¹Clara Maurel,¹Jérôme Gattacceca
Proceedings of the National Academy of Science of America (PNAS) 121, e2312802121 Link to Article [https://doi.org/10.1073/pnas.23128021]
¹CNRS, Aix Marseille Université, IRD, INRAE, Centre de Recherche et d’Enseignement des Géosciences de l’Environnement (CEREGE), Aix-en-Provence 13545, France

Magnetic fields in protoplanetary disks are thought to play a prominent role in the formation of planetary bodies. Acting upon turbulence and angular momentum transport, they may influence the motion of solids and accretion onto the central star. By searching for the record of the solar nebula field preserved in meteorites, we aim to characterize the strength of a disk field with a spatial and temporal resolution far superior to observations of extrasolar disks. Here, we present a rock magnetic and paleomagnetic study of the andesite meteorite Erg Chech 002 (EC002). This meteorite contains submicron iron grains, expected to be very reliable magnetic recorders, and carries a stable, high-coercivity magnetization. After ruling out potential sources of magnetic contamination, we show that EC002 most likely carries an ancient thermoremanent magnetization acquired upon cooling on its parent body. Using the U-corrected Pb-Pb age of the meteorite’s pyroxene as a proxy for the timing of magnetization acquisition, we estimate that EC002 recorded a field of 60 ± 18 µT at a distance of ~2 to 3 astronomical units, 2.0 ± 0.3 My after the formation of calcium-aluminum-rich inclusions. This record can only be explained if EC002 was magnetized by the field prevalent in the solar nebula. This makes EC002’s record, particularly well resolved in time and space, one of the two earliest records of the solar nebula field. Such a field intensity is consistent with stellar accretion rates observed in extrasolar protoplanetary disks.

^1,2,3Fan Liu,^3,4,5,6,7,8Yuan-Sen Ting,^3,4David Yong,^9,10Bertram Bitsch,^1,3Amanda Karakas,²Michael T. Murphy,^11,12Meridith Joyce,¹³Aaron Dotter,^14,15Fei Dai
Nature 627, 501-504 Link to Article [DOI https://doi.org/10.1038/s41586-024-07091-y]
¹School of Physics and Astronomy, Monash University, Clayton, Victoria, Australia
²Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, Victoria, Australia
³ARC Centre for All Sky Astrophysics in 3D (ASTRO-3D), Canberra, Australian Capital Territory, Australia
⁴Research School of Astronomy and Astrophysics, Australian National University, Weston, Australian Capital Territory, Australia
⁵School of Computing, Australian National University, Acton, Australian Capital Territory, Australia
⁶Department of Astronomy, The Ohio State University, Columbus, OH, USA
⁷Center for Cosmology and AstroParticle Physics (CCAPP), The Ohio State University, Columbus, OH, USA
⁸Observatories of the Carnegie Institution of Washington, Pasadena, CA, USA
⁹Max-Planck-Institut für Astronomie, Heidelberg, Germany
¹⁰Department of Physics, University College Cork, Cork, Ireland
¹¹HUN-REN Research Centre for Astronomy and Earth Sciences, Konkoly Observatory, Budapest, Hungary
¹²CSFK, MTA Centre of Excellence, Budapest, Hungary
¹³Department of Physics and Astronomy, Dartmouth College, Hanover, NH, USA
¹⁴Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
¹⁵Department of Astronomy, California Institute of Technology, Pasadena, CA, USA

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^1,2Qadri S.B.,²Goswami R.,²Imler G.,²Qadri S.N.
Materialia 33, 102035 Link to Article [DOI 10.1016/j.mtla.2024.102035]
¹Retired Emeritus, US Naval Research Laboratory, Washington, 20375, DC, United States
²Materials Science and Technology Division, US Naval Research Laboratory, Washington, 20375, DC, United States

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¹Agrosì, Giovanna, ²Manzari, Paola,¹Mele, Daniela,¹Tempesta, Gioacchino, ¹Rizzo, Floriana,³Catelani, Tiziano,⁴Bindi, Luca
Communications Earth and Environment 5, 67 Open Access Link to Article [DOI 10.1038/s43247-024-01233-w]
¹Dipartimento di Scienze della Terra e Geoambientali, Università degli Studi di Bari Aldo Moro, Via Orabona 4, Bari, I-70125, Italy
²Agenzia Spaziale Italiana, Centro Spaziale di Matera, Matera, Terlecchia, I-75100, Italy
³Centro Servizi MEMA, Università di Firenze, Via Capponi 3r, Florence, I-50121, Italy
⁴Dipartimento di Scienze della Terra, Università di Firenze, Via La Pira 4, Florence, I-50121, Italy

