^1,2Naoki HIRAKAWA,²Yoko KEBUKAWA,³Takazo SHIBUYA,^3,4Hisahiro UEDA,¹Kensei KOBAYASHI
Journal of Mineralogical and Petrological Sciences 118 (in Press) Link to Article [DOI https://doi.org/10.2465/jmps.220913]
¹Department of Education, Osaka Kyoiku University
²Graduate School of Engineering Science, Yokohama National University
³SUGAR Program, X-star, Japan Agency for Marine-Earth Science and Technology (JAMSTEC)
⁴Department of Chemistry, Faculty of Science, Gakushuin University

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¹Maggie A. Thompson,²Myriam Telus,³Graham Harper Edwards,⁴Laura Schaefer,²Jasmeet Dhaliwal,⁵Brian Dreyer,¹Jonathan J. Fortney,⁶Kyle Kim
The Planetary Science Journal 4, 10 Open Access Link to Article [DOI 10.3847/PSJ/acf760]
¹Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064, USA
²Department of Earth and Planetary Sciences, University of California, Santa Cruz, CA 95064, USA
³Department of Earth Sciences, Dartmouth College, Hanover, NH 03755, USA
⁴Geological Sciences, School of Earth, Energy, and Environmental Sciences, Stanford University, Stanford, CA 94305, USA
⁵Institute of Marine Science, University of California, Santa Cruz, CA 95064, USA
⁶Department of Geology, University of Maryland, College Park, MD 20742, USA

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¹Dian Ji,¹Nicholas Dygert
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2023.11.004]
¹Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN 37996, United States of America
Copyright Elsevier

Apatite, as an accessory phase in igneous and metamorphic rocks, has important petrological significance due to its capacity to accommodate appreciable amounts of many trace elements in its mineral structure. To better constrain trace element partitioning between apatite and silicate melts, we conducted experiments that produced apatites approaching fluorapatite (FlAp), hydroxylapatite (OHAp) and chlorapatite (ClAp) endmembers separately at 1050 and 1100 °C, 1 GPa pressure, under oxygen fugacity (fO₂) about one log unit below iron-wüstite buffer to four log unit above fayalite-magnetite-quartz buffer. We report the results of 12 experiments which demonstrate that ClAp exhibits lower trace element partition coefficients compared with FlAp and OHAp, especially for Rare Earth Elements (REEs) under all run conditions explored, suggesting trace element partitioning is sensitive to anion site occupancy. Divalent cations are less sensitive to anion occupancy. Positive Eu partitioning anomalies (DEu/DEu*, where Eu is the chondrite normalized abundance and Eu* is the interpolated value from neighboring elements ordered by atomic number) are observed in ClAp experiments under the relatively low fO₂, whereas negative Eu anomalies are exhibited by FlAp and OHAp under the same fO₂ conditions. We infer that anionic occupancies have a direct impact on the substitution mechanisms of trace elements in apatite, thereby influencing their partition coefficients. Beyond the anions, correlations of apatite compositional components (�Ca, �Na, �� and �Si) with partition coefficients suggest they exert crystal chemical controls on trace element partitioning. Based on these observations, we developed parameterized lattice strain models to predict the partitioning of divalent and trivalent elements as a function of temperature and apatite composition, and an fO₂-dependent apatite-melt Eu partitioning model and oxybarometer. We further developed a Eu in apatite-plagioclase oxybarometer that enables us to calculate the fO₂ of apatite and plagioclase-bearing magmatic and subsolidus systems, and evaluated the influence of subsolidus reequilibration on the new oxybarometer. Applied to one of our experiments, winonaite HaH193, and samples from Sept-Iles layered intrusion, the oxybarometer recovers their anticipated fO₂s, ranging from about two log units below the iron-wüstite buffer to the fayalite-magnetite-quartz buffer. Using the new REE and fO₂-dependent Eu partitioning models, we constrained the petrogenesis of lunar KREEP basalt and estimated the relative volatile content in the late lunar magma ocean (LMO) cumulates. The model suggests a relative depletion of Cl in the LMO cumulates, consistent with Cl isotopic analyses and volatile abundance measurements in previous work, suggesting that differential loss of volatiles occurred before or during the late-stage evolution of the LMO.

