^1,2Hamed Pourkhorsandi,¹Jérôme Gattacceca,¹Pierre Rochette,³Thomas Smith,⁴Lydie Bonal,⁵Massimo D’Orazio,¹Bertrand Devouard,¹Corinne Sonzogni,²Vinciane Debaille
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13801]
¹CNRS, IRD, INRAE, CEREGE, Aix-Marseille Univ, Aix-en-Provence, France
²Laboratoire G-Time, Université Libre de Bruxelles, CP 160/02, 50, Av. F.D. Roosevelt, Brussels, 1050 Belgium
³Institute of Geology and Geophysics, Chinese Academy of Sciences, 19 Beitucheng Western Road Chaoyang District, Box 9825, Beijing, 100029 China
⁴Institut de Planétologie et d’Astrophysique de Grenoble, Grenoble, France
⁵Dipartimento di Scienze della Terra, Università di Pisa, Pisa, Italy
Published by arrangement with John Wiley & Sons

The Famenin meteorite fell around 08:30 a.m. local time (GMT+4.5) on June 27, 2015 on the roof of a house in Famenin, a town in NW Iran. A single 640 g stone was recovered, shattered into several pieces upon impact. The shape of the impact hole and the relative position of the recovered meteorites indicate a N-NW fall direction. Famenin is an ordinary chondrite (OC) with well-preserved chondrules of various types, (Fe,Ni) metal, troilite, phosphate, and chromite. The organic matter systematics and the olivine and low-Ca compositional distributions (percent mean deviations 18% and 31%, respectively) indicate it is a type 3.4/3.8 chondrite. Considering the average chemical compositions of olivine (Fa17.5±4.7) and low-Ca pyroxene (Fs16.8±7.5), average Co content of the kamacite (5.6 mg g−1), and Cu/Ni and Ga/Ni ratios, Famenin should be classified as an H chondrite. However, saturation magnetization is 26.0 Am2 kg−1, indicating a bulk metal content similar to L chondrites. Similarly, the whole-rock Ni and Co contents (13073 and 540 µg g−1, respectively), and average chondrule diameter (550 µm) are closer to typical values for L chondrites than H chondrites. The (Fe,Ni) metal modal abundance (5 vol%), magnetic susceptibility, and possibly whole-rock oxygen isotopic composition indicate intermediate properties between H and L chondrites. Noble gas composition and cosmic-ray exposure ages of Famenin and El Médano 195 (another intermediate OC) shows their gas-rich character and an older ejection age from their parent body than those for the majority of H and L chondrites. Famenin, together with similar intermediate OCs, increases the diversity of this meteorite clan and suggests the existence of a separate OC group with a composition broadly intermediate between H and L groups for which a different designation (HL) is proposed. OCs likely originate from more than three parent bodies (H, L, and LL) as traditionally proposed.

¹Robert W. Nicklas,¹James M. D. Day,²Zoltan Vaci,³Arya Udry
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13805]
¹Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, 92093 USA
²Department of Earth and Planetary Science, Institute of Meteoritics, University of New Mexico, Albuquerque, New Mexico, 87131 USA
³Department of Geoscience, University of Nevada, Las Vegas, Las Vegas, Nevada, 89154 USA
Published by arrangement with John Wiley & Sons

Northwest Africa (NWA) 8686 is an olivine-phyric shergottite containing up to ~500 μm long olivine crystals in a fine-grained groundmass of augite, pigeonite, and maskelynite, with accessory merrillite, pyrrhotite, and oxides. Bulk rock and mineral major and trace element concentrations are reported for NWA 8686, along with bulk rock highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd, Re) abundances and 187Re-187Os data. Based on its mineralogy, texture, and bulk rock rare earth element (REE) abundances, NWA 8686 is classified as an intermediate olivine-phyric shergottite. It is notable for having some of the most ferroan olivine macrocrysts (forsterite content = 51.5 ± 3.5) of any olivine-phyric shergottite. Olivine is absent from the NWA 8686 groundmass, which is unique for olivine-phyric shergottites, and the calculated groundmass composition is also not olivine normative. The bulk meteorite has a low Mg# of 59 yet has HSE in broadly chondritic proportions (~0.005 × CI chondrite). The bulk rock REE pattern for NWA 8686 shows depletions in both the light and heavy REE relative to the middle REE. Compiled olivine and bulk rock data for olivine-phyric shergottites indicate that olivine macrocrysts in almost all these meteorites are the result of entrainment of antecrysts or xenocrysts. The combination of low Mg# and chondritic HSE signatures in NWA 8686 means that it may have been formed either from the mixing between an evolved lava and early-formed HSE-rich phases such as Os-Ir alloys or by the melting of a low Mg# mantle source with chondritic HSE abundances. The elevated Gd/Yb ratio in both NWA 8686 and other intermediate olivine-phyric shergottites indicates that garnet was involved as either a residual or fractionating phase in their petrogenesis.

