¹Stavrinos, George,¹Chatzitheodoridis, Elias,¹Sykioti, Olga
Studies in Computational Intelligence 1051, 177-225 Link to Article [DOI 10.1007/978-3-031-09062-2_6]
¹National Observatory of Athens and National Technical University of Athens, Athens, Greece

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

¹Kimura, Yuki,²Tanaka, Kyoko K.,^3,4Inatomi, Yuko,⁵Aktas, Coskun,⁵Blum, Jürgen
Science Advances 9, eadd8295 Open Access Link to Article [DOI 10.1126/sciadv.add8295]
¹Institute of Low Temperature Science, Hokkaido University, Kita-19, Nishi-8, Kitaku, Sapporo, 060-0819, Japan
²Astronomical Institute, Tohoku University, 6-3 Aoba, Aoba-ku, Sendai, 985-8578, Japan
³Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Kanagawa, Sagamihara, 252-5210, Japan
⁴School of Physical Sciences, SOKENDAI (Graduate University for Advanced Studies), 3-1-1 Yoshinodai, Chuo-ku, Kanagawa, Sagamihara, 252-5210, Japan
⁵Institut für Geophysik und Extraterrestrische Physik, Technische Universität Braunschweig, Mendelssohnstr. 3, Braunschweig, D-38106, Germany

¹Yassir A. ABDU,²Abbasher M. GISMELSEED,³Atta G. ATTAELMANAN,⁴Muawia H. SHADDAD,⁵Frank C. HAWTHORNE
Meteoritics & Planetary Science (in Press) Link to Article [doi: 10.1111/maps.13988]
¹Department of Applied Physics and Astronomy, University of Sharjah, Sharjah, United Arab Emirates
²Department of Physics, Sultan Qaboos University, Muscat, Oman
³College of Arts, Sciences and Information Technology, University of Khorfakkan, Khorfakkan, United Arab Emirates
⁴Department of Physics, University of Khartoum, Khartoum, Sudan
⁵Department of Earth Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
Published by arrangement with John Wiley and Sons

The crystal structures of orthopyroxene (En86.3Fs8.6Wo5.1, space group Pbca) and pigeonite (En81.7Fs8.8Wo9.5, space group P21/c) from the Almahata Sitta ureilite (fragment#051) have been refined to R1 indices of 3.10% and 2.53%, respectively, using single-crystal X-ray diffraction data. The unit formulas were calculated from electron microprobe analysis, and the occupancies at the M1 and M2 sites were refined for both pyroxenes from the single-crystal diffraction data. The results indicate a rather disordered intracrystalline Fe2+-Mg cation distribution over the M1 and M2 sites, with a closure temperature of 726(±55)°C for orthopyroxene and 704(±110)°C for pigeonite, suggesting fast cooling of these pyroxenes. The Mössbauer spectrum of the Fe-Ni metal particles of Almahata Sitta ureilite (fragment#051) is dominated by two overlapping magnetic sextets that are assigned to Fe atoms in Si-bearing kamacite, and arise from two different nearest-neighbor configurations of Fe* (=Fe+Ni) and Si atoms in the bcc structure of kamacite; (8F*, 0Si) and (7Fe*, 1Si). In addition, the spectrum shows weak absorption peaks that are attributed to the presence of small amounts of cohenite [(Fe,Ni)3C], schreibersite [(Fe,Ni)3P], and an Fe-oxide/hydroxide phase. The fast cooling of pyroxene to the closure temperature (after equilibration at ~1200°C) and the incorporation of Si in kamacite can be interpreted as due to a shock event that took place on the meteorite parent body, consistent with the proposed formation history of ureilites parent body where a fast cooling has occurred at a later stage of its formation.

^1,2Yongli Xue,^2,3,4Jinting Kang,^5,4Shiyong Liao,⁶Runlian Pang,^2,3,4Huimin Yu,^2,3,4Zifu Zhao,⁷Zhaofeng Zhang,⁸Bingkui Miao,^5,3,4 Weibiao Hsu,^2,3,4Fang Huang 
Earth and Planetary Science Letters 613, 118171 Link to Article [https://doi.org/10.1016/j.epsl.2023.118171]
¹Key Laboratory of Gemological Design and Testing, School of Jewelry and Art Design, Wuzhou University, Wuzhou, 543002, China
²CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China
³Deep Space Exploration Laboratory, University of Science and Technology of China, Hefei 230026, China
⁴CAS Center for Excellence in Comparative Planetology, USTC, Hefei 230026, Anhui, China
⁵Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210023, China
⁶State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
⁷Research Center for Planetary Science, Chengdu University of Technology, Chengdu, 610059, China
⁸Institution of Meteorites and Planetary Materials Research, Key Laboratory of Planetary Geological Evolution, Guilin University of Technology, Guilin 541006, China
Copyright Elsevier

