^1,2Zilong Wang,¹Wei Tian
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13957]
¹The Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, School of Earth and Space Sciences, Peking University, Beijing, China
²The Key Laboratory of Paleomagnetism and Tectonic Reconstruction of MNR, Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing, China
Published by arrangement with John Wiley & Sons

Mesosiderites are breccias composed of roughly equal parts of metal phases and silicate clasts. However, the parent body and formation process of mesosiderites remain enigmatic. Northwest Africa (NWA) 12949 is a newly found mesosiderite belonging to type 2A. One type of ultramafic clasts and four types of mafic clasts (gabbroic, poikilitic, subophitic, and cataclastic), compositionally consistent with diogenites and eucrites, have been identified in NWA 12949. However, these clasts have undergone different thermal histories, with cooling rates varying from ~0.0044 °C year−1 to a few °C h−1, and equilibrium temperatures varying from ~880 to 910 °C to ~1000 to 1100 °C. All the lithic clasts have undergone redox reactions during extensive metamorphism, forming excess troilite, chromite, merrillite, tridymite, and pyroxene with lower Fe/Mg and Fe/Mn. The petrology and mineralogy of NWA 12949 support a formation scenario involving two major impact events, and a candidate parent body of 4 Vesta.

¹Dagmara Oszkiewicz,¹Hanna Klimczak,²Benoit Carry,³Antti Penttilä,⁴Marcel Popescu,¹Joachim Krüger,^5,6Marcelo Aron Keniger
Monthly Notices of the Royal Astronomical Society 519, 2917–2928 Link to Article[https://doi.org/10.1093/mnras/stac3442]
¹Astronomical Observatory Institute, Faculty of Physics, Adam Mickiewicz University, Słoneczna 36, P-60-286 Poznań, Poland
²Observatoire de la Côte d’Azur, CNRS, Université Côte d’Azur, Laboratoire Lagrange, 06304 Nice, France
³Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
⁴Astronomical Institute of the Romanian Academy, 5 Cutitul de Argint, 040557 Bucharest, Romania
⁵Nordic Optical Telescope, Rambla José Ana Fernández Pérez 7, E-38711 Breña Baja, Spain
⁶Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark

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¹E. Hasenstab-Dübeler,¹C. Münker,¹J. Tusch,^1,2M.M. Thiemens,³ D. Garbe-Schönberg,⁴E. Strub,⁵P. Sprung
Earth and Planetary Science Letters 606, 118018 Link to Article [https://doi.org/10.1016/j.epsl.2023.118018]
¹Institut für Geologie und Mineralogie, Universität zu Köln, Köln, Germany
²Laboratoire G-Time, Département Géosciences, Environnement et Société, Université Libre de Bruxelles, Brussels, Belgium
³Institut für Geowissenschaften, Christian-Albrechts- Universität zu Kiel, 24118 Kiel, Germany
⁴Division of Nuclear Chemisty, University of Cologne, 50674 Cologne, Germany
⁵Hot Laboratory Division (AHL), Paul Scherrer Institut, Villigen, Switzerland
Copyright Elsevier

The Moon is a key example of a planetary body that originated from a giant impact collisional event. By better understanding its bulk composition, we gain critical constraints on the building blocks of the Earth-Moon system. Combined measurements of long-lived 147Sm-143Nd and short-lived 146Sm-142Nd isotope compositions of Earth and Moon have lead to controversial interpretations in the past and it remains ambiguous, whether or not the Moon is similar to primitive chondrites in its refractory lithophile element composition. We investigated coupled 138La-138Ce and 147Sm-143Nd isotope and trace element compositions across a wide range of lunar rock types to provide an independent assessment of the bulk Moon composition. All measured lunar rocks define a tight array in 138Ce-143Nd space, intersecting initial
at an initial εCe
, significantly lower than the currently accepted chondritic 138Ce reference value. The results of combined modeling of 138Ce-143Nd-176Hf isotope and trace element behavior during lunar magma ocean (LMO) crystallization are in good agreement with the bulk silicate Moon having a slight depletion in its highly incompatible trace element inventory. Our calculated composition of the silicate Moon evolves towards
and εNd =+1.4 at 3.30 Ga, the approximate age of most lunar samples investigated here. This proposed lunar isotope composition at 3.30 Ga agrees well with the intersection of the
Ga lunar array and the terrestrial array defined by rocks from the Archean Pilbara and the Kaapvaal Cratons. We take this as evidence that accessible silicate Earth and the Moon may share a common reservoir slightly depleted in highly incompatible trace elements, named here Slightly Depleted Earth-Moon reservoir (SDEM). The SDEM reservoir proposed here is generally in line with previous models claiming a depleted composition of the accessible silicate Earth, but the degree of depletion is significantly smaller than previously proposed.

