^1,2Julia Semprich,¹Justin Filiberto
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13535]
¹Lunar and Planetary Institute, USRA, 3600 Bay Area Blvd., Houston, Texas, 77058 USA
²AstrobiologyOU, School of Environment, Earth and Ecosystem Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA UK
Published by arrangement with John Wiley & Sons

Here, we calculate the mineralogy of the Martian lower crust and upper mantle as a function of pressure and temperature with depth using four bulk compositions (average crust, Gusev basalt, olivine‐phyric shergottite, and primitive average mantle). We then use this mineralogy to extract rock properties such as density and seismic velocities, describe their changes with varying conditions and geotherms, and make predictions for the crust–mantle boundary. Mineralogically, all compositions produce garnet, orthopyroxene, clinopyroxene in varying proportions at high pressures, with differences in minor minerals (spinel, ilmenite, rutile, and/or K‐feldspar). According to our calculations, the average crust and Gusev basalt compositions have the potential to yield higher densities than the average mantle composition, particularly for thicker crusts and/or colder geotherms. Therefore, recycling of the Martian crust into the mantle could occur through the process of crustal delamination, if not kinetically inhibited. However, our results show that, depending on crustal thickness, the crust may not be easily distinguishable from the mantle in seismic properties.

¹Annarita Franza,²Giovanni Pratesi
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13525]
¹Department of Earth Sciences, University of Firenze, Via G. La Pira 4, 50121 Firenze, Italy
²¹INAF‐IAPS, Istituto di Astrofisica e Planetologia Spaziali, Via Fosso del Cavaliere 100, 00133 Roma, Italy
Published by arrangement with John Wiley & Sons

Julius Obsequens was the pseudonym of a Roman historian presumably living in the 4th century ad , whose life is shrouded in mystery. All that is known about Obsequens’s biography is that he was the author of a book entitled Liber Prodigiorum (Book of Prodigies ), a collection of prodigies deduced from Livy’s Ab Urbe Condita Libri (Books from the Founding of the City ). The Liber Prodigiorum covered the period from 190 to 11 bc and gathered a chronological list of portents of various kinds (e.g., births of monstrous animals or men, statues that shed blood, voices from beyond the grave, epidemics, earthquakes, unidentified flying objects). Among these extraordinary reports, chronicles of celestial phenomena were also included. The interdisciplinary approach adopted in this research has clarified the nature of the events described in the text and has enabled the identification of new Italian meteorite falls that are not included in the Meteoritical Bulletin Database.

^1,2Brant M. Jones,¹Aleksandr Aleksandrov,³M. Darby Dyar,⁴Charles A. Hibbitts,^1,2,4Thomas M. Orlando
Journal of Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2019JE006147]
¹School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA
²Center for Space Technology and Research, Georgia Institute of Technology, Atlanta, GA, USA
³Planetary Science Institute, Tucson, AZ, USA
⁴John Hopkins Applied Physics Laboratory, Laurel, MD, USSchool of Physics, Georgia Institute of Technology, Atlanta, GA, USA
Published by arrangement with John Wiley & Sons

Desorption activation energies of chemisorbed water on Apollo lunar Samples 14163 and 10084 were determined by temperature program desorption (TPD) experiments conducted under ultrahigh vacuum conditions. Desorption at the grain/vacuum interface and desorption/transport of water though the porous medium with readsorption were found to reproduce the experimental TPD signal. Signal from the grain/vacuum interface yielded desorption activation energies and site probability distributions. Highland sample 14163 exhibited a broad distribution of binding site energies peaking at 60 kJ mol⁻¹, while mare sample 10084 exhibited a narrower distribution of binding site energies peaking at 65 kJ mol⁻¹. The highland sample adsorbed approximately 30% more water than the more space weathered and mature mare sample, suggesting maturity may not be a good predictor of the degree of molecular water uptake on lunar regolith. Water desorption from the lunar surface over a typical lunar day was simulated with the measured coverage‐dependent activation energies of the mare and highland samples. The resulting desorption profile of water through a lunar temperature cycle is in general agreement with Lunar Reconnaissance Orbiter (LRO) Lyman‐α Mapping Project (LAMP) spacecraft‐based observations of trends for both highland and mare assuming ~1% submonolayer coverage and that photon stimulated desorption is neglected.

