¹Cyrena A. Goodrich et al. (>10)
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13889]
¹Lunar and Planetary Institute, Universities Space Research Association, 3600 Bay Area Blvd., Houston, Texas, 77058 USA
Published by arrangement with John Wiley & Sons

MS-MU-012, a 15.5 g clast from the Almahata Sitta polymict ureilite, is the first known plagioclase-bearing main group ureilite. It is a coarse-grained (up to 4 mm), equilibrated assemblage of 52% olivine (Fo 88), 13% orthopyroxene (Mg# 89.2, Wo 4.5), 11% augite (Mg# 90.2, Wo 37.3), and 14% plagioclase (An 68), plus minor metal and sulfide. The plagioclase grains have been secondarily remelted and internally recrystallized, but retain primary external morphologies. Melt inclusions occur in olivine. Rounded chadocrysts of olivine and orthopyroxene are enclosed in augite grains. In terms of texture, mineralogy, major and minor element mineral compositions, and oxygen isotopes, MS-MU-012 is virtually identical to the archetypal Hughes-type main group ureilites, with the significant addition of primary plagioclase. We conclude that MS-MU-012 formed as a cumulate in a common lithologic unit with the Hughes-type ureilites. Based on reconstructed compositions of melts trapped in olivine, orthopyroxene, and augite in the Hughes-type samples, we infer that the parent magma of the Hughes unit originated as a late melt in the incremental melting of the ureilite parent body (UPB), near the end of the melting sequence, but was not completely extracted from the mantle like earlier melts and was emplaced in an intrusive body. MELTS calculations indicate that olivine began to crystallize at ~1260 °C, followed shortly thereafter by co-crystallization of orthopyroxene and augite. Plagioclase began to crystallize at ~1170–1180 °C. Graphite was buoyant in the melt and became heterogeneously distributed in flotation cumulates. Residual silicate liquid was extracted from the cumulate pile and could have crystallized to form the “labradoritic melt lithology” (with plagioclase of An ~68-35), which is partially preserved as clasts in polymict ureilites. The final equilibration temperature recorded by the Hughes unit was ~1140–1170 °C, just before catastrophic disruption of the UPB. MS-MU-012 provides a critical missing link in the differentiation history of this asteroid.

^1,2Peter Jenniskens,²Darrel Robertson,³Cyrena A. Goodrich,⁴Muawia H. Shaddad,⁴Ayman Kudoda,⁵Anna M. Fioretti,⁶Michael E. Zolensky
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.13892]
¹SETI Institute, 339 Bernardo Avenue, Mountain View, California, 94043 USA
²NASA Ames Research Center, Moffett Field, California, 94035 USA
³Lunar and Planetary Institute, USRA, Houston, Texas, 77058 USA
⁴Department of Physics and Astronomy, University of Khartoum, Khartoum, 11115 Sudan
⁵CNR–Istituto di Geoscienze e Georisorse, I-35131 Padova, Italy
⁶Astromaterials Research and Exploration Science, NASA Johnson Space Center, Houston, Texas, 77058 USA
Published by arrangement with John Wiley & Sons

Asteroid 2008 TC3 impacted the Earth’s atmosphere with a known shape and orientation. Over 600 meteorites were recovered at recorded locations, including meteorites of nonureilite type. From where in the asteroid did these stones originate? Here, we reconstruct the meteor lightcurve and study the breakup dynamics of asteroid 2008 TC3 in 3-D hydrodynamic modeling. Two fragmentation regimes are found that explain the lightcurve and strewn field. As long as the asteroid created a wake vacuum, the fragments tended to move into that shadow, where they mixed with small relative velocities and surviving meteorites fell along a narrow strip on the ground. But when the surviving part of the backside and bottom of the asteroid finally collapsed at 33 km altitude, it created an end flare and dust cloud, while fragments were dispersed radially with much higher relative speed due to shock–shock interactions with a distorted shock front. Stones that originated in this final collapse tended to survive in a larger size and fell over a wider area at locations on the ground. Those locations to some extent still trace back to the fragment’s original position in the asteroid. We classified the stones from this “large mass” area and used this information to glean some insight into the relative location of recovered ureilites and ordinary and enstatite chondrites in 2008 TC3.

