¹Wang, Jin,¹Li , Detian,²Liu, Kun,¹Yan, Chunjie,²Qing, Gang,¹Wang, Chunyong
Zhenkong Kexue yu Jishu Xuebao/Journal of Vacuum Science and Technology 43, 271 – 289 Link to Article [DOI 10.13922/j.cnki.cjvst.202210018]
¹Science and Technology on Vacuum Technology and Physics Laboratory, Lanzhou Institute of Physics, Lanzhou, 730000, China
²School of Mechanical Engineering and Automation, Northeastern University, Shenyang, 110819, China

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^1,2Liu, Xianfeng et al. (>10)
Space Science Reviews 219, 43 Link to Article [DOI 10.1007/s11214-023-00987-7]
¹Key Laboratory of Space Active Opto-electronics Technology, Shanghai Institute of Technical Physics, Chinese Academy of Sciences (CAS), Shanghai, 200083, China
²Key Laboratory of Lunar and Deep Space Exploration, National Astronomical Observatories, CAS, Beijing, 100101, China

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¹Wang, Xu,¹Zhang, Guozhuo,¹Li, Angze,¹Wang, Yun,¹Cui, Han,¹Zhao, Weiqian,¹Qiu, Lirong
Spectrochimica Acta -Part B Atomic Spectroscopy 207, 106759 Link to Article [DOI 10.1016/j.sab.2023.106759]
¹MIIT Key Laboratory of Complex-filed Intelligent Exploration, School of Optics and Photonics, Beijing Institute of Technology, Beijing, 100081, China

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^1,2Amanda C. Stadermann,¹Jessica J. Barnes,³Timmons M. Erickson,²Tabb C. Prissel,⁴Zachary D. Michels
Journal of Geophysical Research (Planets) (in Press) Open Access Link to Article [https://doi.org/10.1029/2022JE007728]
¹Lunar and Planetary Laboratory, University of Arizona, 1629 E University Blvd, Tucson, AZ, 85721 USA
²Astromaterials Research and Exploration Science at NASA Johnson Space Center, 2101 NASA Parkway, Houston, TX, 77058 USA
³Jacobs JETS at NASA Johnson Space Center, 2101 NASA Parkway, Houston, TX, 77058 USA
⁴Department of Geosciences, University of Arizona, 1040 E 4th St, Tucson, AZ, 85721 USA
Published by arrangement with John Wiley & Sons

The magnesian suite (Mg-suite) of rocks record some of the earliest intrusive magmatism on the Moon. Studies of these Mg-suite rocks find they are plutonic or hypabyssal, formed typically kilometers under the lunar surface. Several models exist to explain the formation and evolution of the Mg-suite but distinguishing between hypotheses can be difficult given limited sample availability. The global extent of Mg-suite magmatism remains in debate and is key to constraining models of early secondary crust building. In this study, we present magnesian clasts within Apollo impact melt rock 68815. These clasts contain olivine, plagioclase, with minor amounts of Mg-Al-spinel and pyroxene similar to spinel troctolites of the Mg-suite, but they lack plutonic textures. We provide evidence that some of the clasts may be of extrusive volcanic origin akin to terrestrial komatiites while others might represent crystalline impact melts. There exists a large breadth of evidence for Mg-suite intrusives, whereas here we present possible evidence of Mg-rich volcanic counterparts. If valid, this would broaden the known diversity of lunar volcanism during the initial stages of secondary crust building. We anticipate this finding to provide a greater constraint onto models of Mg-suite ascent and emplacement, which only currently consider intrusive magmatism, as well as a renewed motivation to examine impact melt breccias for rare and understudied lithologies. Future trace element studies or radiometric dating could be used to further interrogate the connections of these clasts to the Mg-suite.

¹Robert M. Hazen et al. (>10)
Journal of Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2023JE007865]
¹Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC, 20015 USA
Published by arrangement with John Wiley & Sons