Howardite-Eucrite-Diogenite (HED) meteorites represent a large suit of crustal and sub-crustal rocks from the Vesta. This work presents systematic examination of the Ca isotope data on multiple varieties of HED meteorites for a better understanding of the magmatic evolution of the Vesta. Falls and finds possess similar Ca isotope compositions, and no correlation is observed between �44/40Ca and (Sr/Eu*)_n, indicating that terrestrial weathering effect on Ca isotopes is insubstantial. According to the data in literature, the inner solar system may have a homogeneous �44/40Ca and the average of inner solar system bodies (‰0.97±0.03‰) can approximate the composition of bulk silicate Vesta (BSV). Basaltic eucrites define a cluster in �44/40Ca (‰0.95±0.07‰, 2SD, N=15) that is higher than the terrestrial mid-ocean ridge basalts (‰∼0.85‰). Combined with partial melting and magma ocean differentiation modeling, the Ca isotope signatures suggest that eucrites represent the residual melts evolved from a magma ocean formed by primordial Vesta’s moderate-to-high degree melting (20-100%). Diogenites have distinguishingly higher �44/40Ca (‰1.18±0.15‰, 2SD, N=7) than the basaltic eucrites, which displays a negative correlation with the 1000×Lu/Ti ratio and a positive correlation with 1/Ca. However, magma ocean crystallization can only explain diogenites with �44/40Ca higher than 1.17‰, suggesting that diogenites have complicated petrogenesis and are not necessarily cogenetic with eucrites. Diogenites with ‰�44/40Ca<1.17‰ may result from magma-ocean-cumulate partial melts intruding the eucritic crust. Mixing models suggest that the eucritic component in these diogenites may be less than 10%. Two howardites have lower �44/40Ca of ‰0.80±0.04‰ and ‰0.86±0.05‰ than eucrites and diogenites. This signature may reflect the addition of carbonaceous chondritic materials due to impact brecciation.

¹E.Clave et al.(>10)
Journal of Geopyhsical Reearch (Planets)(in Press) Link to Article [https://doi.org/10.1029/2022JE007463]
¹CELIA, Université de Bordeaux, CNRS, CEA, Bordeaux, France
Published by arrangement with John Wiley & Sons

Perseverance explored two geological units on the floor of Jezero Crater over the first 420 Martian days of the Mars2020 mission. These units, the Máaz and Séítah formations, are interpreted to be igneous in origin, with traces of alteration. We report the detection of carbonate phases along the rover traverse based on laser-induced breakdown spectroscopy (LIBS), infrared reflectance spectroscopy (IRS), and time-resolved Raman (TRR) spectroscopy by the SuperCam instrument. Carbonates are identified through direct detection of vibrational modes of CO3 functional groups (IRS and TRR), major oxides content, and ratios of C and O signal intensities (LIBS). In Séítah, the carbonates are consistent with magnesite-siderite solid solutions (Mg# of 0.42-0.70) with low calcium contents (<5 wt.% CaO). They are detected together with olivine in IRS and TRR spectra. LIBS and IRS also indicate a spatial association of the carbonates with clays. Carbonates in Máaz are detected in fewer points, as: (i) siderite (Mg# as low as 0.03); (ii) carbonate-containing coatings, enriched in Mg (Mg# ∼0.82) and spatially associated with different salts. Overall, using conservative criteria, carbonate detections are rare in LIBS (∼30/2000 points), IRS (∼15/2000 points), and TRR (1 /150 points) data. This is best explained by (i) a low carbonate content overall, (ii) small carbonate grains mixed with other phases, (iii) intrinsic complexity of in situ measurements. This is consistent with orbital observations of Jezero crater, and similar to compositions of carbonates previously reported in Martian meteorites. This suggests a limited carbonation of Jezero rocks by locally equilibrated fluids.