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^1,2Chang Nie,^3,4Jin-Ting Kang,¹Yun Jiang,³Si-Jie Wang,^3,4Fang Huang,^1,2,4Wei-Biao Hsu
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2024.03.009]
¹Center for Excellence in Comparative Planetology, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210023, China
²School of Astronomy and Space Science, University of Science and Technology of China, Hefei 230026, China
³CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China
⁴Deep Space Exploration Laboratory, University of Science and Technology of China, Hefei 230026, China
Copyright Elsevier

Stable strontium and barium isotopes are potential tracers for understanding planetary differentiation and the nature of the building blocks of terrestrial planets. Strontium and barium are fluid-mobile elements, but it remains unclear how terrestrial weathering affects the Sr-Ba isotopes compositions in achondrites, thus hampering the utility of Sr-Ba isotopes in cosmochemistry. In this study, we conducted acetic acid leaching on three eucrites with varying weathering degrees (fall: Qiquanhu, hot desert find: Northwest Africa (NWA) 13583, and Antarctic find: Grove Mountains (GRV) 13001). Combined with detailed petrography observations and major and trace element analyses, we investigated the variations in Sr-Ba isotopes during terrestrial weathering. The degree of weathering follows an order of: NWA 13583 > GRV 13001 > Qiquanhu, evaluated based on several alteration signs, including: the presence of secondary carbonate, the enrichment of large ion lithophile elements (e.g., Sr, Ba, and U), and the Ce and Eu anomalies. The concentrations of Sr and Ba in the leachates of NWA 13583 show a good correlation with Ca, suggesting that the soluble Sr and Ba are derived from secondary carbonate. Differently, the concentrations of Sr and Ba in the leachates of Qiquanhu correlate with Al and Na, suggesting that the soluble Sr and Ba in Qiquanhu are derived from primary plagioclases. This also indicates that silicates dissolution may be inevitable in an acid leaching experiment for achondrites, even when using weak acetic acid. GRV 13001 shows no variation in Sr and Ba isotopes during leaching experiments. The δ138/134Ba in the leachate (0.26 ± 0.02 ‰) of Qiquanhu is higher than that of the residue (0.04 ± 0.03 ‰), reflecting that aqueous fluids preferentially uptake heavy Ba isotopes during plagioclase dissolution. Conversely, the leachate of NWA 13583 shows lower δ138/134Ba (-0.19 ± 0.05 ‰) than that of residue (-0.10 ± 0.03 ‰), reflecting the lighter Ba isotope composition in carbonate. Notably, the residue of NWA 13583 has δ138/134Ba ∼ 0.1 ‰ lower than those of Qiquanhu and GRV 13001. This discrepancy may reflect plagioclase dissolution during hot-desert weathering rather than magmatism on the parent body. Different from Ba isotopes, the δ88/86Sr of Qiquanhu shows no variation in the leaching experiment, suggesting that the dissolution of plagioclase causes no Sr isotope fractionation. For NWA 13583, the δ88/86Sr of leachate is slightly heavier than that of leaching residue and bulk rock, reflecting high δ88/86Sr in terrestrial fluids. Our results suggest that Ba and Sr isotopes of eucrites show different behaviors during terrestrial weathering. Sr isotopes show a smaller fractionation scale and may have greater resistance for terrestrial weathering than Ba isotopes.

¹Tai-Jan Huang,¹Eshan Ganju,¹Hamid Torbatisarraf,²Michelle S. Thompson,¹Nikhilesh Chawla
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14157]
¹School of Materials Engineering, Purdue University, West Lafayette, Indiana, USA
²Department of Earth, Atmospheric, and Planetary Science, Purdue University, West Lafayette, Indiana, USA
Published by arrangement with John Wiley & Sons

The microstructural characterization of lunar agglutinate samples serves many essential purposes in lunar science and cosmochemistry, from understanding the formation process of lunar regolith to preparing for human activity on the Moon. In this study, an advanced correlative characterization methodology was employed to examine the microstructure of a lunar agglutinate particle retrieved from the Apollo 11 mission. The multimodal characterization efforts were centered around 3-D x-ray computed tomography (XCT) and were complemented by 2-D techniques, including scanning electron microscopy and energy-dispersive x-ray spectroscopy. The nondestructive nature of the XCT allowed us to preserve the lunar dust particles, while its 3-D nature allowed us to extract meaningful microstructural information inaccessible via traditional 2-D characterization techniques. The multimodal correlative analysis further allowed us to identify the compositional and microstructural features of the agglutinate. These observations were linked to the formation process of the agglutinate to inform a hypothesis on the dynamic formation sequence of lunar regolith.

^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

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