¹Taha Shisseh,¹Hasnaa Chennaoui Aoudjehane,²Carl B. Agee,³Omar Boudouma
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13899]
¹GAIA Laboratory, Faculty of Sciences Ain Chock, Hassan II University of Casablanca, km 8 Route d’El Jadida, 20150 Casablanca, Morocco
²Institute of Meteoritics, University of New Mexico, Albuquerque, New Mexico, 87131 USA
³UPMC – Paris 06, UMR, 7193 Paris, France
Published by arrangement with John Wiley & Sons

Tirhert and Aouinet Legraa are the only documented unbrecciated eucrite falls in Africa. Aouinet Legraa fell in Algeria on July 17, 2013. Tirhert’s fall occurred about a year later in Morocco, on July 9, 2014. Both meteorites are covered by a black and glossy fusion crust as is typical of eucrites. Tirhert has a poikilitic texture with remnant subophitic pockets, and consists of millimeter-sized grains of plagioclase (An87-91), pigeonite (Mg# 42) with augite exsolution lamellae, and interstitial opaque minerals. Aouinet Legraa has a subophitic texture, and it is dominated by plagioclase laths (An82-89) enclosed by pigeonite (Mg# 37), with exsolution lamellae of augite. Remnant Ca zoning in pyroxene is observed in both rocks, although it is more abundant in Aouinet Legraa than Tirhert. The presence of exsolved pyroxenes suggests that these meteorites have undergone thermal metamorphism. Equilibration temperatures estimated from pigeonite and augite pairs using the QUILF program are ∼931 °C in Tirhert and ∼758 °C in Aouinet Legraa. This indicates that these rocks had distinct thermal histories. Aouinet Legraa has trace element abundances similar to the typical main group eucrite Juvinas, confirming its origin as a main group eucrite. The trace element abundances of Tirhert fall between those of cumulate and main group eucrites. Its rare earth element pattern is flat with a positive Eu anomaly. This likely suggests that Tirhert is a partial cumulate of plagioclase from a main group magma, or a flotation cumulate formed by flotation of plagioclase in a subvolcanic chamber or by scavenging crystals during eruption.

¹Yves Marrocchi,¹Maxime Piralla,¹Maxence Regnault,²Valentina Batanova,¹Johan Villeneuve,³Emmanuel Jacquet
Earth and Planetary Science Letters 593, 117683 Link to Article [https://doi.org/10.1016/j.epsl.2022.117683]
¹Université de Lorraine, CNRS, CRPG, UMR 7358, Vandœuvre-lès-Nancy 54500, France
²Université Grenoble Alpes, ISTerre, CNRS, UMR 5275, Grenoble 38000, France
³Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Muséum national d’Histoire naturelle, Sorbonne Université, CNRS; CP52, 57 rue Cuvier, 75005 Paris, France
Copyright Elsevier

Among primitive meteorites, CR chondrites have peculiar isotopic compositions, the origin of which is uncertain and may have involved contributions from primordial molecular cloud material or the chondrites’ formation and agglomeration late during the evolution of the protoplanetary disk. Here, we report a comprehensive textural and isotopic characterization of type I CR chondrules and provide new insights on their formation conditions. We find that two chondrule populations characterized by different sizes and oxygen isotopic compositions co-exist in CR chondrites. The typically larger, 16O-poor (-4‰) chondrules (type I-CR chondrules) appear to have formed late out of a CR reservoir already populated by typically smaller, 16O-rich (-4‰) chondrules (type I-CO chondrules). Before formation of type I-CR chondrules, the CR reservoir was likely dominated by CI-like dust, in line with the proximity of CR with CI chondrites for many isotopic ratios. The CR reservoir thus may have largely belonged to the continuum shown by other carbonaceous chondrites, although some isotopic ratios maintain some originality and suggest isotopic variation of CI-like dust in the outer disk. Combined with literature data, our data (i) demonstrates that recycling processes are responsible for the singular compositions of CR chondrites and their chondrules for isotopic systems with drastically different geochemical behaviors (O, Cr, Te) and (ii) support the homogeneous distribution of 26Al throughout the protoplanetary disk.