¹G. M. Wong,^2,3,4J. M. T. Lewis,^3,4C. A. Knudson,^4,5M. Millan,³A. C. McAdam,³J. L. Eigenbrode,³S. Andrejkovičová,⁶F. Gómez,⁷R. Navarro‐González,¹C. H. House
Journal of Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2019JE006304]
¹Department of Geosciences, Pennsylvania State University, University Park, PA
²Department of Physics and Astronomy, Howard University, Washington, D.C.
³Planetary Environments Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD
⁴Center for Research and Exploration in Space Science and Technology, NASA GSFC, Greenbelt, MD
⁵Department of Biology, Georgetown University, Washington, DC
⁶Centro de Astrobiologia (CSIC‐INTA), Torrejón de Ardoz, Madrid, Spain
⁷Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de México, Mexico
Published by arrangement with John Wiley & Sons

The Mars Science Laboratory mission investigated Vera Rubin ridge, which bears spectral indications of elevated amounts of hematite and has been hypothesized as having a complex diagenetic history. Martian samples, including three drilled samples from the ridge, were analyzed by the Sample Analysis at Mars instrument suite via evolved gas analysis‐mass spectrometry (EGA‐MS). Here, we report new EGA‐MS data from Martian samples and describe laboratory analogue experiments. Analyses of laboratory analogues help determine the presence of reduced sulfur in Martian solid samples, which could have supported potential microbial life. We used evolved carbonyl sulfide (COS) and carbon disulfide (CS₂) to identify Martian samples likely to contain reduced sulfur by applying a quadratic discriminant analysis. While we report results for 24 Martian samples, we focus on Vera Rubin ridge samples and select others for comparison. Our results suggest the presence of reduced sulfur in the Jura member of Vera Rubin ridge, which can support various diagenetic history models, including, as discussed in this work, diagenetic alteration initiated by a mildly reducing, sulfite‐containing groundwater.

^1,2D. C. Hickson,³A. L. Boivin,⁴C. A. Tsai,¹M. G. Daly,³R. R. Ghent
Journal of Geophysical Research (Planets) (In Press) Link to Article [https://doi.org/10.1029/2019JE006141]
¹Centre for Research in Earth and Space Science, York University, Toronto, ON, Canada
²Arecibo Observatory, University of Central Florida, PR, USA
³Solar System Exploration Group, Department of Earth Sciences, University of Toronto, Toronto, ON, Canada
⁴Department of Physics, University of Toronto, Toronto, ON, Canada
Published by arrangement with John Wiley & Sons

Planetary radar has provided a growing number of datasets on the inner planets and near‐Earth and main‐belt asteroid populations in the solar system. Physical interpretation of radar data for inference of surface properties requires constraints on the constitutive parameters of the material making up a given surface. In this study, the complex permittivity of seven minerals as a function of frequency and porosity is measured using the coaxial transmission line method to determine the mixing equation that best describes the relationship between the real part of the complex permittivity of single mineral crystals and granular mineral powders. We find the Looyenga‐Landau‐Lifshitz and Bruggeman Symmetric mixing equations to describe our experimental results with the highest accuracy. The variation in the real part of the permittivity of solid mineral crystals between different minerals is shown to depend on the grain density and the chemical composition of the minerals. These mixing relationships are incorporated into an asteroid radar model and used to calculate the porosity in the near‐surface of seven asteroids visited by robotic spacecraft using Earth‐based radar observations. The results of the asteroid radar model support the presence of significant porosity in the boulders on the surface of asteroid 101955 Bennu. This research highlights the ability of radar to measure the porosity on asteroid surfaces and provides theoretical and experimental justification for the inversion of permittivity to bulk density assumed by the asteroid radar model.

