represented by currently known meteorites. Samples returned by the Hayabusa2 mission provide an excellent opportunity to directly compare remote sensing data with laboratory spectra and elaborate on meteorite-asteroid links.

We obtained reflectance spectra from 10 carbonaceous samples of extraterrestrial origin to identify spectral differences in the wavelength region between 2.5 and 16.5 μm. We investigated seven volatile-rich clasts, two CI chondrites, and a fragment from the asteroid Ryugu, recently returned by the Hayabusa2 mission. To obtain representative spectra from a lithology, we performed multiple analysis with an aperture size of 100 μm × 100 μm. Subsequently, spectral features were correlated with petrographic and chemical data.

The phyllosilicate composition of the investigated C1 and C2 clasts is on average more Fe-rich compared to bulk CI chondrites, which is spectrally reflected in lower Christiansen feature (CF)/Reststrahlenband (RB) ratios. Our results confirm previous studies that indicate that the band area of the OH absorption band at 2.7 μm is dependent on the phyllosilicate composition. A high Mg abundance in phyllosilicates leads to a stronger OH absorption band. Varying degrees of aqueous alteration cause mineralogic differences that are observable in the reflectance spectra. Either in form of a band center shift towards smaller or longer wavelengths, depending on the metal cation giving rise to the M-OH absorption band, and/or a generally weaker OH absorption band, and a broad Reststrahlen band (RB) at 10 μm, with two minor RBs emerging at 11.3 and 12 μm. In contrast, most C1 clasts show a single RB at ≈10 μm, and a constant OH band position at 2.70 μm. The abundance of minor constituents, such as sulfides and carbonates, can also affect the spectrum. Dolomite produces two diagnostic bands at 6.5 and 11.3 μm, whereas pyrrhotite, devoid of diagnostic bands in this wavelength region, increases the background while decreasing the RB intensity.

Our findings indicate that within a laboratory framework, subtle mineralogic differences among hydrated carbonaceous materials can be spectroscopically detected. The spectra of Ryugu sample A0008 show a distinctive OH absorption band, as seen in the globally retrieved data by the NIRS3 instrument for Ryugu (Kitazato et al., 2019). Under specific circumstances, micro-FTIR reflectance spectra can be qualitatively compared to remote sensing spectra, and help to further elaborate on meteorite-asteroid links.

Denton S. EBEL^1,2,3, Marina E. GEMMA^1,4, Samuel P. ALPERT^1,3, Jasmine BAYRON⁵, Ana H. LOBO⁶, and Michael K. WEISBERG^1,3,7
Meteoritics & Planetary Science (in Press)
Link to Article [https://doi.org/10.1111/maps.14191]
¹Department of Earth and Planetary Sciences, American Museum of Natural History, New York, New York, USA
²Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York, USA
³Department of Earth and Environmental Sciences, Graduate Center of the City University of New York, New York,
New York, USA
⁴Department of Geosciences, Stony Brook University, Stony Brook, New York, USA
⁵Department of Geography, Hunter College, City University of New York, New York, New York, USA
⁶Department Physics & Astronomy, University of California Irvine, Irvine, California, USA
⁷Department of Physical Sciences, Kingsborough College, City University of New York, Brooklyn, New York, USA
Published by arrangement with John Wiley & Sons

Abundances, apparent sizes, and individual chemical compositions of chondrules, refractory inclusions, other objects, and surrounding matrix have been determined for Semarkona (LL3.00) and Renazzo (CR2) using consistent methods and criteria on X-ray element intensity maps. These represent the non-carbonaceous (NC, Semarkona) and carbonaceous chondrite (CC, Renazzo) superclans of chondrite types. We compare object and matrix abundances with similar data for CM, CO, K, and CV chondrites. We assess, pixel-by-pixel, the major element abundance in each object and in the entire matrix. We determine the abundance of “metallic chondrules” in LL chondrites. Chondrules with high Mg/Si and low Fe/Si and matrix carrying opposing ratios complement each other to make whole rocks with near-solar major element ratios in Renazzo. Similar Mg/Si and Fe/Si chondrule–matrix relationships are seen in Semarkona, which is within 11% of solar Mg/Si but significantly Fe-depleted. These results provide a robust constraint in support of single-reservoir models for chondrule formation and accretion, ruling out whole classes of astrophysical models and constraining processes of chondrite component formation and accretion into chondrite parent bodies.