¹Lingzhi Sun,¹Paul Lucey
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2022.115204]
¹Hawai‘i Institute of Geophysics and Planetology, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA
Copyright Elsevier

Previous remote sensing studies focus on lunar surface regolith, which contains abundant mixtures of rock fragments and dust, making it hard to track the petrologic origin. Igneous boulders exposed on lunar surface, however, carry pristine mineralogy and chemistry since its formation, therefore are direct evidence of lunar thermal evolution events. High spatial-resolution remote sensing images and rover explorations of the Moon allow us to study the spectroscopy of igneous boulders. We modeled the optical scattering properties of rocks using the Legendre and Double Henyey–Greenstein phase functions, porosity parameter and grain size, and provided a modified radiative transfer model for rocks rather than powdered minerals. Considering that space weathering could generate a layer of dust or patina on the surface of boulders, we introduced a two-layer radiative transfer modeling algorithm to solve the spectroscopy of the substrate rock for dust- or patina-coated boulder. The modeled substrate rock spectra show less reddening, larger reflectance, and stronger absorption band depth compared to dust- or patina-coated rock, consistent with the measurements of Apollo rock samples. We applied this two-layer model on the dust-coated boulder detected by Yutu-2 rover and derived the spectrum of the substrate rock. Using Kaguya Multiband Imager data, we calculated the substrate rock spectra for an anorthosite boulder, and our result shows good consistency with laboratory measured anorthosite rock spectrum. This work is a beginning of understanding lunar boulder spectroscopy for a more precise interpretation of lunar thermal history.

¹S. N. Teplyakova,²M. Humayun,¹C. A. Lorenz,¹M. A. Ivanova
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13898]
¹Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Kosygina st. 19, 119991 Moscow, Russia
²National High Magnetic Field Laboratory and Department of Earth, Ocean & Atmospheric Science, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, Florida, 32310 USA
Published by arrangement with John Wiley & Sons

Isotopic compositions of O, Mo, and Cu in the IIE iron meteorites have indicated a close affinity to the H chondrite group. The diversity of trace element compositions and their abundance of silicate inclusions indicate that IIE iron meteorites were formed in multistage processes. To better constrain the formation of the IIE irons, this study analyzed elemental abundances in the metal of five IIE irons (Elga, Miles, Tobychan, Verkhne Dnieprovsk, and Watson) by laser ablation inductively coupled plasma mass spectrometry. The data are interpreted in terms of a new model of IIE crystallization from the metal fraction of completely molten H chondrite-like material based on the solid/liquid distribution coefficients of siderophile and chalcophile elements changing simultaneously with changes of S concentrations in the remaining liquid during the crystallization of the Fe,Ni phase in the Fe-Ni-S system. The model showed that IIE iron compositions could be produced as solid phases at 40–73 wt% of fractional crystallization of the metal component of a bulk H chondrite-like metallic melt. We propose that IIE iron metal could have originated from the solidified core of a differentiated body of H chondrite-like composition and sampled different fractions of that core exposed during a catastrophic disruption of the body. The present structure of metal and silicate inclusions of IIE irons was formed by remelting and metal–silicate mixing during late impact event(s) on the parent body surface.

¹A. Dixit,²R. P. Tripathi,³Sudhanshu Kumar,³Mohd. Azaj Ansari,³K. Sreenivas
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13888]
¹Department of Physics, Indian Institute of Technology, Jodhpur, 342037 India
²78, BGKT Extension Scheme, New Pali Road, Jodhpur, 342005 India
³Department of Physics and Astrophysics, University of Delhi, Delhi, 110007 India
Published by arrangement with John Wiley & Sons