¹Marina Martínez,¹Adrian J.Brearley
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2022.03.019]
¹Department of Earth & Planetary Sciences, MSC03-2040, 1University of New Mexico, Albuquerque, NM 87131, USA
Copyright Elsevier

Queen Alexandra Range (QUE) 99177 is one of the least altered CR carbonaceous chondrite known, with mineralogical and isotopic characteristics that indicate a high level of pristinity. In this study, we have examined the so-called smooth rims that surround many type I chondrules in QUE 99177, using SEM, EPMA, and FIB-TEM techniques. We have characterized their constituent phases to unravel the precursor material(s) of smooth rims, assess their formation mechanisms, and constrain the conditions of the altering fluid. Smooth rims are the most common type of rims around type I chondrules and exclusively occur around chondrules with Silica-rich Igneous Rims (SIRs). Smooth rims consist of an Fe-rich, hydrous silicate material that is Si- and Fe-rich, with minor Mg, Al, Ca, and Mn, and gives low analytical totals measured by EPMA. TEM observations reveal that the Fe-rich silicate phase is an amorphous gel that contains unaltered crystalline phases and igneous glass. Crystalline phases consist of igneous, unaltered, zoned pyroxenes with compositions consistent with pyroxenes in SIRs, as well as albite and chromite. The amorphous gel preserves previous crystal outlines with morphologies consistent with silica (cristobalite) grains in SIRs and has a composition identical to pseudomorphic silica replacements in SIRs. Based on these observations, we conclude that smooth rims derive from low-temperature aqueous alteration of silica in SIRs by an Fe-rich fluid. We suggest that the Fe was derived by leaching of amorphous silicates in the matrix, which reacted rapidly with melted water ice, although alteration of Fe,Ni metal blebs in SIRs could potentially be an additional source of Fe. Silica underwent dissolution and replacement whereas feldspar and glass remained unaltered because (1) the fluid was slightly alkaline, (2) cristobalite has a reaction rate much higher than quartz and feldspar, and (3) the alteration was very limited and fast, indicating that it was due solely to melting of accreted water ice and there was no introduction of additional fluid from external sources.

¹Nabawy, B.S.
Natural Resources Research 31, 179-189 Open Access Link to Article [DOI 10.1007/s11053-021-10007-6]
¹Department of Geophysical Sciences, National Research Centre, 33 ElBohouth street, P.O. 12311, Dokki, Cairo, Egypt

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

^1,2Ishiguro M. et al. (>10)
Monthly Notices of the Royal Astronomical Society 509, 4128-4142 Link to Article [DOI 10.1093/mnras/stab3198]
¹Department of Physics and Astronomy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, South Korea
²Snu Astronomy Research Center, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, South Korea

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

¹Ming Jin,¹Xiaozhong Ding,¹Hunying Han,¹Jianfeng Pang,^1,2Ying Wang
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2022.115008]
¹Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China
²Graduate School of Chinese Academy of Geological Sciences, Beijing 100037, China
Copyright Elsevier

Mineral abundance quantification of lunar surface materials using remotely acquired spectra can be achieved with spectral unmixing methods, but this has remained a challenging problem. The existing unmixing methods neglect the existence of widespread glass material and the spectral similarity of different minerals. To solve this problem, this study proposes a method to calculate the main mineral abundances in lunar regolith based on reflectance spectra by utilizing Fisher transformation combined with multiple endmember spectral mixture analysis (MESMA). A set of spectra of lunar main constituents, including plagioclase, pyroxene, ilmenite, olivine and glass material, were selected from the RELAB spectral database and used as endmembers. The endmember spectra were utilized to compute the projection vectors, with which the spectral characteristics can be transformed into low-dimensional Fisher space in which intraclass spectral variability can be minimized while the interclass variability of different mineral spectra can be maximized. The endmember spectra and the lunar soil spectra in the Lunar Soil Characterization Consortium (LSCC) dataset were both transformed into Fisher space, in which MESMA was executed to acquire the fraction of each endmember. MESMA allows for comprehensive endmember expressions by representing a type of mineral using multiple spectra rather than a single endmember. Compared with laboratory mineral measurements, this approach estimated the mineral abundances with determination coefficient R2 values equal to 0.88 and 0.65 in the lunar mare and highland regions, respectively. After validation with laboratory data, the method was further applied at the regional scale where Apollo 12 and Apollo 16 landed by using M3 images, and the estimated accuracy of different minerals was similar to that of the laboratory spectra.

