¹Bruno Reynard,²Christophe Sotin
Earth and Planetary Science Letters 612, 118172 Link to Article [https://doi.org/10.1016/j.epsl.2023.118172]
¹Univ Lyon, ENS Lyon, UCB Lyon 1, Univ St-Etienne, CNRS, Laboratoire de Géologie de Lyon, 69007 Lyon, France
²Laboratoire de Planétologie et Géosciences, Nantes Université, Univ Angers, Le Mans Université, CNRS, UMR 6112, F-44000 Nantes, France
Copyright Elsevier

Density and moment of inertia of icy moons and dwarf planets suggest the presence of a low-density carbonaceous component in their rocky cores. This hypothesis was tested using inner density structure and thermal models. Rocky core densities in dwarf planets and icy moons are found to consist of a mixture of chondritic silicate-sulfide rocks and carbonaceous matter. Carbonaceous matter was originally mixed with ice in a rock-free precursor. In a homogeneous accretion scenario where these components are mixed in solar proportions, ices then differentiated from the carbon-rich refractory core, while hydration of silicates could take place. Thermal models taking into account the presence of carbonaceous matter suggest that originally hydrated silicates are only partially dehydrated in the refractory cores of most moons. Viable scenarios point to a difference in formation or evolution between Ganymede and Titan in spite of their similar size and mass. Fully dehydrated mineralogies, inferred in Europa and possibly the densest dwarf planet Eris, require heterogeneous accretion near the water snow line of the solar or circumplanetary nebula. Progressive gas release from slowly warming carbonaceous matter-rich cores may sustain up to present-day the replenishment of ice-oceanic layers in organics and volatiles. It accounts for the observation of nitrogen, light hydrocarbons and complex organic molecules at the surface, in the atmospheres, or in plumes emanating from moons and dwarf planets. The formation of large carbon-rich bodies in the outer solar system suggests that carbon-rich planets could form at the outskirts of extrasolar systems.

¹Xie, Xiande,²Gu, Xiangping
Acta Geochimica 42, 183 – 194 Link to Article [DOI 10.1007/s11631-023-00594-x]
¹Key Laboratory of Mineralogy and Metallogeny / Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China
²School of Geosciences and Info-Physics, Central South University, Changsha, 410083, China

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

¹Tominaga, Takahiro,²Yamaguchi, Naoya,²Sawahata, Hikaru,²Ishii, Fumiyuki
Japanese Journal of Applied Physics 62, SD1019 Link to Article [DOI 10.35848/1347-4065/acaca6]
¹Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan
²Nanomaterials Research Institute (NanoMaRi), Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

¹Nascimento-Dias, Bruno Leonardo,²Alvarenga, Maria Clara Ferreira,³Da Conceição Ben-To, Carolina,¹Zucolotto, Maria Elizabeth
Boletim Paranaense de Geosciencias 80, 212-225 Open Access Link to Article [DOI 10.5380/GEO.V80I2.88719]
¹Universidade Federal do Rio de Janeiro-UFRJ, Museu Nacional. Quinta da Boa Vista -São Cristóvão, RJ, Rio de Janeiro, 20940-040, Brazil
²Universidade Federal do Rio de Janeiro UFRJ, Observatório do Valongo, Ladeira do Pedro Antônio 43 – Centro RJ, Rio de Janeiro, 20080-090, Brazil
³Universidade Federal do Rio de Janeiro UFRJ, Instituto de Geociências, Av. Athos da Silveira Ramos, 274 – Cidade Universitária – Ilha do Fundão RJ, Rio de Janeiro, 21941-916, Brazil

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

¹Dai W.,¹ F.,¹Fang L.,¹Siebert J.
Geochemical Research Letters 24, 33-37 Open Access Link to Article [DOI 10.7185/geochemlet.2302]
¹Universite Paris Cité, Institut de Physique du Globe de Paris, CNRS, 1 rue Jussieu, Paris, 75005, France

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

¹Galuskin, Evgeny,¹Galuskina, Irina O.,²Kamenetsky, Vadim,³Vapnik, Yevgeny,⁴Kusz, Joachim,¹Zieliński, Grzegorz
Lithosphere (in Press) Open Access Link to Article [DOI 10.2113/2022/8127747]
¹Faculty of Natural Sciences, Institute of Earth Sciences, University of Silesia, Poland
²Institute of Experimental Mineralogy RAS, Chernogolovka, 142432, Russian Federation
³Department of Geological and Environmental Sciences, Ben-Gurion University of the Negev, PO Box 653, Beer-Sheva, 84105, Israel
⁴Faculty of Science and Technology, University of Silesia, ul. 75. Pułku Piechoty 1, Chorzów, 41-500, Poland
⁵Polish Geological Institute-National Research Institute, Rakowiecka 4, Warsaw, 00-975, Poland

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

¹Yuan, Jiangyan,¹Huang, Hao,^1,2Chen, Yi,³Yang, Wei,³Tian, Hengci,³Zhang, Di,³Zhang, Huijuan
ACS Earth and Space Chemistry 7, 370 – 378 Link to Article [DOI10.1021/acsearthspacechem.2c00260]
¹State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China
²College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
³Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

¹Camille R. Butkus,²Alexandra O. Warren,²Edwin S. Kite,^3,4Santiago Torres,^3,4Smadar Naoz,⁵Jennifer B. Glass
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2023.115580]
¹School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, USA
²Department of the Geophysical Sciences, University of Chicago, Chicago, IL, USA
³Department of Physics & Astronomy, University of California Los Angeles, Los Angeles, CA, USA
⁴Mani L. Bhaumik Institute for Theoretical Physics, Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, CA, USA
⁵School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA
Copyright Elsevier

Methane is a promising gaseous biosignature on rocky exoplanets, given a suitable context. Establishing the robustness of methane biosignatures on rocky exoplanets requires assessing potential “false positive” production pathways that could yield large fluxes of methane of abiotic origin. Here we modeled the flux of abiotic methane production from graphite hydrogenation on the surface of Mercury, where a relatively carbon-rich crust and bombardment by solar protons might favor this reaction. We calculated negligible methane flux from this abiotic reaction compared to biological methane flux on Earth. Graphite hydrogenation would only be expected to yield significant methane fluxes on exoplanets with high temperatures and ion fluxes that would preclude habitability for life as we know it. Thus, graphite hydrogenation by stellar wind can likely be ruled out as a potential “false positive” methane biosignature source.