¹Emily M. Chiappe,¹Richard D. Ash,²Arto Luttinen,³Sari Lukkari,³Jukka Kuva,⁴Connor D. Hilton,¹Richard J. Walker
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14095]
¹Department of Geology, University of Maryland, College Park, Maryland, USA
²Finnish Museum of Natural History, University of Helsinki, Helsinki, Finland
³Geological Survey of Finland, Espoo, Finland
⁴Pacific Northwest National Laboratory, Richland, Washington, USA
Published by arrangement with John Wiley & Sons

The meteorite Lieksa was found in 2017 in Löpönvaara, Finland, and later donated to the Finnish Museum of Natural History. Here, we report siderophile element concentrations, genetic isotopic data, and a metal–silicate segregation age for the meteorite. The ~280 g Lieksa is ~80% metal and ~20% silicate and oxide inclusions by volume, with the inclusions consisting primarily of Fe-rich olivine. Due to Lieksa’s silicate content, coupled with a texture characterized by metal enclosing the silicates, it has been classified as a pallasite. Lieksa’s olivine and bulk chemical characteristics are distinct from those of the known pallasite and iron meteorite groups, consistent with its classification as ungrouped. The meteorite exhibits a flat, chondrite-normalized highly siderophile element pattern, consistent with an origin as an early crystallization product from a metallic melt with chondritic relative abundances. Molybdenum, Ru, and 183W isotopic data indicate that Lieksa formed in the non-carbonaceous (NC) domain of the solar nebula. Radiogenic 182W abundances for Lieksa yield a model metal–silicate segregation age of 1.5 ± 0.8 Myr after calcium-aluminum-rich inclusion formation, which is within the range established for other NC-type pallasite and iron meteorite parent bodies.

¹Su, Bin,^1,3Zhang, Di,^1,3Chen, Yi,²Yang, Wei¹Mao, Qian,¹Li, Xian-Hua,¹Wu, Fu-Yuan
Science Advances 68, 1918-1927 Link to Article [DOI 10.1016/j.scib.2023.07.020]
¹State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China
²Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China
³College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China

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¹Ji, Jie,¹Liu, Yafang,¹Yang, Xu,²Zhang, Weiwei,³Xiao, Tao,⁴Sun, Jing,²Jiang, Shengyuan
Advances in Space Research 72, 3357-3375 Link to Article [DOI 10.1016/j.asr.2023.05.021]
¹Beijing Institute of Spacecraft System Engineering, Beijing, 100094, China
²State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin, 150001, China
³Institute of Remote Sensing Satellite, China Academy of Space Technology, Beijing, 100094, China
⁴China Satellite Communications Co. Ltd, Beijing, 100190, China

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^1,2Venkateswara Rao Manga,^1,2Thomas J. Zega
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2023.11.001]
¹Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ
²Department of Materials Science and Engineering, University of Arizona, Tucson, AZ
Copyright Elsevier

Ultrarefractory (UR) condensates found in refractory inclusions in chondrites contain records of the early nebular thermochemistry that prevailed in the high-temperature region close to the protosun. Recent reports of the UR phases such as allendeite (Sc4Zr3O12), tazheranite ((Zr,Ti,Ca)O2-x), and kangite ((Sc,Ti,Al,Zr,Mg,Ca,□)2O3) imply, respectively, nebular condensation temperatures and origins higher than and inward of those previously deduced from calcium-aluminum-rich inclusions. However, knowledge gaps on their thermochemistry have precluded a quantitative understanding of temperatures and chemical pathways that led to their origins in the early solar protoplanetary disk. Here we use density functional theory to determine the thermochemistry of these materials for the first time. We find that allendeite is a stable phase under equilibrium conditions with its condensation temperature (1643 K at 10-4 bar) in the same range as that of nominal hibonite (CaAl12O19, 1637 K at 10-4 bar). Among the UR oxides, tetragonal ZrO2 exhibits the highest condensation temperature (1739 K at 10-4 bar) and potentially reveals the high-temperature limits at which solid dust could have survived in the inner region of the disk. In comparison, we find that pure cubic ZrO2 does not form from a cooling gas of solar composition undergoing equilibrium condensation. Similarly, we find that the stoichiometric endmember of kangite, Sc2O3 does not condense under equilibrium conditions, and moreover, the role of Ti and Zr as solutes is crucial to modeling its stability and origins.