^1,2,3Zélia Dionnet et al. (>10)
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.13807]
¹Institut d’Astrophysique Spatiale, CNRS, Université Paris-Saclay, Orsay, 91405 France
²Dip. Di Scienze Applicate, Università di Napoli Parthenope, Centro Direzionale di Napoli, Isola C4, Naples, 80143 Italy
³Istituto di Astrofisica e Planetologia Spaziali—INAF, Rome, Italy
Published by arrangement with John Wiley & Sons

In this paper, we report the results of a campaign of measurements on four fragments of the CM Aguas Zarcas (AZ) meteorite, combining X-ray computed tomography analysis and Fourier-transform infrared (FT-IR) spectroscopy. We estimated a petrologic type for our sampled CM lithology using the two independent techniques, and obtained a type CM2.5, in agreement with previous estimations. By comparing the Si-O 10-µm signature of the AZ average FT-IR spectra with other well-studied CMs, we place AZ in the context of aqueous alteration of CM parent bodies. Morphological characterization reveals that AZ has heterogeneous distribution of pores and a global porosity of 4.5 ± 0.5 vol%. We show that chondrules have a porosity of 6.3 ± 1 vol%. This larger porosity could be inherited due to various processes such as temperature variation during the chondrule formation and shocks or dissolution during aqueous alteration. Finally, we observed a correlation between 3D distributions of organic matter and mineral at micrometric scales, revealing a link between the abundance of organic matter and the presence of hydrated minerals. This supports the idea that aqueous alteration in AZ’s parent body played a major role in the evolution of the organic matter.

¹C.M.Lisse,^2.3J.K.Steckloff
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2022.114995]
¹Space Exploration Sector, Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Rd, Laurel, MD, USA 20723
²Planetary Science Institute, Tucson, AZ 85719, USA
³Department of Aerospace Engineering and Engineering Mechanics, University of Texas at Austin, Austin, TX 78712, USA
Copyright Elsevier

In 2010 Jewitt and Li published a paper examining the behavior of “comet-asteroid transition object” 3200 Phaethon, arguing it was asteroid-like in its behavior throughout most of its orbit, but that near its perihelion, at a distance of only 0.165 AU from the sun, its dayside temperatures would be hot enough to vaporize rock (>1000 K, Hanus et al., 2016). Thus it would act like a “rock comet” as gases produced from evaporating rock were released from the body, in a manner similar to the more familiar sublimation of water ice into vacuum seen for comets coming within ~3 AU of the Sun. In this Note we predict that the same thermal effects that would create “rock comet” behavior with Qgas ~ 1022 mol/s at perihelion would also help bluen the surface via preferential thermal alteration and sublimative removal of surface Fe and refractory organics, known reddening and darkening agents. These predictions are testable by surveying other objects on Phaethon-like small perihelion orbits, and by in situ measurements from the upcoming DESTINY+ mission to Phaethon by JAXA.

¹Amanda C. Stadermann,²Bradley L. Jolliff,²Michael J. Krawczynski,¹Christopher W. Hamilton,¹Jessica J. Barnes
Meteoritics & Planetary Sciences (in Press) Link to Article [https://doi.org/10.1111/maps.13795]
¹Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Blvd, Tucson, Arizona, 85721 USA
²Department of Earth and Planetary Sciences & McDonnell Center for Space Sciences, Washington University in St. Louis, 1 Brookings Dr, St. Louis, Missouri, 63130 USA
Published by arrangement with John Wiley & Sons