¹Pavol Matlovič et al. (>10)
Monthly Notices of the Royal Astronomical Society 513, 3982-3992 Link to Article [https://doi.org/10.1093/mnras/stac927]
¹Faculty of Mathematics, Physics and Informatics, Comenius University in Bratislava, Mlynska dolina, 84248 Bratislava, Slovakia

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^1,2D Morate,³M Popescu,^1,2J Licandro,^1,2F Tinaut-Ruano,^1,4E Tatsumi,^1,2J de León
Monthly Notices of the Royal Astronomical Society 519, 1677-1687 Link to Article [https://doi.org/10.1093/mnras/stac3530]
¹Instituto de Astrofísica de Canarias (IAC), C/Vía Láctea s/n, E-38205 La Laguna, Tenerife, Spain
²Departamento de Astrofísica, Universidad de La Laguna, E-38205 La Laguna, Tenerife, Spain
³Astronomical Institute of the Romanian Academy, 5 Cuţitul de Argint, 040557 Bucharest, Romania
⁴Department of Earth and Planetary Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-0033 Tokyo, Japan

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¹Andrea Corpolongo et al. (>10)
Journal of Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2022JE007455]
¹Department of Geology, University of Cincinnati, Cincinnati, OH, USA
Published by arrangement with John Wilely & Sons

The goals of NASA’s Mars 2020 mission include searching for evidence of ancient life on Mars, studying the geology of Jezero crater, understanding Mars’ current and past climate, and preparing for human exploration of Mars. During the mission’s first science campaign, the Perseverance rover’s SHERLOC deep UV Raman and fluorescence instrument collected microscale, two-dimensional Raman and fluorescence images on ten natural (unabraded) and abraded targets on two different Jezero crater floor units: Séítah and Máaz. We report SHERLOC Raman measurements collected during the Crater Floor Campaign and discuss their implications regarding the origin and history of Séítah and Máaz. The data support the conclusion that Séítah and Máaz are mineralogically distinct igneous units with complex aqueous alteration histories and suggest that the Jezero crater floor once hosted an environment capable of supporting microbial life and preserving evidence of that life, if it existed.

¹J.I.Simon et al. (>10)
Journal of Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2022JE007474]
¹Center for Isotope Cosmochemistry and Geochronology, Astromaterials Research and Exploration Science, NASA Johnson Space Center, Houston, TX, USA
Published by arrangement with John Wiley & Sons

The first samples collected by the Mars 2020 mission represent units exposed on the Jezero Crater floor, from the potentially oldest Séítah formation outcrops to the potentially youngest rocks of the heavily cratered Máaz formation. Surface investigations reveal landscape-to-microscopic textural, mineralogical, and geochemical evidence for igneous lithologies, some possibly emplaced as lava flows. The samples contain major rock-forming minerals such as pyroxene, olivine, and feldspar, accessory minerals including oxides and phosphates, and evidence for various degrees of aqueous activity in the form of water-soluble salt, carbonate, sulfate, iron oxide, and iron silicate minerals. Following sample return, the compositions and ages of these variably altered igneous rocks are expected to reveal the geophysical and geochemical nature of the planet’s interior at the time of emplacement, characterize martian magmatism, and place timing constraints on geologic processes, both in Jezero Crater and more widely on Mars. Petrographic observations and geochemical analyses, coupled with geochronology of secondary minerals, can also reveal the timing of aqueous activity as well as constrain the chemical and physical conditions of the environments in which these minerals precipitated, and the nature and composition of organic compounds preserved in association with these phases. Returned samples from these units will help constrain the crater chronology of Mars and the global evolution of the planet’s interior, for understanding the processes that formed Jezero Crater floor units, and for constraining the style and duration of aqueous activity in Jezero Crater, past habitability, and cycling of organic elements in Jezero Crater.

¹Ming Ma,¹Jingran Chen,²Clive R. Neal,^3,4Shengbo Chen,¹Bingze Li,¹Chenghao Han,¹Peng Tian
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2023.115464]
¹School of Surveying and Exploration Engineering, Jilin Jianzhu University, Changchun, China
²Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
³School of Geo-Exploration Science and Techniques, Jilin University, Changchun, China
⁴Center for Excellence in Comparative Planetology, Chinese Academy of Sciences, Hefei, China
Copyright Elsevier