¹Amy C. McAdam et al. (>10)
Journal of Geophysical Research (Planets) (In Press) Link to Article [https://doi.org/10.1029/2019JE006309]
¹NASA Goddard Space Flight Center, Greenbelt, MD, USA
Published by arrangement with John Wiley & Sons

Vera Rubin ridge (VRR) is a topographic high within the layers of Mount Sharp, Gale crater, that exhibits a strong hematite spectral signature from orbit. The Mars Science Laboratory Curiosity rover carried out a comprehensive investigation to understand the depositional and diagenetic processes recorded in the rocks of VRR. Sample Analysis at Mars (SAM) evolved gas analyses (EGA) were performed on three samples from the ridge and one from directly beneath the ridge. SAM evolved H2O data suggested the presence of an Fe‐rich dioctahedral smectite, such as nontronite, in the sample from beneath the ridge. H2O data are also consistent with ferripyrophyllite in VRR samples. SAM SO2 data indicated that all samples contained Mg sulfates, and some Fe sulfate. Several volatile detections suggested trace reduced sulfur sources, such as Fe sulfides and/or S‐bearing organic compounds, in two samples while significant O2 and NO evolved from one sample indicated the presence of oxychlorine and nitrate/nitrite salts, respectively. The O2 evolution was the second highest to date and the first observed in ~1200 sols. HCl released from all samples likely resulted, in part, from trace chloride salts. All samples evolved CO2 and CO consistent with oxidized carbon compounds (e.g., oxalates), while some CO2 may result from carbonate. SAM‐derived constraints on the mineralogy and chemistry of VRR materials, in the context of additional mineralogy, geochemistry, and sedimentology information obtained by Curiosity , support a complex diagenetic history that involved fluids of a range of possible salinities, redox characteristics, pHs, and temperatures.

¹Nicole X.Nie,¹Nicolas Dauphas,¹Krysten L.Villalon,²Nan Liu,¹Andy W.Heard,³Richard V.Morris,⁴Stanley A.Mertzman
Earth and Planetary Science Letters 544, 116385 Link to Article [https://doi.org/10.1016/j.epsl.2020.116385]
¹Origins Laboratory, Department of the Geophysical Sciences and Enrico Fermi Institute, The University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637, USA
²Department of Physics, Washington University in St. Louis, St. Louis, MO 63130, USA
³ NASA Johnson Space Center, Houston, TX, 77058, USA
⁴Department of Earth and Environment, Franklin and Marshall College, Lancaster, PA 17604-3003, USA
Copyright Elsevier

We cannot reproduce the abstract of this paper for technical reasons

^1,2Tianqi Xie,^1,2Gordon R. Osinski,^1,2Sean R. Shieh
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13523]
¹Department of Earth Sciences, University of Western Ontario, 1151 Richmond Street, London, Ontario, N6A 5B7 Canada
²Institute for Earth and Space Exploration, University of Western Ontario, 1151 Richmond Street, London, Ontario, N6A 5B7 Canada
Published by arrangement with John Wiley & Sons

Plagioclase feldspar is one of the most abundant minerals on the surface of the Earth, the Moon, and Mars, and is also commonly found in meteorites. Studying shock effects in feldspar thus provides us with fundamental information about impact cratering processes on planetary bodies. In this study, plagioclase from monomict and polymict breccias, impact melt rocks, and shock‐metamorphosed target rocks, from throughout the Mistastin Lake impact structure, Canada, was examined using 514 nm laser Raman spectroscopy. As one of the very few impact structures with anorthosite in the target rocks, the Mistastin Lake impact structure provides a unique opportunity to study shocked plagioclase displaying progressive shock metamorphic features. A series of microscopic features was observed within plagioclase, including twins, needle‐like inclusions, planar features, and alteration. The lack of planar deformation features is notable. Raman spectra of these features suggest that this technique is capable of differentiating and classifying shock features in low to moderately shocked rocks. Caution should be exercised, however, as Raman spectra collected from unshocked plagioclase references with known compositions indicate that peak width and peak ratio of the Raman peaks in lower wave number region (<350 cm−1) and the main signature peaks around 500 cm−1 vary with chemical composition and crystal orientation. Data collected from diaplectic glass suggest that Raman features are efficient in distinguishing crystalline plagioclase and diaplectic glass. We also observed significant variations in the Raman intensities collected from diaplectic glass, which we ascribe to the localized disorder or inhomogeneity of shock pressure and temperature throughout the target.

