^1,2Amanda Ostwald,¹Arya Udry,³James M. D. Day,^4,5,6,7Juliane Gross
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14159]
¹Department of Geoscience, University of Nevada, Las Vegas, Las Vegas, Nevada, USA
²Smithsonian National Museum of Natural History, Washington, DC, USA
³Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, USA
⁴NASA Johnson Space Center, Houston, Texas, USA
⁵Department of Earth and Planetary Science, Rutgers University, Piscataway, New Jersey, USA
⁶Lunar and Planetary Institute, Houston, Texas, USA
⁷Department of Earth and Planetary Sciences, The American Museum of Natural History, New York, New York, USA
Published by arrangement with John Wiley & Sons

Nakhlite and chassignite meteorites are cumulate rocks thought to originate from the same location on Mars. Petrogenetic relationships between nakhlites and chassignites are not fully constrained, and the two cumulus phases in nakhlites—olivine and clinopyroxene—possibly formed either together from one magma or separately from different magmas. Primary magma compositions can potentially be determined from studies of melt inclusions (MIs) trapped within early-formed mineral phases. MIs frequently undergo post-entrapment effects, and when such processes occur, there can be significant changes to their compositions. Here, we report major, minor, and trace element abundances for MIs in cumulus phases in nakhlites and chassignites. The melt compositions that they record are variable (MgO = 2.50–13.5 wt%, K2O = 0.03–3.03 wt%, La/Yb = 2.46%–16.4%) and are likely affected by diffusive reequilibration with changing magma composition outside of their host phases. Evidence for diffusive reequilibration suggests that nakhlite and chassignite magmas were generated in an open system, and cumulus phases may have undergone magma storage and mixing. Such processes may be akin to those that occur in terrestrial intrusive magmatic systems by open-system magma recharge. MIs within the nakhlite and chassignite suite therefore provide insights into magmatic processes during magma storage and transit on Mars.

¹Mendy M. Ouzillou,²Christopher D. K. Herd
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14160]
¹SkyFall Meteorites, Bastrop, Texas, USA
²Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada
Published by arrangement with John Wiley & Sons

The use of meteoritic iron in the manufacture of human artifacts since the Bronze Age has been well documented, including the iron blade of Tutankhamun’s dagger. Whereas the preservation of textures and mineral inclusions suggest relatively low temperature (<950°C) working of meteoritic metal used in artifacts, higher temperature working—that is, forging—could have occurred, based on studies of Bronze Age slag. The extent to which the forging of meteoritic iron might change the bulk composition, especially the trace elements used for classification of iron meteorites, is largely unknown. Using electron microbeam methods (SEM and EPMA), and trace element analysis (ICP-MS), we analyze metal obtained at different stages during the modern forging of a set of knife blades from fragments of the Gebel Kamil meteorite, and assess the degree to which bulk element composition, mineral inclusions, and textures are modified. We find that while forging does destroy the original texture and removes mineral inclusions, it does not significantly modify the trace elements typically used in iron meteorite classification, at least for the relatively Ni-rich composition represented by Gebel Kamil. While we acknowledge that the modern method by which the knife blades were forged from Gebel Kamil would not have occurred in the Bronze Age, our results represent an upper temperature limit relative to the inferred conditions used in ancient forging. The identification of the meteorite (if still in existence) that was used for artifacts is feasible, based on our results and current literature on ancient meteoritic artifacts.

¹Debjeet Pathak,¹Rajdeep Dasgupta
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2024.02.012]
¹Department of Earth, Environmental and Planetary Sciences, Rice University, 6100 Main Street, MS 126, Houston, TX 77005, USA
Copyright Elsevier