Sample 12032,366-18 is a 41.2 mg basaltic rock fragment collected during the Apollo 12 mission to the Moon. It is enriched in incompatible trace elements (e.g., 7 ppm Th), but does not have a bulk composition that would be considered a KREEP (enriched in potassium, rare earth elements, and phosphorous) basalt. The sample is of particular interest because it may be representative of some of the mare basalts within Oceanus Procellarum that are inferred to be Th-rich, based on remote sensing data. The major mineral assemblage of 12032,366-18 is pyroxene, plagioclase, olivine, and ilmenite, and the bulk composition has 4.2 wt% TiO2, 11.7 wt% Al2O3, and 0.25 wt% K2O. The sample contains regions of late-stage crystallized minerals and glass (collectively termed mesostasis), including K-feldspar, apatite, rare earth (RE) merrillite, ilmenite, troilite, silica, and relatively sodic plagioclase adjacent to ferroan pyroxene. The mesostasis also occurs in several areas that are highly enriched in silica and intergrown with K-feldspar and very fine-grained, high-mean-atomic-number phases. We explore the petrology of this sample, including the origin of the Si-K-rich mesostasis to assess whether the mesostasis had formed by silicate liquid immiscibility (SLI). We used experiments to determine if the bulk composition of 12032,366-18 is representative of a bulk liquid composition, how the residual liquid evolves, and to investigate the partitioning of elements between phases as the melt evolves. Experiments support that the mesostasis formed by SLI after crystallization of minerals closely matches the major-mineral assemblage of 12032,366-18. Experiments bracket the onset of SLI and merrillite saturation between 1024 and 1002 °C. Some high field strength elements, such as Zr and P, partition preferentially into the Fe-rich liquid. From the experiments, we infer that the bulk composition of 12032,366-18 represents the magma from which it crystallized. Based on the Th-rich and KREEP-bearing chemistry of this sample, along with experimental evidence showing that the sample is representative of a bulk liquid composition and not a cumulate, we conclude that basalt fragment 12032,366-18 was delivered to the Apollo 12 landing site as ejecta from a distant impact and could represent an Oceanus Procellarum basalt. Missions to Oceanus Procellarum, such as Chang’E 5, have the potential to confirm whether some of those basalts are indeed enriched in Th and other incompatible trace elements as indicated by remote sensing.

¹Jie-Jun Jing,²Yanhao Lin,³Jurrien S.Knibbe,¹Wim van Westrenen
Earth and Planetary Science Letters 584, 117491 Link to Article [https://doi.org/10.1016/j.epsl.2022.117491]
¹Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, the Netherlands
²Center for High Pressure Science and Technology Advanced Research, Beijing, 100094, People’s Republic of China
³Royal Observatory of Belgium, Ringlaan 3, 1180 Ukkel, Belgium
Copyright Elsevier

High-pressure, high-temperature experiments have been conducted at deep lunar mantle conditions to constrain the garnet stability field. Using the Taylor Whole Moon composition, garnet is found to be stable at pressures above 3 GPa and temperatures below 1700 °C, yielding a smaller stability field than previously suggested on the basis of thermodynamic calculations. Experimental data are used to model equilibrium crystallization in a ‘two-stage’ model of lunar magma ocean (LMO) crystallization starting from a fully molten Moon. In the first stage, isothermal (1600 °C) equilibrium crystallization of the LMO would produce garnet-bearing lherzolite cumulates (containing up to ∼20 wt.% garnet) in the lowermost lunar mantle. Garnet in the deep lunar mantle would significantly decrease the Al2O3 content of the residual LMO and impact HREE/MREE fractionation. Numerical modeling of the second stage (residual LMO fractional crystallization) shows a delay in plagioclase saturation compared to models of single-stage fractional crystallization of a whole-Moon LMO of the Taylor Whole Moon composition, thinning the anorthositic crust from 95 km to 75 km. To reach the upper limit of current estimates of the average lunar crustal thickness (∼45 km), the two-stage scenario needs to be accompanied by a total of 10% liquid trapped in cumulates and 70% efficiency of plagioclase flotation. We also conduct trace element evolution modeling and reproduce a REE pattern identical to high K, REE, and P (KREEP) compositions after 99.8% solidification, when starting with a CI chondritic REE abundance. The density of a garnet-bearing deep lunar mantle is significantly higher than the density of olivine/orthopyroxene mixtures without garnet. The present-day lowest mantle in the Moon could therefore be characterized by chemical interactions between the earliest (garnet-bearing) and latest (ilmenite-bearing) products of LMO crystallization.