¹L.Mandon et al. (>10)
Journal of Geopyhsical Research (Planets)(in Press) Link to Article [https://doi.org/10.1029/2022JE007450]
¹LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, Meudon, France
Published by arrangement with John Wiley & Sons

The Perseverance rover landed in the ancient lakebed of Jezero crater, Mars on February 2021. Here we assess the mineralogy of the rocks, regolith, and dust measured during the first year of the mission on the crater floor, using the visible and near-infrared spectrometer of SuperCam onboard the Perseverance rover. Most of the minerals detected from orbit are present in the bedrock, with olivine-bearing rocks at the bottom of the stratigraphy and high-Ca pyroxene-bearing rocks at the top. This is distinct from the overall low-Ca pyroxene-bearing composition of the watershed of Jezero, and points towards an igneous origin. Alteration mineral phases were detected in most of the rocks analyzed in low proportions, suggesting that aqueous alteration of the crater floor has been spatially widespread, but limited in intensity and/or time. The diverse aqueous mineralogy suggests that the aqueous alteration history of the crater floor consists of at least two stages, to form phyllosilicates and oxyhydroxides, and later sulfates. We interpret their formation in a lake or under deeper serpentinization conditions, and in an evaporative environment, respectively. Spectral similarities of dust with some rock coatings suggest widespread past processes of dust induration under liquid water activity late in the history of Jezero. Analysis of the regolith revealed some local inputs from the surrounding rocks. Relevant to the Mars Sample Return mission, the spectral features exhibited by the rocks sampled on the crater floor are representative of the diversity of spectra measured on the geological units investigated by the rover.

¹Pei Ma,^1,2Hao Zhang,³Yazhou Yang,¹Te Jiang,⁴Daniel Britt,⁵Menghua Zhu
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2023.115608]
¹School of Earth Sciences, China University of Geosciences, Wuhan, China
²CAS Center for Excellence in Comparative Planetology, Hefei, China
³National Space Science Center, Chinese Academy of Sciences, Beijing, China
⁴University of Central Florida, Orlando, FL, USA
⁵State Key Laboratory of Lunar and Planetary Science, Macau University of Science and Technology, Macau
Copyright Elsevier

As a new planetary remote sensing tool, the phase ratio imagery calculates the ratio of images taken at different phase angles and may suppress surface albedo variations and enhance surface texture features. This technique has been used in the study of surface structure of airless bodies such as the Moon and Mercury. To understand the effectiveness of the method, we carried out laboratory phase ratio measurements on eight planetary analog materials including four pure minerals olivine, orthopyroxene, labradorite, ilmenite and four mixtures, the lunar regolith simulant JSC-1A, the lunar highland simulant, the Martian soil simulant, and the CI asteroid simulant, all in two size distributions, 0–45 μm and 90–105 μm. For each sample, the phase ratio A(α1)/A(α2) is obtained by measuring the reflectance at two phase angles α1 and α2 with α1<α2 at two radiation wavelengths, 633 nm and 905 nm. The results show that: (1) The particle size distributions can be differentiated by measuring the phase ratio A(α1)/A(α2), and in order to increase the discriminative power of the particle size distribution, the value of (α1-α2) should be as large as possible. (2) For pure minerals, larger grains have smaller phase ratio values, because larger grains of pure minerals are more forward scattering, leading to larger A(α2) and thus smaller phase ratio. For mixtures with simulated agglutinates that hold minerals together as composite particles, larger grains have higher phase ratios because they are less forward scattering due to multiple internal reflections and hence more absorptions. Since real planetary regoliths are likely dominated by composite particles with agglutinates, it is expected that larger grains would have larger phase ratio values.

^1,2Robert W. Nicklas,¹James M. D. Day,³Zoltán Váci,⁴Minghua Ren,⁵Kathryn G. Gardner-Vandy,⁶Kimberly T. Tait
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2023.04.019]
¹Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, 92093, USA
²Department of Earth and Environmental Sciences, Boston College, Chestnut Hill, MA, 02467, USA
³Department of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, MO, 63130, USA
⁴Department of Geoscience, University of Nevada, Las Vegas, Las Vegas, NV, 89154, USA
⁵Aviation and Space, Oklahoma State University, Stillwater, OK, 74078, USA
⁶Department of Natural History, Royal Ontario Museum, Toronto, ON, M5S 2C6, Canada
Copyright Elsevier