Delivery of nitrogen (N), one of the most important elements for life, to Earth thought to have occurred via both undifferentiated and differentiated bodies, lasting at least 50-100 Ma from the birth of the Solar System. Therefore, to understand how Earth got its N, it is imperative to know the N budget of the earliest formed bodies in our Solar System. The best astromaterials available for providing constraints on N budget of the earliest formed planetesimals are the iron meteorites. However, iron meteorites are crystallized products of a liquid alloy and do not represent the N budget of the bulk cores of various iron meteorite parent bodies (IMPBs). Therefore, to determine how N partitioned between solid alloy (sa) and liquid alloy (la) (�Nsa/la) during crystallization of molten metal alloy core, we present a series of equilibrium partitioning experiments at 1-2 GPa and 1150-1550 ℃ for various initial starting compositions having different sulfur (S), nickel (Ni), iron (Fe) and fixed nitrogen (N) concentrations. We observe that N changes from mildly incompatible to mildly compatible with increasing S concentration in the liquid alloy. Furthermore, we observed that N concentration in solid alloy decreases with increasing temperature, while pressure and Ni content showed almost no effect on the partitioning behavior of N. We used a regression model based on the results of our study and a previous study to establish a parameterization for �Nsa/la. Using our parameterized �Nsa/la, we determine potential siderophile element proxies of N in metallic systems and model the initial N budget of various IMPBs groups pertaining to the inner (Non-Carbonaceous (NC) reservoir) and outer Solar System (Carbonaceous (CC) reservoir). Between two possible end-member styles of IMPB differentiation (IMO – Internal Magma Ocean; EMO – External Magma Ocean), EMOs result in a higher initial N budget with a major fraction getting lost via atmospheric loss. Importantly, our calculations suggest a gradation in the N budget of CC and NC IMPBs with CC IMPBs hosting lesser N than NC IMPBs. Therefore, the early Solar protoplanetary disk likely showed a gradation in N both in its elemental and isotopic composition.

¹Anicia Arredondo,²Margaret M. McAdam,¹Tracy M. Becker,³Linda Elkins-Tanton,⁴Zoe Landsman,⁵Thomas Müller
The Planetary Science Journal 5, 33 Open Access Link to Article [DOI 10.3847/PSJ/ad16ec]
¹Southwest Research Institute, San Antonio, TX 78238, USA
²NASA Ames Research Center, Moffat Field, CA 94035, USA
³Arizona State University, Tempe, AZ 85281, USA
⁴University of Central Florida, Orlando, FL 32826, USA
⁵Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, D-85748, Germany

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

¹Jeremy W. Boyce,¹Francis M. McCubbin,¹Nicole Lunning,^1,2Tyler Anderson
The Planetary Science Journal 5, 53 Open Access Link to Article [DOI 10.3847/PSJ/ad1830]
¹Astromaterials Research and Exploration Science Division, NASA Lyndon B. Johnson Space Center, 2101 E. NASA Parkway, Houston, TX 77058, USA; jeremy.w.boyce@nasa.gov
²Now at Lawrence Livermore National Laboratories, Livermore, CA 94550, USA

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

¹Andrea Patzer,¹Julia Kowalski,¹Tommaso Di Rocco,¹Andreas Pack
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14155]
¹Geosciences Centre of the University of Göttingen, Göttingen, Germany
Published by arrangement with John Wiley & Sons

The ureilite parent body (UPB) was, in all likelihood, completely broken apart when hit by another object early in its history and reassembled into daughter bodies. We here present a study tailored to constrain the dimensions of the impact debris produced in the catastrophic disruption. Using a customized Python code to simulate the thermal evolution of the UPB fragments, we compared the FeO profiles modeled for different depths within those fragments with those measured across the reduction rims in olivines of 12 different ureilites (n = 37). Our profile data were fitted to the theoretical cooling profiles determined with a transient thermal model. The results are coherent and consistent with earlier studies and, despite using simplified boundary conditions (fragments described as ideal spheres and maximum radiation), our data provide valuable context on possible cooling pathways of the UPB debris. In detail, we found that the average depths within the given fragments from which our samples of ureilites originated were limited to 0.3–0.4 ± 0.1 m, with only few exceptions (e.g., one highly reduced sample lacked suitable reduction profiles suggesting either a depth of origin of >2 m or shielding of this fragment from rapid cooling, e.g., due to hovering in the center of a relatively dense cloud of debris). In addition, we calculated that the cooling from 1473 to 1100 K of the average fragment at the depth of our samples took no more than 3–4 days, suggesting that the reassembly of the ureilite daughter bodies could have been a very fast process.