High alumina (HA) mare basalts play unique roles in understanding the heterogeneity of lunar mantle. Their presence was confirmed by the Apollo and Luna samples, and their remote sensing identification was implemented using HA sample FeO, TiO₂ and Th concentration constraints. This study selected the surfaces with ~0.5% rock abundance as windows into HA basalts identification. The lithology of these rock pixels was first classified based on thorium maps from the Lunar Prospector and major element oxide products from Diviner data onboard the Lunar Reconnaissance Orbiter (LRO). Then, the LRO Diviner Al₂O₃ (~11 wt%) concentration constraint was applied in the mare basalt rock pixels across the Moon. The mare-highland mixtures were distinguished from HA basalt rocks based on the positive linear relationships between Al₂O₃ and Mg# in the adjacent pixels for four impact vector directions away from each candidate HA pixel. These HA basalts rock pixels identified by this study indicate that HA basalts are concentrated locally in South Pole-Aitken (SPA) basin, Schiller-Schickard region and 13 maria such as southern and northern Oceanus Procellarum, central Humorum, Tranquillitatis, Fecunditatis and Serenitatis, northern Imbrium and southern Nubium, but are seldom found in Mare Moscoviense and Orientale regions on the farside. Detailed investigations in Mare Fecunditatis found that fifteen HA basalt units or patches could be confidently identified. These HA basalts have the total area and volume of <77,658 km² and < 54,301 km³, and the maximum depth and thickness of 1147 m and 1062 m respectively. In addition, analyses of the HA rocks indicated that the HA basalts are discontinuous and have variable thicknesses.

¹Zhongtian Zhang,¹David Bercovici,²Linda T. Elkins-Tanton
Earth and Planetary Science Letters (in Press) Link to Article [https://doi.org/10.1016/j.epsl.2023.118019]
¹Department of Earth and Planetary Sciences, Yale University, New Haven, CT, USA
²School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
Copyright Elsevier

Primitive achondrites represent residual mantle material of planetesimals from which up to 20% partial melts were extracted. Melting experiments on chondritic compositions suggest that melts produced by ≲20% partial melting are rich in silica and alkali elements. Such melts are highly viscous (≳103Pa⋅s), and percolation models predict that they would only migrate negligible distances over timescales of 1–10Myr. After these timescales, a planetesimal would either be melted into a magma ocean by radiogenic heating from Al26, if it formed early; or it would cool below solidus, if it formed relatively late. However, melt migration is also controlled by permeability, which could be high for aggregates of rock boulders (compared to those of mineral grains). Specifically, the theory of planet formation suggests that collisions occurred frequently between planetesimals in the early solar system. These collisions may have shattered the planetesimals into fragments with sizes of meters to tens of meters, which would have accreted gravitationally into one or more daughter bodies. We develop a model to investigate melt migration in “rubble-pile” planetesimals; in particular, the melt exchange between partially molten rock boulders and the void space between them. The results suggest that, with typical properties of primitive achondrite materials at the conditions of low-degree partial melting, melts may have been squeezed into the voids between boulders, and migrated rapidly through these channels. Therefore, primitive achondrites may record melt migration in rubble-pile bodies reaccreted from fragments of partially molten planetesimals.

¹Laura E. Jenkins,¹Martin R. Lee,^1,2,3Luke Daly,⁴Ashley J. King,¹Cameron J. Floyd,¹Pierre-Etienne Martin,⁴Natasha V. Almeida,⁵Matthew J. Genge
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.13949]
¹School of Geographical and Earth Sciences, The University of Glasgow, Glasgow, G12 8RZ UK
²Space Science and Technology Centre, School of Earth and Planetary Sciences, Curtin University, Perth, Western Australia, 6845 Australia
³Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, New South Wales, 2006 Australia
⁴Planetary Materials Group, Natural History Museum, London, SW7 5BD UK
⁵Department of Earth Science and Engineering, Imperial College London, London, SW7 2AZ UK
Published by arrangement with John Wiley & Sons

Winchcombe is a CM chondrite that fell in England on February 28, 2021. Its rapid retrieval was well characterized. Within two polished sections of Winchcombe, terrestrial phases were observed. Calcite and calcium sulfates were found in a sample recovered from a field on March 6, 2021, and halite was observed on a sample months after its recovery from a driveway on March 2, 2021. These terrestrial phases were characterized by scanning electron microscopy, Raman spectroscopy, and transmission electron microscopy. Calcite veins crosscut the fusion crust and therefore postdate it. The calcite likely precipitated in the damp environment (sheep field) where the meteorite lay for six days prior to its retrieval. The sulfates occur on the edges of the sample and were identified as three minerals: gypsum, bassanite, and anhydrite. Given that the sulfates occur only on the sample’s edges, including on top of the fusion crust, they formed after Winchcombe fell. Sulfate precipitation is attributed to the damp fall environment, likely resulted from sulfide-derived H2S reacting with calcite within the meteorite. Halite occurs as euhedral crystals only on the surface of a polished section and exclusively in areas relatively enriched in sodium. It was likely produced by the interaction of the polished rock slice with the humid laboratory air over a period of months. The sulfates, fusion crust calcite, and halite all post-date Winchcombe’s entry into the Earth’s atmosphere and showcase how rapidly meteorite falls can be terrestrially altered.