Fourier transform infrared (FTIR) measurements on immediately collected Mukundpura show the typical feature for phyllosilicates around 10 μm, corresponding to Si-O stretching mode in silicate, and its broadness signifies the amorphous or poorly crystalline silicates. The absence of the 11.2 μm feature (a characteristic of anhydrous silicate olivine) and the weight loss observed in thermogravimetric analysis (TGA) imply aggressive aqueous alteration, which resulted in phyllosilicate formation at the expense of primary anhydrous silicates. It is consistent with Mössbauer spectra, showing the presence of both Fe2+ and Fe3+ in phyllosilicates, but no characteristic peak for olivine is observed, suggesting the major fraction of primary silicates are aggressively altered due to the presence of water on the parent body, and now major lithology must be highly altered. TGA measurements were carried on it (i) within 24 h and (ii) after 30 months of its fall. In both cases, the weight loss was ∼10% in the 400–770 °C temperature range, confirming the absence of any environmental impact on the water bound to the hydrated clay in Mukundpura samples. Appreciable weight loss in 400–770 °C indicated the presence of hydrated clay that corroborated FTIR measurements and ruled out any thermal event suffered by its postaqueous alteration, consistent with amorphous or poorly crystalline silicate phase observed in FTIR. When we couple the results of the present study and already reported results by our group on the same Mukundpura fragment, it is inferred that our sample has suffered a very high degree of aqueous alteration on the parent body. The fingerprint ratios, which are extensively used to correlate or assign petrological subgroup, are FeO/SiO2, hydrous silicate/anhydrous silicates, and MgO/FeO, which are either considered alone or in combination, and for Mukundpura, the values for these ratios are 1.05, 7.2, and ∼0.60, respectively. These values indicate that the major lithology of Mukundpura fresh fragment must be assigned as CM2.1.

¹Andreas Bechtold,¹Toni Schulz,¹Wencke Wegner,¹Dieter Mader,²Christian Patterer,¹Christian Koeberl
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.13894]
¹Department of Lithospheric Research, University of Vienna, UZA 2, Josef-Holaubek-Platz 2, 1090 Vienna, Austria
²Motrada Handels GmbH, Salesianergasse 31/11, 1030 Vienna, Austria
Published by arrangment with John Wiley & Sons

Lunar meteorite Northwest Africa (NWA) 11962 is a regolith breccia with a diverse range of mineral and lithic clasts. For the present study, major and trace element contents and selected isotopic compositions were determined on a homogenized bulk powder of NWA 11962 by instrumental neutron activation analysis, thermal ionization mass spectrometry, and inductively coupled plasma mass spectrometry. The chemical composition of the sample points toward an origin of the meteorite from within the Procellarum KREEP terrane (PKT). Samarium-Nd and Rb-Sr isotopic compositions and concentrations show a similarity to those of Apollo 15 soils and KREEP basalt. Highly siderophile element (HSE) abundances and ratios, as well as the Re/Os isotopic system, are often used as tracers of different impactor types. The 187Os/188Os and 187Re/188Os isotopic ratios are within the range of ordinary chondrites, yet some of the siderophile element and highly siderophile element ratios are comparable to those of iron meteorites. Using Fe, Th, and Ti abundances of lunar surface regolith, measured by the Lunar Prospector gamma-ray spectrometer, we attempt to constrain potential lunar source regions for NWA 11962. By matching these possible source regions with coordinates of recently (<1 Ma) formed lunar impact craters (so-called lunar cold spots), we localized a potential source crater of NWA 11962 at the western rim of the PKT close to Sinus Medii.

¹Sha Chen,¹Peng Ni,¹Youxue Zhang,²Joel Gagnon
American Mineralogist 107, 1519-1531 Link to Article [http://www.minsocam.org/msa/ammin/toc/2022/Abstracts/AM107P1519.pdf]
¹Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109, U.S.A.
²School of the Environment, University of Windsor, Windsor, Ontario N9B 3P4, Canada
Copyright: The Mineralogical Society of America