¹Balz S.Kamber,^2,3Ronny Schoenberg
Earth and Planetary Science Letters 544, 116356 Link to Article [https://doi.org/10.1016/j.epsl.2020.116356]
¹School of Earth and Atmospheric Sciences, Queensland University of Technology, Australia
²Isotope Geochemistry, Department of Geosciences, Eberhard-Karls University of Tuebingen, Germany
³Department of Geology, University of Johannesburg, South Africa
Copyright Elsevier

The retention of moderately volatile elements on the growing Earth remains a major uncertainty in models of terrestrial accretion. Large impactors were the main carriers of accreted material but their mutual energetic collisions and impacts onto the Earth also caused chemical fractionation for which limited experimental data exist. The objective of this work was to study several moderately volatile elements in the third-largest impact basin preserved on Earth at Sudbury, Ontario. We conducted a new chemostratigraphic transect (
) of Zn isotope ratios and concentrations by analysing melt sheet and basin fill samples. The data were compared to common Pb, Cs, Cd and Sb concentration systematics. Within the crystallised melt sheet there are strong trends in the extent of moderately volatile element deficits, Zn isotope composition (
ZnJMC-L from 0.18 to 0.47‰) and initial Pb isotope composition. The combined evidence suggests that these trends reflect footwall contamination of a melt sheet that had experienced evaporative Zn-loss of up to 75–80%. Accounting for plausible isotopic signatures of target rocks, the maximum mass-dependent Zn isotope fractionation ε was 0.29 ± 0.04‰ (1 s.d.), which translates to modest fractionation factors
to 0.99975. This is comparable to melt fallout-glass and fused sands from nuclear detonation sites. We attribute the observed Zn loss and isotope fractionation to the formation of the impact melt. The rapid formation of a solid lid of breccias upon seawater ingress may have prevented stronger evaporative loss and isotope fractionation. Within the crater fill, there is an up-stratigraphy increase in Zn isotope variability (
ZnJMC-L from 0.29 to 1.05‰). Combined with evidence for biogenic reduced C, this suggests sedimentation of authigenic particulates within an enclosed crater sea.

In the melt sheet, the Zn-Pb and Rb-Cs pairs experienced different extents of maximum evaporative loss (Pb up to 98.4% vs. Zn 78%; and Cs ∼90% vs. Rb ∼30%). The relative loss pattern could reflect evaporation from superheated silicate melt at ∼1,450 °C and 1 atm. Loss from super-liquidus melts formed by bolide impacts could have been a significant process shaping the Earth’s volatile and moderately volatile inventory.

^1,2Sheng Gou et al. (>10)
Earth and Planetary Science Letters 544, 116378 Link to Article [https://doi.org/10.1016/j.epsl.2020.116378]
¹State Key Laboratory of Remote Sensing Science, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100101, China
²State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Macau, China
Copyright Elsevier

Chang’e-4 rover discovered a dark greenish and glistening impact melt breccia in a crater during its traverse on the floor of Von Kármán crater within the South Pole Aitken (SPA) basin on the lunar farside. The discovered breccia, being 52 × 16 cm, resembles the lunar impact melt breccia samples 15466 and 70019 that returned by the Apollo missions. It was formed by impact-generated welding, cementing and agglutinating of lunar regolith and breccia. Clods surrounds the breccia-hosting crater were crushed into regolith powders by the rover’s wheels, indicating the regolith may be compacted slightly and becomes blocky and friable. Relative mineral fractions are estimated from the in situ measured spectra by a Hapke model-based unmixing algorithm. Unmixing reveals that plagioclase (PLG, 45 ± 6%) is dominant in the regolith, followed by almost equal fractions of pyroxene (PYX, 7 ± 1%) and olivine (OL, 6 ± 2%), indicating the regolith is likely related to noritic rocks. The regolith measured by Chang’e-4 rover was actually a highly mixture of multiple sources, with ejecta from Finsen crater being primary and possible contributions from Alder crater. Finsen and Alder craters are on the margin of the proposed impact melt pool produced by the SPA basin-forming event. Therefore, the ultimate source of the regolith might originate from a differentiated melt pool or from a suite of igneous rocks.