Metal-silicate segregation is one of the most fundamental mechanisms in planetary differentiation, with primitive achondrites offering important constraints on this process. Brachinites and brachinite-like achondrites (BLA) are olivine-dominated primitive achondrites that experienced up to ∼20% partial melt removal under relatively oxidized (ΔIW∼-1) conditions within an initially chondritic parent body and represent residues with inefficient metal-loss. We present bulk rock and in situ lithophile and highly siderophile element (HSE) abundance systematics as well as ¹⁸⁷Re-¹⁸⁷Os data for five olivine-rich primitive achondrites. These new data confirm classification of Reid 013 as a brachinite, three of the samples as BLA (Northwest Africa [NWA] 6874, NWA 7499, and Miller Range 090805), and the final sample as an ungrouped primitive olivine-rich achondrite (NWA 7680). An aliquot of MIL 090805 shows amongst the highest total HSE contents (>35 ppm) and the highest Pt content (∼23 ppm) of any primitive achondrite. Compiled HSE data for brachinites and BLA show correlations between total HSE abundance, Pt enrichment, and average olivine Fo. This correlation can be explained by variable melting (∼10-20%) of an H ordinary chondrite-like protolith, with retention of both Fe-metal and a Pt-rich alloy phase distinct from the observed Fe-metal phases in more depleted residues. Such a Pt-alloy phase is likely stabilized by elevated abundances of the HSE during chondrite melting and the low solubility of HSE in melts. Rhenium-Os isotope data in the studied samples has been modified by recent mobilization of Re during terrestrial weathering, with the limited range of measured ¹⁸⁷Os/¹⁸⁸Os in brachinites and BLA supporting minor fractionation of Re/Os during melting and an ancient (∼4.5 Ga) partial melting event to explain their compositions. These results indicate that models of planetary differentiation should consider the low solubility of Pt in chondrite melts and the potential for alloy formation to modify HSE abundances of silicate mantles.

¹Pierre-Marie Zanetta,^1,2Venkateswara Rao Manga,¹Yao-Jen Chang,²Tarunika Ramprasad,¹Juliane Weber,³John R. Beckett,^1,2Thomas J. Zega
American Mineralogist 108, 881-902 Link to Article [http://www.minsocam.org/msa/ammin/toc/2023/Abstracts/AM108P0881.pdf]
¹Lunar and Planetary Laboratory, The University of Arizona, Tucson, Arizona 85721, U.S.A.
²Materials Science and Engineering, The University of Arizona, Tucson, Arizona 85721, U.S.A.
³Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, U.S.A.
Copyright: The Mineralogical Society of America

Calcium-aluminum-rich inclusions (CAIs) in chondritic meteorites are composed of refractory
minerals thought to be the first solids to have formed in the solar nebula. Among them, hibonite,
nominally CaAl12O19, holds particular interest because it can incorporate significant amounts of Ti
into its crystal structure in both Ti3+ and Ti4+ oxidation states. The relative amounts of these cations
that are incorporated reflect the redox conditions under which the grain formed or last equilibrated and
their measurement can provide insight into the thermodynamic landscape of the early solar nebula.
Here we develop a new method for the quantification of Ti oxidation states using electron energy-loss
spectroscopy (EELS) in an aberration-corrected scanning transmission electron microscope (STEM)
to apply it to hibonite.
Using a series of Ti-bearing oxides, we find that the onset intensity of the Ti L2,3 edge decreases with
increasing Ti-oxidation state, which is corroborated by simulated Ti-oxide spectra using first-principles
density-functional theory. We test the relationship on a set of synthetic hibonite grains with known
Ti4+/ΣTi values and apply the developed method on a hibonite grain from a compact type A inclusion
in the Northwest Africa (NWA) 5028 CR2 carbonaceous chondrite. The STEM-EELS data show that
the chondritic hibonite grain is zoned with a Ti4+/ΣTi ratio ranging from 0.78 ± 0.04 to 0.93 ± 0.04
over a scale of 100 nm between the core and edge of the grain, respectively. The Ti substitution sites
are characterized by experimental and calculated high-angle annular-dark-field (HAADF) images and
atomic-level EEL spectrum imaging. Simulated HAADF images reveal that Ti is distributed between
the M2 and M4 sites while Mg sits on the M3 site. Quantitative energy-dispersive X-ray spectroscopy
shows that this grain is also zoned in Al and Ti. The Mg distribution is not well correlated with that
of Ti and Ti4+/ΣTi at the nanoscale.
The spatial decoupling of the element composition and Ti-oxidation states suggests a multistage
evolution for this hibonite grain. We hypothesize that Ti and Mg were incorporated into the structure
during condensation at high temperature through multiple reactions. Transient heating, presumably
in the solar nebula, adds complexity to the crystal chemistry and potentially redistributed Ti and Mg.
Concurrently, the formation of oxygen vacancies as a result of a reducing gas, led to the reduction of
Ti4+ to Ti3+. The multiple defect reactions occurring in this single hibonite crystal preclude a simple
relationship between the Ti4+/ΣTi and the fO2 of formation. However, moving forward, these measurements are fundamental inputs for modeling of the thermodynamic conditions under which hibonite
formed in the early solar nebula.