Mineral/melt partition coefficients have been widely used to provide insights into magmatic
processes. Olivine is one of the most abundant and important minerals in the lunar mantle and mare
basalts. Yet, no systematic olivine/melt partitioning data are available for lunar conditions. We report
trace element partition data between host mineral olivine and its melt inclusions in lunar basalts.
Equilibrium is evaluated using the Fe-Mg exchange coefficient, leading to the choice of melt inclusionhost olivine pairs in lunar basalts 12040, 12009, 15016, 15647, and 74235. Partition coefficients of
21 elements (Li, Mg, Al, Ca, Ti, V, Cr, Mn, Fe, Co, Y, Zr, Nb, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu)
were measured. Except for Li, V, and Cr, these elements show no significant difference in olivine-melt
partitioning compared to the data for terrestrial samples. The partition coefficient of Li between olivine
and melt in some lunar basalts with low Mg# (Mg# < 0.75 in olivine, or < ~0.5 in melt) is higher than published data for terrestrial samples, which is attributed to the dependence of DLi on Mg# and the lack of literature DLi data with low Mg#. The partition coefficient of V in lunar basalts is measured to be 0.17 to 0.74, significantly higher than that in terrestrial basalts (0.003 to 0.21), which can be explained by the lower oxygen fugacity in lunar basalts. The significantly higher DV can explain why V is less enriched in evolved lunar basalts than terrestrial basalts. The partition coefficient of Cr between olivine and basalt melt in the Moon is 0.11 to 0.62, which is lower than those in terrestrial settings by a factor of ~2. This is surprising because previous authors showed that Cr partition coefficient is independent of fO2. A quasi-thermodynamically based model is developed to correlate Cr partition coefficient to olivine and melt composition and fO2. The lower Cr partition coefficient between olivine and basalt in the Moon can lead to more Cr enrichment in the lunar magma ocean, as well as more Cr enrichment in mantle-derived basalts in the Moon. Hence, even though Cr is typically a compatible element in terrestrial basalts, it is moderately incompatible in primitive lunar basalts, with a similar degree of incompatibility as V based on partition coefficients in this work, as also evidenced by the relatively constant V/Cr ratio of 0.039 ± 0.011 in lunar basalts. The confirmation of constant V/Cr ratio is important for constraining concentrations of Cr (slightly volatile and siderophile) and V (slightly siderophile) in the bulk silicate Moon.

¹Maxime Pineau,²Maximilien Mathian,^1,3Fabien Baron,¹Benjamin Rondeau,¹Laetitia Le Deit,²Thierry Allard,¹Nicolas Mangold
American Mineralogist 107, 1453-1469 Open Access Link to Article [http://www.minsocam.org/msa/ammin/toc/2022/open_access/AM107P1453.pdf]
¹Laboratoire de Planétologie et Géodynamique, UMR CNRS 6112, Université de Nantes, Université d’Angers, Nantes, France
²Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, UMR CNRS 7590, Sorbonne Université, Paris, France
³Institut de Chimie des Milieux et Matériaux de Poitiers, UMR CNRS 7285, Université de Poitiers, Poitiers, France
Copyright: The Mineralogical Society of America

Kaolinite is an Al-rich phyllosilicate commonly observed on Earth as a product of the chemical
weathering of aluminosilicates. It has also been detected on the martian surface by orbital remote
sensing observations. While the determination of the geological processes of formation of terrestrial
kaolinite (i.e., hydrothermal activity, continental surface weathering, diagenesis) involves the coupling of field observation and multiple laboratory measurements, only geomorphology and associated
minerals are generally available to determine their geological origin on Mars. Kaolinite crystallinity
depends on many physicochemical parameters reflecting its conditions of crystallization. To determine if the near-infrared (NIR) spectral signature of kaolinite enables estimation of its crystallinity
and furthermore if this method can be used to identify the geological processes involved in kaolinite
formation, we carried out an in-depth analysis of NIR spectra of reference terrestrial kaolinites that
formed in various geological contexts. We calculated second and third derivatives for each spectrum
to highlight subtle variations in the spectral properties of kaolinite. This allowed the identification of
27 spectral contributions for the 4500 and 7000 cm−1 Al-OH-related regions of absorption bands. The
position shifts and shape variations of these spectral contributions were intimately linked to variations
of crystallinity, which was qualitatively estimated using Hinckley and Liétard XRD (dis)order indices.
The results obtained show that the NIR signature of kaolinite is influenced by the stacking disorder of
layers that has some influence on the vibrations of the interfoliar and inner Al-OH groups. Our study
also confirms that: (1) well-ordered kaolinites are not restricted to hydrothermal deposits; (2) kaolinites
from a similar sedimentary or pedogenetic context often display contrasting degrees of crystalline
order; and (3) poorly ordered kaolinites are more likely to have a sedimentary or pedogenetic origin.
Finally, this work highlights that obtaining spectra with sufficient spectral resolution could help to
estimate the crystallinity of kaolinite and, in the best cases, its geological origin, both on Earth and
Mars, especially with in situ NIR measurements.