¹Dominik Talla,¹Gerald Giester,¹Manfred Wildner
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2023.115583]
¹Institut für Mineralogie und Kristallographie, Universität Wien, Josef-Holaubek-Platz 2, 1090 Wien, Austria
Copyright Elsevier

The presence and importance of sulfates in our solar system have become common knowledge among the dedicated scientific community, as well as their crucial role in governing the water budget of planets such as Mars. The formation of subsurface oceans and cryovolcanism on icy moons of Jupiter and Saturn owe their existence to melting equilibria influenced by sulfate hydrates in the deeper parts of these celestial bodies. In such a setting, it cannot be ruled out that lower-hydrated sulfates including kieserite, MgSO4·H2O, are also present, given their stability under geologic pressures relevant even down to the lower mantle of the icy satellites. With regard to the composition of the water-soluble fraction in C1 and C2 chondritic meteorites presumed to correspond to that of the rocky cores of the Jovian moons, local kieserite may contain significant amounts of Mn in addition to Ni (and also some Fe). Minor Mn contents are probable even in kieserite occurring on the surface of Mars. Substantial lattice parameter changes and spectral band shifts between kieserite and its isostructural Mn-analogue szmikite, MnSO4·H2O, are well known, nevertheless neither the existence of a potential Mgsingle bondMn solid solution series nor its crystal chemical and spectroscopic behavior has yet been investigated.

This work provides the first evidence for such a continuous solid solution, describes its structural properties, and gives a detailed insight into the position changes of prominent bands in FTIR- and Raman spectra of synthetic samples, as the Mn/Mg ratio increases, with the measurement having been performed both at ambient and low temperatures relevant for Mars and the icy satellites. It reveals that contents of Mn do not cause any significant shift in the H2O stretching vibrational bands, yet influence the position of sulfate-related vibrations much in the same way as the incorporation of other relevant transition metal cations, such as Ni. The contrasting behavior of the ν3 and ν1 stretching vibrations of the H2O molecule in case of Mn- (no shift) and Ni-incorporation (significant shift to lower wavenumber) along with their comparable influence on the position of sulfate bands allow to deduce the chemical composition of kieserite in a ternary Mg–Mn–Ni system based on spectroscopic remote sensing or in situ data from celestial bodies. The assessment of chemical composition from vibrational spectra is facilitated by the observed Vegard-type behavior, where lattice parameters as well as the spectral band positions change along linear trends with increasing substitution of Mg, regardless if by Mn, Fe, or Ni. The observed shift of mainly the H2O stretching vibrations to lower wavenumber values as temperature decreases (in contrast to the bands related to the sulfate group) match thermal behavior observed in other binary solid solutions of sulfate monohydrate phases isostructural with kieserite.

^1,2,3C.K. Shearer,^4,5,6D.P. Moriarty,¹S.B. Simon,⁴N. Petro,^1,2J.J. Papike
Journal Geophysical Research (Planets) Link to Article [https://doi.org/10.1029/2022JE007409]
¹Institute of Meteoritics, University of New Mexico, Albuquerque, NM, 87131 United States
²Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM, 87131 United States
³Lunar and Planetary Institute, Houston, TX, 77058 United States
⁴NASA Goddard Space Flight Center, Greenbelt, MD, 20771 United States
⁵University of Maryland, College Park, MD, 20742 United States
⁶Center for Research and Exploration in Space Science and Technology, College Park, MD, 20742 United States
Published by arrangement with Jon Wiley & Sons

Remote sensing observations have been interpreted to indicate that the Crisium basin-forming event excavated deep crust and upper mantle. Samples from the highlands adjacent to the Crisium basin returned by Luna 20 (L-20) bring a unique perspective for evaluating this concept. The magmatic lithologies returned from the noritic Hilly and Furrowed Terrain (nHFT) by L-20 are coarse-grained feldspar (>300 µm) with inclusions of pyroxene, and a finer-grained norites, troctolites, spinel troctolites, and gabbros (<100 µm). These two suites represent ferroan anorthosites (FANs) and the Mg-suite, respectively. There is limited evidence for mantle or deep crustal material within the nHFT samples. Ultramafic rocks such as dunites and orthopyroxenites are absent, and Mg-rich olivine- and orthopyroxene-bearing-assemblages are derived from magmatic rocks emplaced in the shallow crust. These lithic fragments represent pre-Crisium episodes of magmatism and lunar magma ocean products. The lack of deep lithologies at the L-20 site seems contradictory to excavation models for Crisium. Mineralogical-chemical differences suggest a higher FAN component in the rim and that this represents FANs excavated from the deep lunar crust. If it exists, the Mg-rich olivine previously identified within the Crisium rim is most likely related to deep, complementary versions of the Mg-suite rocks from L-20. The material associated with the Crisium basin is not derived from the lunar mantle but represents crustal lithologies from the shallow to deep crust, a substantial mantle component may have been incorporated into the Crisium basin impact melt sheet, or that our “Earth-analog” for the lunar upper mantle is incorrect.