¹Harry Y. McSween Jr.,²James W. Head III,³A. Deanne Rogers,⁴Mariek E. Schmidt
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14057]
¹Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, Tennessee, USA
²Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, Rhode Island, USA
³Department of Geosciences, Stony Brook University, Stony Brook, New York, USA
⁴Department of Earth Sciences, Brock University, St. Catharines, Ontario, Canada
Published by arrangement with John Wiley & Sons

Global magmatic trends inferred from gamma-ray, visible/near-infrared, and thermal infrared spectrometers on Mars-orbiting spacecraft have been used to constrain planetary petrogenetic processes and global thermal evolution models. Inferred magmatic trends include temporal variations in the relative proportions of low-Ca and high-Ca pyroxenes, and in the abundances of potassium (and total alkalis), silica, FeO* (total iron expressed as FeO), and thorium. These patterns are evaluated for consistency with the compositions of surface igneous rocks of different ages analyzed by Mars rovers and of martian meteorites. Trends of decreasing low-Ca pyroxene/total pyroxene ratios and of decreasing potassium (and total alkalis), with time are generally supported by surface rock analyses. However, significant differences in the GRS-measured silica in Amazonian volcanoes and in martian meteorites of equivalent age result from contamination by silica-rich dust and are problematic for a silica trend. Comparison of FeO* in Noachian and Amazonian surface data shows no decrease. An inferred temporal trend in thorium is in conflict with the complex enrichment and depletion patterns of incompatible trace elements in martian meteorites of various ages. A dearth of analyses of Hesperian-age surface rocks precludes a firm evaluation of inferred Noachian-Hesperian trends and Hesperian-Amazonian trends, but abundant Noachian rocks and a few Hesperian rocks at rover sites, and Amazonian martian meteorites, collectively representing at least 16 surface locations, afford useful comparisons with orbital remote-sensing data.

¹Huidobro, Jennifer,¹Aramendia, Julene,¹García-Florentino, Cristina,¹Población, Iratxe,¹Castro, Kepa,¹Arana, Gorka,¹Madariaga, Juan Manuel
Journal of Raman Spectroscopy (in Press) Open Access Link to Article [DOI 10.1002/jrs.6558]
¹Department of Analytical Chemistry, University of the Basque Country (UPV/EHU), Bilbao, Spain

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¹J. F. Pernet-Fisher,¹K. H. Joy,¹M. E. Hartley
Journal of Geophysical Research (Planets)(in Press) Link to Article [https://doi.org/10.1029/2022JE007570]
¹Department of Earth and Environmental Sciences, University of Manchester, Oxford Road, Manchester, M13 9PL UK
Published by arrangement with John Wiley & Sons

Rocks of the lunar granulite suite are the product of high-temperature metamorphism within the Moon’s crust. However, to date, their formation conditions have few constraints. Here we combine Ti-in-pyroxene element diffusion modelling and two-pyroxene thermometry with thermal modelling of the lunar crust in order to assess potential heat sources that could generate granulite metamorphism within the lunar highland crust. For the samples investigated in this study, the pyroxene crystals experienced peak metamorphic temperatures between ∼1027 and 1091 ºC over timescales ranging from ∼153 years to ∼15.1 kyrs. To best satisfy these temperature and timescale constraints, hot (∼2300 ºC) impact melt sheets with thickness ranging from 350 m to 3.35 km – equating to impact crater diameters between ∼60 and 280 km – have the potential to heat the underlying anorthositic crust. Deep (>20 km) igneous bodies, such as the large (>10 km thick) sills observed by the GRAIL mission near the base of the lunar crust, also have the potential to generate the required peak metamorphic temperatures; however, the thermal equilibration timescales in this scenario are modelled to be much larger (> 100 kyrs) than was witnessed by the granulites investigated. Our modelling highlights that, while lunar granulites are only a minor component within the Apollo and meteorite collection, they are likely an important and ubiquitous lithology within the lunar highland crust.

^1,2M. Darby Dyar,¹Sydney M. Wallace,^1,2Thomas H. Burbine,³Daniel R. Sheldon
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2023.115718]
¹Planetary Science Institute, 1700 East Fort Lowell, Suite 106, Tucson, AZ 85719-2395, USA
²Department of Astronomy, Mount Holyoke College, 50 College St., South Hadley, MA 01075, USA
³College of Information and Computer Sciences | 140 Governors Dr., Amherst, MA 01003, USA
Copyright Elsevier

Understanding the distribution of matter within our Solar System requires a robust methodology for evaluating the composition of small objects in the asteroid belt. Existing asteroid taxonomies have variously been based on spectral features relating to mineralogy and on classification of asteroid spectra alone. This project tests a fundamentally different approach, using machine learning algorithms to classify asteroids based on spectroscopic characteristics of existing meteorite classes. After evaluating four classification techniques built on labeled meteorite spectral data, logistic regression (LR) was determined to provide the most accurate results that distinguish eight robust groups of meteorite classes to which asteroid spectra can then be matched. The groups are rooted in mineralogical composition and directly relate meteorites to potential host bodies. A standalone LR algorithm classifies unknown asteroid spectra uniquely as one of eight specific group, allowing the distribution of compositions in the asteroid belt to be evaluated.

