^1,2S.K. Bell,³D.J. Morgan,¹K.H. Joy,¹J.F. Pernet-Fisher,¹M.E. Hartley
Geochimica et Cosmochimica acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2023.08.009]
¹Department of Earth and Environmental Sciences, University of Manchester, Manchester, M13 9PL, UK
²Rocktype Ltd, Magdalen centre, Oxford, UK
³School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK
Copyright Elsevier

Mare basalts collected at the Apollo 15 landing site can be classified into two groups. Based on differing whole-rock major element chemistry, these groups are the quartz-normative basalt suite and the olivine-normative basalt suite. In this study we use modelling of Fe-Mg interdiffusion in zoned olivine crystals to investigate the magmatic environments in which the zonation was formed, be that within the lunar crust or during cooling within a surficial lava flow, helping to understand the thermal histories of the two basalt suites. Interdiffusion of Fe-Mg in olivine was modelled in 29 crystals in total, from six olivine-normative basalt thin sections and from three quartz-normative basalt thin sections. We used a dynamic diffusion model that includes terms for both crystal growth and intracrystalline diffusion during magma cooling. Calculated diffusion timescales range from 5 to 24 days for quartz-normative samples, and 6 to 91 days for olivine-normative samples. Similarities in diffusion timescales point to both suites experiencing similar thermal histories and eruptive processes. The diffusion timescales are short (between 5 and 91 days), and compositional zonation is dominated by crystal growth, which indicates that the diffusion most likely took place during cooling and solidification within lava flows at the lunar surface. We used a simple conductive cooling model to link our calculated diffusion timescales with possible lava flow thicknesses, and from this we estimate that Apollo 15 lava flows are a minimum of 3 to 6 m thick. This calculation is consistent with flow thickness estimates from photographs of lava flows exposed in the walls of Hadley Rille at the Apollo 15 landing site. Our study demonstrates that diffusion modelling is a valuable method of obtaining information about lunar magmatic environments recorded by individual crystals within mare basalt samples.

¹Zhongtian Zhang,¹David Bercovici
Proceedings of the National Academy of Sciences of the United States of America (PNAS) 120, 32 Link to Article [https://doi.org/10.1073/pnas.2221696120]
¹Department of Earth and Planetary Sciences, Yale University, New Haven, CT 06511

Paleomagnetic records of iron meteorites of the IVA group suggest that their parent body (an inward-solidified metal asteroid) possessed an internal magnetic field. The origin of this magnetism is enigmatic because inward solidification typically leads to light element release from the top of the liquid, which depresses convection and dynamo activity. Here, we propose a possible scenario to help resolve this paradox. The formation of a metal asteroid must involve a disruptive, mantle-stripping collision and the reaccretion of metal fragments. We hypothesize that a small portion of metal fragments may have substantially cooled before being reaccreted. These fragments could have formed a cold, rubble-pile inner core, which extracted heat from the liquid layer, leading to solidification and light element expulsion at the inner core boundary to power a dynamo. In the portions of the inward-growing crust that cooled below the remanence acquisition temperature, the magnetic field could be recorded.

¹Yunhua Wu,^2,3Weibiao Hsu,²Shiyong Liao,¹Zhiyong Xiao,⁴Xiaochao Che,⁵Lili Pan,²Ye Li,⁶Shaolin Li
Geochimica et Cosmochmica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2023.08.003]
¹Planetary Environmental and Astrobiological Research Laboratory, School of Atmospheric Sciences, Sun Yat-sen University, Zhuhai 519082, China
²CAS Center for Excellence in Comparative Planetology, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210023, China
³Deep Space Exploration Laboratory, University of Science and Technology, Hefei 230026, China
⁴Beijing SHRIMP Center, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 102206, China
⁵School of Earth Sciences and Engineering, Sun Yat-sen University, Zhuhai 519082, China
⁶Astronomical Research Center, Shanghai Science & Technology Museum, Shanghai 201306, China
Copyright Elsevier