A systematic survey of 161 known and postulated minerals originating on Mars points to 20 different mineral-forming processes (paragenetic modes), which are a subset of formation modes observed on Earth. The earliest martian minerals, as on Earth, were primary phases from mafic igneous rocks and their ultramafic cumulates. Subsequent primary igneous minerals were associated with products of limited fractional crystallization, including alkaline and quartz-normative lithologies. Significant mineral diversification occurred via precipitation of primary phases from aqueous and atmospheric fluids, including authigenesis, hydrothermal and cryogenic precipitation, and evaporites, including freeze drying during eras of low atmospheric pressures. In particular, hydrothermal mineral formation associated with both volcanic fluids and sustained hydrothermal activity in impact fracture zones may have triggered significant mineral diversification, though as yet undocumented. At least 65 such primary minerals have been identified by flown missions to Mars and from martian meteorites. A host of secondary martian minerals were produced by near-surface processes related to water/rock interactions, including hydration/dehydration, oxidation/reduction, serpentinization, metasomatism, and a variety of diagenetic alterations. Additional mineral diversity resulted from metamorphic events, including thermal and shock metamorphism, lightning, and bolide impacts. However, several dominant sources of mineral diversity on Earth, including: (1) extensive fluid/rock interactions and element concentration associated with plate tectonics; (2) high-pressure regional metamorphism associated with plate tectonics; and (3) biologically mediated mineralization—are not known to be in play on Mars. Consequently, we estimate the total mineral diversity of Mars to be an order of magnitude smaller than on Earth.

¹Michael S. Phillips,¹Scott L. Murchie,¹Frank P. Seelos,¹Katie M. Hancock,^1,2Christina Selby,¹Ryan T. Poffenbarger,¹David C. Stephens,^1,3Maia Kawamura
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2023.115712]
¹The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
²MAXAR Technologies, Arlington, VA, USA
³Department of Physics and Astronomy, Dartmouth College, Hanover, NH, USA
Copyright Elsevier

The CRISM instrument on MRO collected visible-infrared hyperspectral mapping data (HSP; 180 m/pixel, 262 spectral channels covering 365 to 3937 nm) that covered ∼39% of Mars. Here we present results from a new processing pipeline for these data that produces 5° x 5° hyperspectral mapping tiled mosaics that overlap the coverage of recently released multispectral map tile products (version 4 Multispectral Reduced Data Records, MRDRs; 180 m/pixel, 72 spectral channels). These data enable regional investigations into compositional variations that require high spectral resolution or wavelengths not included in MRDRs. In addition to standard processing techniques available in the CRISM Analysis Toolkit (CAT), the pipeline includes a new correction for systematic discrepancies in radiometric calibration between CRISM observing modes, an improved filtering algorithm to remediate noise, and a technique to correct for differences in radiometry among data strips that arise from differences in photometric and atmospheric conditions. Demonstration hyperspectral mapping tiles covering the Mawrth Vallis region were developed and compared with MRDRs and high spatial resolution hyperspectral targeted observations. The new processing pipeline shows an improvement in data quality over standard processing using CAT utilities. Compared to targeted observations (18 or 36 m/pixel, 545 spectral channels), hyperspectral mapping tile mosaics reveal compositional information across a much greater spatial extent at the expense of 5–10 times coarser spatial resolution. In addition, the hyperspectral mapping tile mosaics reveal greater compositional detail in both the spatial and spectral dimensions compared to MRDRs, but with sparser spatial coverage. Sample hyperspectral mapping tile mosaics over the Mawrth Vallis region reveal hydrated silica, Al-bearing smectite, Fe/Mg-bearing smectite, and mixed clays, consistent with compositions previously reported in the literature.

^1,2Piers Koefoed,³Jean-Alix Barrat,^1,4Olga Pravdivtseva,⁵Conel M. O’D. Alexander,^1,2Katharina Lodders,^1,4Ryan Ogliore,^1,2Kun Wang 王昆
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2023.07.025]
¹McDonnell Center for the Space Sciences, Washington University in St. Louis, St. Louis, Missouri, 63130, USA
²Department of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, Missouri, 63130, USA
³Institut Universitaire Européen de la Mer, Université de Bretagne Occidentale, CNRS UMS 3113, F-29280 Plouzané, France
⁴Department of Physics, Washington University in St. Louis, St. Louis, Missouri, 63130, USA
⁵Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC 20015, USA
Copyright Elsevier