¹Qi, Xiaobin,^1,2Ling, Zongcheng,¹Liu, Ping,¹Chen, Jian,¹Cao, Haijun,¹Liu, Changqing,¹Wang, Xiaoyu,¹Liu, Yiheng
Eartzh and Space Science 10, e2023EA002825 Open Access Link to Article [DOI 10.1029/2023EA002825]
¹Shandong Key Laboratory of Optical Astronomy and Solar—Terrestrial Environment, School of Space Science and Physics, Institute of Space Sciences, Shandong University, Weihai, China
²CAS Center for Excellence in Comparative Planetology, Chinese Academy of Sciences, Hefei, China

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^1,2,3Gerrit ³ L.H. Tissot,^2,4Thorsten Kleine,³Ren T. Marquez
Geochemistry (Chemie der Erde) (in Press) Link to Article [https://doi.org/10.1016/j.chemer.2023.126007]
¹Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912, USA
²Institut für Planetologie, University of Münster, 48149 Münster, Germany
³The Isotoparium, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
⁴Max Planck Institute for Solar System Research, 37077 Göttingen, Germany
Copyright Elsevier

Mass-independent (nucleosynthetic) Mo isotope anomalies are uniquely useful for constraining genetic relationships among meteoritic and planetary materials and, by extension, the origin and nature of Earth’s late-stage building blocks. The meaningful interpretation of such data, however, critically depends on the accurate correction of any natural and analytical mass-dependent isotope fractionation, which is commonly assumed to follow the ‘exponential law’. Here, using new high-precision Mo isotope data for a diverse set of terrestrial samples, we show that mass-dependent Mo isotope fractionation in nature typically does not adhere to this law, but is instead dominated by equilibrium and Rayleigh processes. We demonstrate that even moderate degrees of such non-exponential fractionation (i.e., mass-dependent isotope fractionation deviating from the exponential law) can result in significant spurious mass-independent Mo isotope anomalies that, when misinterpreted as nucleosynthetic anomalies, can lead to erroneous conclusions, particularly with respect to Earth’s accretion history. Consequently, assessing the magnitude and origin of mass-dependent fractionation will be essential for future efforts to precisely determine the mass-independent Mo isotope composition of bulk silicate Earth and to identify potential nucleosynthetic isotope anomalies in terrestrial rocks.

^1,2Tang, Xuhai,¹Xu, Jingjing,¹Zhang, Yiheng,³Zhao, Haifeng,⁴Paluszny, Adriana,³Wan, Xue,¹Wang, Zhengzhi
Engineering Geology 321, 107154 Link to Article [DOI 10.1016/j.enggeo.2023.107154]
¹School of Civil Engineering, Wuhan University, Hubei, Wuhan, 430072, China
²Wuhan University Shenzhen Research Institute, Shenzhen, 518057, China
³Technology and Engineering Center for Space Utilization, Chinese Academy of Sciences, Beijing, 100094, China
⁴Department of Earth Science and Engineering, Imperial College, London, United Kingdom#

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^1,2Peters, Sophia,^1,2Semenov, Dmitry A.,³Hochleitner, Rupert,^1,2Trapp, Oliver
Scientific Reports (in Press) Open Access Link to Article [DOI 10.1038/s41598-023-33741-8]
¹Department of Chemistry, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, Munich, 81377, Germany
²Max Planck Institute for Astronomy, Königstuhl 17, Heidelberg, 69117, Germany
³Mineralogische Staatssammlung München, Theresienstr. 41, Munich, 80333, Germany

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¹Yumoto, Koki, ¹Cho, Yuichiro, ^2,3Kameda, Shingo, ¹Kasahara, Satoshi, ^1,4,5Sugita, Seiji
Spectrochimica Acta – Part B Atomic Spectroscopy 205, 106696 Link to Article [DOI
10.1016/j.sab.2023.106696]
¹Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, Japan
²Department of Physics, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima, Tokyo, 171-8501, Japan
³Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Kanagawa, Sagamihara, 252-5210, Japan
⁴Research Center of Early Universe, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, Japan
⁵Planetary Exploration Research Center, Chiba Institute of Technology, Narashino, 275-0016, Japan

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^1,2V. Fortier,²V. Debaille,^1,3V. Dehant,⁴B. Bultel
Planetary and Space Science (in Press) Link to Article [https://doi.org/10.1016/j.pss.2023.105749]
¹Earth and Life Institute, Université Catholique de Louvain-la-Neuve, Louvain-la-Neuve, Belgium
²Laboratoire G-Time, Université libre de Bruxelles, Bruxelles, Belgium
³Royal Observatory of Belgium, Bruxelles, Belgium
⁴Geosciences Paris Saclay, Université Paris-Saclay, Paris, France

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