Vincent GUIGOZ ¹, Anthony SERET² , Marc PORTAIL¹ , Ludovic FERRIERE³,
Guy LIBOUREL^2,4, Harold C. CONNOLLY Jr^5,6,7 , and Dante S. LAURETTA⁶
Meteoritics & Planetary Science (in Press) Open Access
Link to Article [https://doi.org/10.1111/maps.14225]
¹DCNRS, CRHEA, Universite C^ote d’Azur, Valbonne, France
²Observatoire de la C^ote d’Azur, CNRS, Laboratoire Lagrange, Universite Cote d’Azur, Nice, France
³Natural History Museum Abu Dhabi, Abu Dhabi, United Arab Emirates
⁴Hawai‘i Institute of Geophysics and Planetology, School of Ocean, Earth Science and Technology, University of Hawai‘i at
Manoa, Honolulu, Hawai‘i, USA
⁵Department of Geology, Rowan University, Glassboro, New Jersey, USA
⁶Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA
⁷Department of Earth and Planetary Science, American Museum of Natural History, New York, New York, USA
Published by arrangement with John Wiley & Sons

Carbonates, as secondary minerals found in CM chondrites, have been widely employed for reconstructing the composition of the fluids from which they precipitated. They also offer valuable insights into the hydrothermal evolution of their parent bodies. In this study, we demonstrate that high-resolution cathodoluminescence (HR-CL) analyses of calcites derived from the brecciated Cold Bokkeveld CM2 chondrite can effectively reveal subtle compositional features and intricate zoning patterns. We have identified two distinct types of cathodoluminescence (CL) centers: a blue emission band (approximately 375–425 nm), associated with intrinsic structural defects, and a lower energy orange extrinsic emission (around 620 ± 10 nm), indicating the presence of Mn cations. These compositional variations enable discrimination between the calcite grain types previously designated as T1 and T2 in studies of CM chondrites. T1 calcites exhibit variable CL and peripheral Mn enrichments, consistently surrounded by a rim composed of Fe-S-rich serpentine–tochilinite assemblage. Conversely, T2 calcites display homogeneous CL and more abundant lattice defects. These polycrystalline aggregates of calcite grains, devoid of serpentine, contain Fe-Ni sulfide inclusions and directly interface with the matrix. We propose that changes in the Mn content of calcite (indicated by the intensity of orange CL emission) are influenced by variations in redox potential (Eh) and pH of the fluid phase. This proposed hydrothermal evolution establishes a parallel between terrestrial serpentinization followed by carbonation processes and the aqueous alteration of CM chondrites, warranting further exploration and investigation of this intriguing similarity.

^1,2Alan E. Rubin
Meteoritics & Planetary Science (in Press) Open Access
Link to Article [https://doi.org/10.1111/maps.14223]
¹Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, California, US
²Maine Mineral & Gem Museum, Bethel, Maine, USA
Published by arrangement with John Wiley & Sons

Type II chondrules have higher oxidation states than type I chondrules; in ordinary chondrites (OC), type II chondrules tend to be larger, richer in bulk Fe, and have higher densities than type I chondrules. Magnesian type IA chondrules tend to be richer in ¹⁶O than type II chondrules. Because the aerodynamic behavior of a particle is a function of the product of its size and density, type I and type II chondrules (or their precursors) were partly separated in the ordinary chondrite zone of the solar nebula prior to the accretion of OC parent asteroids. LL chondrites acquired a chondrule population with the highest type II/type I ratios, L chondrites acquired chondrules with an intermediate ratio, and H chondrites acquired chondrules with the lowest type II/type I ratios. This contributed to the observed differences among OC groups in oxidation state and O-isotopic composition: in going from H to L to LL, mean oxidation state increases and mean Δ¹⁷O values increase. Higher oxidation is marked by increases in the FeO contents of olivine, low-Ca pyroxene, chromite, and ilmenite; increases in the TiO₂ content of chromite; and increases in the Co content of kamacite.