¹A. Pommier,^1,2M.J. Tauber,^1,3H. Pirotte,¹G.D. Cody,¹A. Steele,¹E.S. Bullock,³B. Charlier,¹B.O. Mysen
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2023.10.027]
¹Carnegie Institution for Science, Earth and Planets Laboratory, Washington, DC 20015, USA
²University of California San Diego, Department of Chemistry and Biochemistry, La Jolla, CA 92093, USA
³University of Liège, Department of Geology, Sart Tilman, Belgium
Copyright Elsevier

Elucidating the role of sulfur on the structure of silicate glasses and melts at elevated pressures and temperatures is important for understanding transport properties, such as electrical conductivity and viscosity, of magma oceans and mantle-derived melts. These properties are fundamental for modeling the evolution of terrestrial planets and moons. Despite several investigations of sulfur speciation in glasses, questions remain regarding the effect of S on complex glasses at highly reducing conditions relevant to Mercury. Glasses were synthetized with compositions representative of the Northern Volcanic Plains of Mercury and containing quantities of S up to 5 wt.%. Multiple spectroscopic methods and microprobe analyses were employed to probe the glasses, including in situ impedance spectroscopy at 2- and 4-GPa pressures and temperatures up to 1740 K using a multi-anvil press, 29Si NMR spectroscopy, and Raman spectroscopy. Electrical activation energies (Ea) in the glassy state range from 0.56 to 1.10 eV, in agreement with sodium as the main charge carrier. The electrical measurements indicate that sulfide improves Na+ transport and may overcome a known impeding effect of the divalent cation Ca2+. The glass transition temperature lies between 700-750 K, and for temperatures up to 970 K Ea decreases (0.35-0.68 eV) and the conductivities of the samples converge (∼5-8 ×10-3 S/m). At Tquench, the melt fraction is 50-70% and melt conductivity varies from 0.7 to 2.2 S/m, with the sample containing 5 wt.% S the most conductive among the set. 29Si NMR spectra reveal that a high fraction of S bonds with Si in these complex glasses, a characteristic that has not been recognized previously. Raman spectra and maps reveal regions rich in Ca-S or Mg-S bonds. The evidence of sulfide interactions with both Si and Ca/Mg suggest that alkaline earth sulfides can be considered weak network modifiers in these glasses, under highly reduced conditions.

¹Tarryn Aucamp,¹Geoffrey H. Howarth,¹Chad J. Peel,²Gelu Costin,³James M. D. Day,¹Petrus le Roux,⁴James M. Scott,⁵Ansgar Greshake,⁶Rainer Bartoschewitz
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14090]
¹Department of Geological Sciences, University of Cape Town, Rondebosch, South Africa
²Department of Earth, Environmental and Planetary Sciences, Rice University, Houston, Texas, USA
³Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, USA
⁴Department of Geology, University of Otago, Dunedin, New Zealand
⁵Institut für Mineralogie, Museum für Naturkunde, Humboldt-Universität zu Berlin, Berlin, Germany
⁶Bartoschewitz Meteorite Laboratory, Gifhorn, Germany
Published by arrangement with John Wiley & Sons

The Dar al Gani (DaG) olivine-phyric shergottites share mineralogical and geochemical characteristics, which confirm that these meteorites are derived from a single source. Bulk trace elements (La/Yb—0.12), in situ maskelynite 87Sr/86Sr (~0.7014) and redox estimates (FMQ ~ −2) indicate derivation from a depleted, reduced mantle reservoir; identical to all ~470 Ma shergottites ejected at 1.1 Ma. The DaG shergottites have been variably affected by terrestrial alteration, which precipitated carbonate along fractures and modified bulk-rock fluid mobile (e.g., Ba) elements. Nonetheless, sufficient data are available to construct a multi-stage formation model for the DaG shergottites and other 1.1 Ma ejection-paired shergottites that erupted at ~470 Ma. First, partial melting of a depleted mantle source occurred at 1540 ± 20°C and 1.2 ± 0.1 GPa, equivalent to > ~100 km depth. Then, initial crystallization in a staging chamber at ~85 km depth at the crust–mantle boundary took place, followed by magma evolution and variable incorporation of antecrystic olivine ± orthopyroxene. Subsequently, crystallization of olivine phenocrysts and re-equilibration of olivine antecrysts occurred within an ascending magma. Finally, magmas with variable crystal loads erupted at the surface, where varied cooling rates produced a range of groundmass textures. This model is similar to picritic flood basalt magmas erupted on Earth.

^1,2Qian Yuan et al. (>10)
Nature 623, 95-99 Link to Article [DOI https://doi.org/10.1038/s41586-023-06589-1]
¹School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
²Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA

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