The isotopic analysis of moderately volatile elements such as K have gained significant interest in recent years as they possess the potential to help us better understand solar system formation. Even so, the precise K isotopic composition of CI chondrites, the most chemically primitive chondrite, has remained elusive. As the K elemental composition of CI chondrites matches well with the solar photosphere, it is possible that their K isotopic composition represents the solar system initial value. Here, we investigate the CI chondrite K isotopic composition in order to determine the precise CI chondrite, and thus possibly solar system initial, δ41K value. In addition, we investigate the K isotope compositions of several other chondrite groups, evaluate all available chondrite K isotope data together, and use these data along with data from a range of other isotope systems to assess if nucleosynthetic variations, volatility related processes, or parent body processes can best explain the range of isotope variations. The δ41K composition of all nine CI chondrite pieces analyzed in this study show limited variation, ranging from −0.29‰ to −0.17‰. When combined with the previous CI analysis, an overall mean CI δ41K value of −0.21 ± 0.05‰ (2SE) is obtained. This K isotope composition is distinct from the Bulk Silicate Earth value of −0.43 ± 0.17‰ (2SD), heavier than almost all other chondrite groups, and may represent the solar system initial K isotope composition. When comparing all chondrites broadly, ordinary chondrites show the lightest mean K isotope composition of −0.76 ± 0.06‰ (H = −0.71 ± 0.12‰, L = −0.77 ± 0.04‰, LL = −0.81 ± 0.12‰), enstatite chondrites the middle composition of −0.39 ± 0.11‰ (EH = −0.34 ± 0.05‰, EL = −0.45 ± 0.20‰), and carbonaceous chondrites the heaviest composition of −0.31 ± 0.08‰. For the carbonaceous chondrite groups CK (−0.42 ± 0.11‰), CR (−0.46 ± 0.05‰), and CV (−0.38 ± 0.07‰) chondrites show lighter δ41K compositions compared to CO (−0.20 ± 0.10‰), CM (−0.23 ± 0.11‰), and CI (−0.21 ± 0.05‰) chondrites. When these K isotope group averages are compared against the averages for other mass-dependent moderately volatile element isotope systems (δ87Rb, δ66Zn, δ71Ga, δ128Te) and mass-independent isotope systems (ε54Cr, ε64Ni, ε50Ti, Δ17O, ε40K, and ε66Zn,), a range of correlations are observed. Across all chondrite groups δ41K shows correlations with δ87Rb, δ66Zn, and δ71Ga, and correlations with ε54Cr, ε64Ni, ε50Ti, ε40K, and ε66Zn. When comparing the CCs only, correlations are observed between δ41K and all four of the other moderately volatile elements assessed, while the mass-independent isotope systems show no strong correlations. Regarding the K isotope variations, these observations, along with other textural and chemical data, can be best explained by inherited isotopic variations form different precursor reservoirs (the cause of which is difficult to conclusively determine, though most likely related to the NC-CC dichotomy), and volatility related fractionation processes for the carbonaceous chondrite groups (most likely due to component mixing).

¹Thomas S. Kruijer,¹Lars E. Borg,¹William S. Cassata,¹Josh Wimpenny,¹Greg A. Brennecka,^2,3Charles K. Shearer,²Steven B. Simon
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2023.07.026]
¹Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, 7000 East Avenue (L-231), Livermore, CA 94550, USA
²Institute of Meteoritics, University of New Mexico, Albuquerque, NM 87131, USA
³Lunar and Planetary Institute, Houston, TX
Copyright Elsevier

Alkali-suite rocks constitute one of three major suites of lunar crustal rocks. As such, constraining their formation timescales and petrogenesis is important for understanding the earliest magmatic history of the Moon. However, the magmatic history of alkali-suite rocks is partly obscured by superimposed effects of major basin-forming impact events on the lunar nearside. Consequently, unambiguous crystallization ages of samples from this suite of rocks have not been determined. The aim of this study is to better understand the petrogenetic history of the alkali-suite and the potential superimposed effects of impact metamorphism by determining Sm-Nd, Rb-Sr, and 40Ar/39Ar ages for an alkali anorthosite clast from Apollo 14 lithic breccia 14304 termed clast “b”. The new chronologic measurements of clast “b” yield concordant Sm-Nd, Rb-Sr, and 40Ar/39Ar ages of 3947±13 Ma, 3975±34 Ma, and 3937±37 Ma respectively, resulting in a weighted mean age of 3949±11 Ma. This age is not interpreted to date an igneous event related to production of the lunar highlands crust and instead the chronology and petrography of clast “b” are most readily explained by an impact event at ∼3.95 Ga that caused near-complete isotopic re-equilibration of the Sm-Nd, Rb-Sr, and 40Ar/39Ar chronometers. The weighted mean age of 3949±11 Ma of clast “b” is several hundred Ma younger than 4.3-4.4 Ga ages typically determined for samples of other crustal rock suites but in very good agreement with independent estimates for the formation of Imbrium basin ejecta and other marginally older impact events which are thought to have been sampled at the Apollo 14 landing site. Thus, although petrologic and geochemical examination suggest that clast “b” is a pristine igneous clast, its age likely records an impact event at the Apollo 14 landing site. Whereas the various determined ages of clast “b” do not reflect the timescales of alkali-suite magmatism, the relatively low initial Sr and Nd isotopic compositions of clast “b” indicate that its protolith evolved with very low 147Sm/144Nd and 87Rb/86Sr that are distinct from estimates for urKREEP but similar to that of lunar plagioclase. This implies that the igneous protolith of clast “b” derived from a plagioclase-dominated KREEP-rich source that must have formed after the formation of the urKREEP source at ∼4.35 Ga but well before the impact event recorded by clast “b” at ∼3.95 Ga.