^aJay Goguen, ^bAndrew Sharits, ^cAnn Chiaramonti, ^dThomas Lafarge, ^cEdward Garboczi
Icarus (in Press) Open Access
Link to Article [https://doi.org/10.1016/j.icarus.2024.116166]
^aSpace Science Institute, 4765 Walnut St STE B, Boulder, CO 80301, United States of America
^bUES, Inc. and Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force B, Fairborn, OH, United States of America
^cApplied Chemicals and Materials Division, National Institute of Standards and Technology, Boulder, CO 80305, United States of America
^dStatistical Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, United States of America

Samples of soils collected by the Apollo 11 mission (10084,2036) and the Apollo 14 mission (14163,940) were obtained from the NASA Curation and Analysis Planning Team for Extraterrestrial Materials (CAPTEM) program. The particle size, shape, and internal porosity were characterized in three dimensions (3D) using a combination of X-ray computed tomography (XCT) and mathematical analysis, with various size and shape parameters measured and calculated for each particle. High-resolution scanning electron microscopy (SEM) was used to image the particles that were too small for the two XCT instruments used. Similar characterization was carried out on samples of JSC-1A lunar soil simulant, updating a previous analysis. Approximately 14,000 lunar regolith particles and 128,000 JSC1-A particles, covering a wide range of size and shape, were characterized for this paper and the results stored in a publicly accessible database. This large number of particles enabled, for the first time, statistically valid particle shape distributions to be generated. The 3D shape distributions of the two regoliths and JSC-1A were quantitatively compared and it was found that the way particle shape and porosity depended on particle size was different between regolith and simulant. The measured size distribution of particles in the lunar soils was applied to estimate the relative contributions of different sizes to the ensemble average particle single scattering albedo and phase function. By linking our particle counts to published sieve weight fractions for the lunar samples, we find that ~80% of the total cross-section area is contributed by particles <20 μm diameter and ~ 50% by particles <8 μm diameter. The orientation-averaged two-dimensional projected areas of the actual regolith particles were computed so that this estimate was also based on real particle shapes. Such small sizes dominating the total cross-section area suggest that calculations of the elements of the scattering matrix for individual particles may be possible with modest computing capabilities leading to the development of improved models for the quantitative interpretation of remote sensing spectrophotometry and polarimetry. This 3D characterization and database will enable other computational work to be done with real lunar regolith particle shapes, including discrete element method mechanical modeling, packing simulations, further light scattering calculations, dust contamination modeling, and modeling of lunar rover interactions with collected and packed regolith particles.

^a,bYogita Kadlag, ^c,dAryavart Anand, ^eMario Fischer-Gödde, ^dKlaus Mezger, ^fKristoffer Szilas, ^gSteven Goderis, ^bIngo Leya
Icarus (in Press) Open Access
Link to Article [https://doi.org/10.1016/j.icarus.2024.116143]
^aGeosciences Division, Physical Research Laboratory, Navrangpura, Ahmedabad, Gujarat 380009, India
^bSpace Science and Planetology, Physics Institute, Universität Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
^cMax-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
^dInstitut für Geologie, Universität Bern, Baltzerstrasse 1+3, 3012 Bern, Switzerland
^eInstitut für Geologie und Mineralogie, University of Cologne, Zülpicher Straße 49b, 50674 Köln, Germany
^fDepartment of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, 1350 Copenhagen, Denmark
^gArchaeology, Environmental Changes, and Geo-Chemistry (AMGC) Research Group, Department of Chemistry, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium

The late addition of extra-terrestrial material may represent an important source of Earth’s volatiles. The composition of impactors can be reconstructed using ⁵⁴Cr abundances in impact related rocks preserved in the terrestrial record. The average ε⁵³Cr and ε⁵⁴Cr of Earth’s mantle determined from mantle rocks of 3.8 Ga to present are 0.03 ± 0.02 and 0.08 ± 0.04, respectively. Impact melt rocks and spherule beds linked to impact structures larger than 50 km that formed between 3.4 Ga and 66 Ma have ε⁵³Cr ranging from −0.04 to 0.17, and ε⁵⁴Cr ranging from −0.64 to 1.41. A carbonaceous chondrite-like impactor contribution dominated the Meso- to Paleoarchean spherule layers (> 3.0 Ga), whereas a mixed chondrite flux composed of carbonaceous and non‑carbonaceous chondrites, with a possible contribution of differentiated meteorites is observed in the younger spherule layers (2.5 Ga to 66 Ma). This likely reflects the break-up of distinct asteroid families through time. Although available impact materials are limited, the Cr isotope signatures of materials related to large impacts suggest a change in the composition of crater-forming impactors on Earth, from predominantly carbonaceous chondrite-like more oxidized material during the Archean to predominantly non‑carbonaceous -like more reduced and volatile poor material in recent times. Chromium isotopes suggest that not >0.01 wt% of CC-like material added to the Earth’s mantle after Archean. Thus, it is inferred that the mass accreted after 3.0 Ga contributed insignificantly to the water and other volatile element budget of the Earth.