^1,2Y. Li,^1,3A. Mei,^1,2W. Hsu,⁴S. Li
Journal of Geophysical Research (Planets)(in Press) Link to Article [https://doi.org/10.1029/2023JE008124]
¹Key Laboratory of Planetary Sciences, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing, China
²CAS Center for Excellence in Comparative Planetology, Hefei, China
³School of Astronomy and Space Sciences, University of Science and Technology of China, Hefei, China
⁴Astronomical Research Center, Shanghai Science & Technology Museum, Shanghai, China
Published by arrangement with John Wiley & Sons

Ca-phosphates in Campo del Cielo (CdC) and Nantan were comprehensively studied to provide insights into the thermal histories of the IAB main group (MG) and related irons. In CdC, apatite grains are characterized by (a) close intergrowth with troilite/graphite in border area between silicate and metal in most cases and (b) near-flat rare earth elemental patterns (LaN/YbN = 0.6–0.7). This indicates they were formed during a metal-silicate mixing event at a relatively high temperature. Combining with petrographic textures, we suggest that the replacement of high-Ca pyroxene by low-Ca pyroxene at ∼950–1,000°C could release Ca and facilitate the formation of apatite grains. In the Nantan nodule, Ca-phosphates do not share a similar origin with those in CdC, as indicated by their different mineral chemistries and mineral associations. Ca-phosphates and associated silicates could crystallize from a P-C-S-rich metallic melt with the oxidation of lithophile elements. Combining all analyses from CdC and Nantan yielded a SIMS Pb-Pb isochron age of 4,558 ± 56 Ma. Considering that all the IAB-MG irons experienced a rapid high-temperature cooling process, the age of 4,558 ± 56 Ma provides another line of evidence that the parent body of IAB-MG and related irons experienced metal-silicate mixing in first 50 Myr of solar system. The previously reported Ar-Ar ages of ≤4.47 Ga could be related to the late reheating process(es). The degrees of late shock heating may vary from specimen to specimen.

¹Eng, A.M. et al. (>10)
Journal of Geophysical Research (Planets)(in Press) Open Access Link to Article [https://doi.org/10.1029/2023JE008033]
¹Western Washington University, Bellingham, WA, USA
Published by arrangement with John Wiley & Sons

Since leaving Vera Rubin ridge (VRr), the Mars Science Laboratory Curiosity rover has traversed though the phyllosilicate-bearing region, Glen Torridon, and the overlying Mg-sulfate-bearing strata, with excursions onto the Greenheugh Pediment and Amapari Marker Band. Each of these distinct geologic units were investigated using Curiosity’s Mast Camera (Mastcam) multispectral instrument which is sensitive to iron-bearing phases and some hydrated minerals. We used Mastcam spectra, in combination with chemical data from Chemistry and Mineralogy, Alpha Particle X-ray Spectrometer, and Chemistry and Camera instruments, to assess the variability of rock spectra and interpret the mineralogy and diagenesis in the clay-sulfate transition and surrounding regions. We identify four new classes of rock spectra since leaving VRr; two are inherent to dusty and pyroxene-rich surfaces on the Amapari Marker Band; one is associated with the relatively young, basaltic, Greenheugh Pediment; and the last indicates areas subjected to intense aqueous alteration with an amorphous Fe-sulfate component, primarily in the clay-sulfate transition region. To constrain the Mg-sulfate detection capabilities of Mastcam and aid in the analyses of multispectral data, we also measured the spectral response of mixtures with phyllosilicates, hydrated Mg-sulfate, and basalt in the laboratory. We find that hydrated Mg-sulfates are easily masked by other materials, requiring ≥90 wt.% of hydrated Mg-sulfate to exhibit a hydration signature in Mastcam spectra, which places constraints on the abundance of hydrated Mg-sulfates along the traverse. Together, these results imply significant compositional changes along the traverse since leaving VRr, and they support the hypothesis of wet-dry cycles in the clay-sulfate transition.