Gabbroic and microgabbroic shergottites are intrusive igneous rocks on Mars and exhibit a wide variety of mineralogical and geochemical properties. However, their source reservoirs, magmatic processes and the link to other shergottite subtypes are not well constrained. Northwest Africa (NWA) 13581 is a newly found permafic olivine gabbro, representing a cumulate member in the shergottite group. This sample provides new critical constraints on the characteristics of mantle sources and magmatic evolution of shergottites. The texture and mineral chemistry of NWA 13581 indicate a polybaric crystallization condition, with an increase in oxygen fugacity of approximately 1 log unit after ascent and emplacement. Geochemical studies suggest that the sample is young (150 ± 25 Ma) and may share a similar enriched mantle reservoir (initial ε176Hfi = -18.4, initial ε143Ndi = -7.1) with shergottites like Zagami (basaltic shergottite), NWA 10169 (poikilitic shergottite) and Larkman Nunatak 06319 (olivine-phyric shergottite). In addition, the presence of potassium-rich melt inclusions enclosed in early-formed minerals of NWA 13581 implies a fertile source, probably originating from a metasomatized mantle. The occurrence of similar potassium-rich components in other enriched shergottites may suggest a common process in their mantle reservoir and during crystallization. Overall, NWA 13581 resembles poikilitic shergottites closer than typical gabbroic shergottites in several respects such as poikilitic texture, mineral chemistry, magmatic evolutionary path, and emplacement conditions. A simplified model is proposed for the formation of NWA 13581 and poikilitic shergottites in the same magma series. Magma mixing and/or assimilation are not the major mechanism that account for their slightly varied mineral modal abundances and quantitative textural characteristics. For samples derived from similar mantle sources, the textural and mineralogical diversities of shergottites are largely related to crystallization at different crustal levels.

^1,2Thomas J. Barrett,^1,2,3Katharine L. Robinson,^4,5Jessica J. Barnes,⁶G. Jeffrey Taylor,⁶Kazuhide Nagashima,⁶Gary R. Huss,³Ian A. Franchi,^3,7Mahesh Anand,^1,2David A. Kring 
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2023.08.004]
¹Center for Lunar Science and Exploration, Lunar and Planetary Institute, USRA, Houston, TX 77058
²NASA SSERVI
³School of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
⁴ARES, NASA Johnson Space Center, Houston TX 77058, USA
⁵Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA
⁶Hawai’i Institute of Geophysics and Planetology, University of Hawai’i at Mānoa, Honolulu, HI 96822, USA
⁷Department of Earth Sciences, Natural History Museum, London SW7 5BD, UK
Copyright Elsevier

Apollo 15 quartz monzodiorites (QMDs) are reported to contain some of the most deuterium-depleted apatite found in lunar samples. In this study, apatite from six Apollo 15 QMDs, including three samples from 15405 not previously investigated, were analyzed for their H and Cl isotopes. Apatite in 15405 are extremely 2H (or D)-poor, with δD values ranging from – 658 ± 53 to − 378 ± 113 ‰, comparable to apatite data from related samples 15403 and 15404. In addition to new H isotope data, the first Cl-isotope data for lunar QMDs are presented. Apatite in 15405 and related samples are enriched in 37Cl with respect to Earth, with measured δ37Cl values ranging from + 13 to + 37 ‰. These values are within the reported δ37Cl range for KREEP-rich samples. The fact that the Cl isotopic composition of apatite in QMDs are similar to those in other lunar lithologies, but the H isotopic data are distinct and unique, provides possible further evidence for the existence of a D-poor reservoir in the lunar interior. Raman spectroscopy of the silica polymorph in sample 15405 reveals it to be a mixture of quartz and cristobalite. Based on available experimental data on the stability of various silica phases over a range of pressure and temperature regime, a deep-seated origin in the crust for QMDs may be possible which would support an endogenous origin of the H-Cl isotope systematics of the QMDs. The role of impact-induced transformation of silica phases and its contributing towards low D/H ratio in apatite, however, cannot be ruled out.

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

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

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^1,2,3Liu, Runchuan et al. (>10)
Science China Earth Sciences 66, 1399 – 1422 Link to Article [DOI 10.1007/s11430-022-1049-4]
¹State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China
²Institutes of Earth Science, 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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¹Hoppe, Peter,²Rubin, Martin,³Altwegg, Kathrin
Space Science Reviews 219, 32 Open Access Link to Article [DOI 10.1007/s11214-023-00977-9]
¹Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, Mainz, 55128, Germany
²Physikalisches Institut, University of Bern, Sidlerstrasse 5, Bern, 3012, Switzerland
³Center for Space and Habitability, University of Bern, Sidlerstrasse 5, Bern, 3012, Switzerland