¹Don R. Baker,^2,3Sara Callegaro,⁴Andrea Marzoli,⁵Angelo De Min,⁶Kalotina Geraki,⁷Martin J. Whitehouse,^2,3Agata M. Krzesinska,⁸Anna Maria Fioretti
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2023.08.007]
¹McGill University, Department of Earth and Planetary Sciences, Montréal, Quebec, Canada
²Centre for Earth Evolution and Dynamics (CEED), University of Oslo, Sem Sælands vei 2A N-0371 Oslo, Norway
³Centre for Planetary Habitability (PHAB), University of Oslo, Sem Sælands vei 2A, N-0371 Oslo, Norway
⁴University of Padova, Department of Land, Environment, Agriculture and Forestry, Legnaro, Italy
⁵Department of Mathematics and Geoscience, University of Trieste, via Weiss 2, 34128 Trieste, Italy
⁶Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, U.K
⁷Swedish Museum of Natural History, Stockholm, Sweden
⁸Instituto di Scienze Polari CNR, Padova Italy
Copyright Elsevier

The volatile concentrations of the martian mantle and martian magmas remain important questions due to their role in petrogenesis and planetary habitability. The sulfur and chlorine concentrations, and their spatial distribution, in clinopyroxenes from nakhlites MIL 03346, Nakhla, and NWA 998 were measured to provide insight into these volatiles in the parental melts and source regions of nakhlites, and to constrain the evolution of the nakhlite melts. Sulfur and chlorine in four clinopyroxene crystals from MIL 03346, four from Nakhla, and five from NWA 998 were measured in crystal cores and rims by synchrotron X-ray fluorescence using beamline I18 at the Diamond Light Source. Portions of two crystals from MIL 03346 and one from Nakhla were mapped for S and Cl; a few reconnaissance analyses of Cl and F in MIL 03346 and Nakhla were made by ion microprobe. Clinopyroxene cores in Nakhla and NWA 998 contain ∼ 10 ppm S, ∼ 10 ppm Cl and ∼ 74 ppm F (only Nakhla analyzed), whereas the cores of MIL 03346 contain ∼ 10 ppm S, ∼ 5 ppm Cl and ∼ 53 ppm F.

Using the volatile concentrations in the cores combined with previously determined partition coefficients we calculate that these clinopyroxenes crystallized from evolved basaltic melts containing ∼ 500 ppm S, ∼ 500 to 1900 ppm Cl, and 160 to 420 ppm F. These evolved melts can be used to calculate primitive melts in equilibrium with martian peridotite and the concentrations of S, Cl and F in the mantle source region of the nakhlite melts. Depending upon the extent of melting (5 to 30 %) necessary to produce the primary melts associated with nakhlites, our calculations indicate that the nakhlite source region has a S concentration between 20 (5 % melting) to 120 ppm (30 % melting), Cl between 16 to 97 ppm, and F between 14 to 48 ppm. These concentrations in the nakhlite magma source region are similar to previous estimates for the martian mantle; our calculated source region concentrations of F and Cl agree best with previous estimates if the martian mantle undergoes 10 to 20% melting to produce primary magmas that evolve to be parental to nakhlites. However, our maximum estimated sulfur concentration of the source (calculated for 30 % melting) is near previous minimum estimates for the martian mantle, suggesting the possibility that the nakhlite source region is depleted in sulfur relative to much of Mars’ mantle.

Mapping the spatial distribution of volatiles in three clinopyroxene crystals demonstrates that S and Cl concentrations of the evolving melts changed significantly from the core to the rim, particularly those in MIL 03346. Increasing S and Cl concentrations between the core and rim of MIL 03346 crystals are attributed to incorporation of additional volatiles through assimilation, but the Nakhla crystal shows no such evidence. However, concentrations of Cl and S at some outer crystal rims of one MIL 03346 crystal decrease, most probably due to volatile degassing during the final stages of clinopyroxene growth.

^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.