¹Yves Marrocchi,¹Alizé Longeau,¹Rosa Lozano Goupil,¹Valentin Dijon,^1,2,3Gabriel Pinto,¹Julia Neukampf,¹Johan Villeneuve,⁴Emmanuel Jacquet 
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2024.03.001]
¹Centre de Recherches Pétrographiques et Géochimiques (CRPG), CNRS, UMR 7358, Nancy, France
²Royal Belgian Institute of Natural Sciences, Geological Survey of Belgium, 1000, Brussels, Belgium
³Instituto de Ciencias de la Tierra, Universidad Austral de Chile, Valdivia, Chile
⁴Institut 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

The systematic isotopic difference between refractory inclusions and chondrules, particularly for oxygen, has long indicated an isotopic evolution of the solar protoplanetary disk. However, it remains underconstrained whether such evolution continued during chondrule formation. Intrigued by past reports of the size-dependent oxygen isotopic compositions of chondrules in ordinary chondrites (OC), we analyzed type I olivine-rich chondrules of various sizes in two LL3 chondrites. Although most chondrules show positive Δ17O values comparable to bulk ordinary chondrites, a population of smaller (less than about 0.1 mm2 in cross-section), including many isolated olivine grains (sensu lato), are 16O-enriched (with Δ17O values down to −13.2 ‰). Literature data allow the same observation for R chondrites. All sub-TFL type I chondrules (i.e., Δ17O < 0) chondrules have Mg# > 97 mol% while the supra-TFL type I chondrule olivines extend to the formal boundary with type II chondrules (i.e., Mg# = 90 mol%). The sub-TFL chondrules are likely genetically related to isotopically similar aluminum-rich chondrules described in the literature. They therefore must have formed earlier than most OC and R chondrules when the inner disk was still sub-TFL. This interpretation is supported by the presence of similarly 16O-rich relict grains in supra-TFL OC and R chondrules that must be remains of this incompletely recycled precursor material. The non-carbonaceous reservoir was thus still evolving isotopically towards 16O-poorer composition when chondrule formation began, whether by mixing with outer disk material, late accretion streamers and/or an increase in the solid/gas ratio due to magnetothermal disk winds.

¹Shiori Matsubara,¹Hidenori Terasaki,²Takashi Yoshino,¹Satoru Urakawa,¹Daisuke Yumitori
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14149]
¹Department of Earth Sciences, Graduate School of Science and Technology, Okayama University, Okayama, Japan
²Institute for Planetary Materials, Okayama University, Tottori, Japan
Copyright Elsevier

In differentiated planetesimals, the liquid core starts to crystallize during secular cooling, followed by the separation of liquid–solid phases in the core. The wetting property between liquid and solid iron alloys determines whether the core melts are trapped in the solid core or they can separate from the solid core during core crystallization. In this study, we performed high-pressure experiments under the conditions of the interior of small bodies (0.5–3.0 GPa) to study the wetting property (dihedral angle) between solid Fe and liquid Fe-S as a function of pressure and duration. The measured dihedral angles are approximately constant after 2 h and decrease with increasing pressure. The dihedral angles range from 30° to 48°, which are below the percolation threshold of 60° at 0.5–3.0 GPa. The oxygen content in the melt decreases with increasing pressure and there are strong positive correlations between the S + O or O content and the dihedral angle. Therefore, the change in the dihedral angle is likely controlled by the O content of the Fe-S melt, and the dihedral angle tends to decrease with decreasing O content in the Fe-S melt. Consequently, the Fe-S melt can form interconnected networks in the solid core. In the obtained range of the dihedral angle, a certain amount of the Fe-S melt can stably coexist with solid Fe, which would correspond to the “trapped melt” in iron meteorites. Excess amounts of the melt would migrate from the solid core over a long period of core crystallization in planetesimals.