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¹Hashiguchi, Minako et al. (>10)
Earth, Planets and Space 75, 73 Open Access Link to Article [DOI 10.1186/s40623-023-01792-w]
¹Graduate School of Environmental Studies, Nagoya University, Furo-Cho, Nagoya, Chikusa-Ku, 464-8601, Japan

We performed in-situ analysis on a ~ 1 mm-sized grain A0080 returned by the Hayabusa2 spacecraft from near-Earth asteroid (162173) Ryugu to investigate the relationship of soluble organic matter (SOM) to minerals. Desorption electrospray ionization-high resolution mass spectrometry (DESI-HRMS) imaging mapped more than 200 CHN, CHO, CHO–Na (sodium adducted), and CHNO soluble organic compounds. A heterogeneous spatial distribution was observed for different compound classes of SOM as well as among alkylated homologues on the sample surface. The A0080 sample showed mineralogy more like an Ivuna-type (CI) carbonaceous chondrite than other meteorites. It contained two different lithologies, which are either rich (lithology 1) or poor (lithology 2) in magnetite, pyrrhotite, and dolomite. CHN compounds were more concentrated in lithology 1 than in lithology 2; on the other hand, CHO, CHO–Na, and CHNO compounds were distributed in both lithologies. Such different spatial distribution of SOM is likely the result of interaction of the SOM with minerals, during precipitation of the SOM via fluid activity, or could be due to difference in transportation efficiencies of SOMs in aqueous fluid. Organic-related ions measured by time-of-flight secondary ion mass spectrometry (ToF–SIMS) did not coincide with the spatial distribution revealed by DESI-HRMS imaging. This result may be because the different ionization mechanism between DESI and SIMS, or indicate that the ToF–SIMS data would be mainly derived from methanol-insoluble organic matter in A0080. In the Orgueil meteorite, such relationship between altered minerals and SOM distributions was not observed by DESI-HRMS analysis and field-emission scanning electron microscopy, which would result from differences of SOM formation processes and sequent alteration process on the parent bodies or even on the Earth. Alkylated homologues of CHN compounds were identified in A0080 by DESI-HRMS imaging as observed in the Murchison meteorite, but not from the Orgueil meteorite. These compounds with a large C number were enriched in Murchison fragments with abundant carbonate grains. In contrast, such relationship was not observed in A0080, implying different formation or growth mechanisms for the alkylated CHN compounds by interaction with fluid and minerals on the Murchison parent body and asteroid Ryugu.

^1,2Andreas Bechtold,³Gerhard Paar,⁴Filippo Garolla,⁵Rebecca Nowak,⁵Laura Fritz,⁵Christoph Traxler,⁵Oliver Sidla,^1,2Christian Koeberl
Meteoritcs & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14054]
¹Department of Lithospheric Research, University of Vienna, Vienna, Austria
²Austrian Academy of Sciences, Vienna, Austria
³Joanneum Research, Graz, Austria
⁴SLR Engineering, Graz, Austria
⁵VRVis, Vienna, Austria
Published by arrangement with John Wiley & Sons

Past, present, and forthcoming planetary rover missions to Mars and other planetary bodies are equipped with a large number of scientific cameras. The very large number of images resulting from this, combined with tight time constraints for navigation, measurements, and analyses, pose a major challenge for the mission teams in terms of scientific target evaluation. Shatter cones are the only macroscopic evidence for impact-induced shock metamorphism and therefore impact craters on Earth. The typical features of shatter cones, such as striations and horsetail structures, are particularly suitable for machine learning methods. The necessary training images do not exist for such a case; therefore, we pursued the approach of producing them artificially. Using PRo3D, a viewer developed for the interactive exploration and geologic analysis of high-resolution planetary surface reconstructions, we virtually placed shatter cones in 3-D background scenes processed from true Mars rover imagery. We use PRo3D-rendered images of such scenes as training data for machine learning architectures. Terrestrial analog studies in Ethiopia supported our lab work and were used to test the resulting neural network of this feasibility study. The result showed that our approach with shatter cones in artificial Mars rover scenes is suitable to train neural networks for automatic detection of shatter cones. In addition, we have identified several aspects that can be used to improve the training of the neural network and increase the recognition rate. For example, using background data with a higher resolution in order to have equal resolution of object (shatter cone) and Martian background and increase the number of objects that can be placed in the training data set. Also using better lighting reconstructions and a better radiometric adaption between object and Martian background would further improve the results.