¹E.Clave et al.(>10)
Journal of Geopyhsical Reearch (Planets)(in Press) Link to Article [https://doi.org/10.1029/2022JE007463]
¹CELIA, Université de Bordeaux, CNRS, CEA, Bordeaux, France
Published by arrangement with John Wiley & Sons

Perseverance explored two geological units on the floor of Jezero Crater over the first 420 Martian days of the Mars2020 mission. These units, the Máaz and Séítah formations, are interpreted to be igneous in origin, with traces of alteration. We report the detection of carbonate phases along the rover traverse based on laser-induced breakdown spectroscopy (LIBS), infrared reflectance spectroscopy (IRS), and time-resolved Raman (TRR) spectroscopy by the SuperCam instrument. Carbonates are identified through direct detection of vibrational modes of CO3 functional groups (IRS and TRR), major oxides content, and ratios of C and O signal intensities (LIBS). In Séítah, the carbonates are consistent with magnesite-siderite solid solutions (Mg# of 0.42-0.70) with low calcium contents (<5 wt.% CaO). They are detected together with olivine in IRS and TRR spectra. LIBS and IRS also indicate a spatial association of the carbonates with clays. Carbonates in Máaz are detected in fewer points, as: (i) siderite (Mg# as low as 0.03); (ii) carbonate-containing coatings, enriched in Mg (Mg# ∼0.82) and spatially associated with different salts. Overall, using conservative criteria, carbonate detections are rare in LIBS (∼30/2000 points), IRS (∼15/2000 points), and TRR (1 /150 points) data. This is best explained by (i) a low carbonate content overall, (ii) small carbonate grains mixed with other phases, (iii) intrinsic complexity of in situ measurements. This is consistent with orbital observations of Jezero crater, and similar to compositions of carbonates previously reported in Martian meteorites. This suggests a limited carbonation of Jezero rocks by locally equilibrated fluids.

¹L.Mandon et al. (>10)
Journal of Geopyhsical Research (Planets)(in Press) Link to Article [https://doi.org/10.1029/2022JE007450]
¹LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, Meudon, France
Published by arrangement with John Wiley & Sons

The Perseverance rover landed in the ancient lakebed of Jezero crater, Mars on February 2021. Here we assess the mineralogy of the rocks, regolith, and dust measured during the first year of the mission on the crater floor, using the visible and near-infrared spectrometer of SuperCam onboard the Perseverance rover. Most of the minerals detected from orbit are present in the bedrock, with olivine-bearing rocks at the bottom of the stratigraphy and high-Ca pyroxene-bearing rocks at the top. This is distinct from the overall low-Ca pyroxene-bearing composition of the watershed of Jezero, and points towards an igneous origin. Alteration mineral phases were detected in most of the rocks analyzed in low proportions, suggesting that aqueous alteration of the crater floor has been spatially widespread, but limited in intensity and/or time. The diverse aqueous mineralogy suggests that the aqueous alteration history of the crater floor consists of at least two stages, to form phyllosilicates and oxyhydroxides, and later sulfates. We interpret their formation in a lake or under deeper serpentinization conditions, and in an evaporative environment, respectively. Spectral similarities of dust with some rock coatings suggest widespread past processes of dust induration under liquid water activity late in the history of Jezero. Analysis of the regolith revealed some local inputs from the surrounding rocks. Relevant to the Mars Sample Return mission, the spectral features exhibited by the rocks sampled on the crater floor are representative of the diversity of spectra measured on the geological units investigated by the rover.

¹Pei Ma,^1,2Hao Zhang,³Yazhou Yang,¹Te Jiang,⁴Daniel Britt,⁵Menghua Zhu
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2023.115608]
¹School of Earth Sciences, China University of Geosciences, Wuhan, China
²CAS Center for Excellence in Comparative Planetology, Hefei, China
³National Space Science Center, Chinese Academy of Sciences, Beijing, China
⁴University of Central Florida, Orlando, FL, USA
⁵State Key Laboratory of Lunar and Planetary Science, Macau University of Science and Technology, Macau
Copyright Elsevier

As a new planetary remote sensing tool, the phase ratio imagery calculates the ratio of images taken at different phase angles and may suppress surface albedo variations and enhance surface texture features. This technique has been used in the study of surface structure of airless bodies such as the Moon and Mercury. To understand the effectiveness of the method, we carried out laboratory phase ratio measurements on eight planetary analog materials including four pure minerals olivine, orthopyroxene, labradorite, ilmenite and four mixtures, the lunar regolith simulant JSC-1A, the lunar highland simulant, the Martian soil simulant, and the CI asteroid simulant, all in two size distributions, 0–45 μm and 90–105 μm. For each sample, the phase ratio A(α1)/A(α2) is obtained by measuring the reflectance at two phase angles α1 and α2 with α1<α2 at two radiation wavelengths, 633 nm and 905 nm. The results show that: (1) The particle size distributions can be differentiated by measuring the phase ratio A(α1)/A(α2), and in order to increase the discriminative power of the particle size distribution, the value of (α1-α2) should be as large as possible. (2) For pure minerals, larger grains have smaller phase ratio values, because larger grains of pure minerals are more forward scattering, leading to larger A(α2) and thus smaller phase ratio. For mixtures with simulated agglutinates that hold minerals together as composite particles, larger grains have higher phase ratios because they are less forward scattering due to multiple internal reflections and hence more absorptions. Since real planetary regoliths are likely dominated by composite particles with agglutinates, it is expected that larger grains would have larger phase ratio values.

^1,2Robert W. Nicklas,¹James M. D. Day,³Zoltán Váci,⁴Minghua Ren,⁵Kathryn G. Gardner-Vandy,⁶Kimberly T. Tait
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2023.04.019]
¹Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, 92093, USA
²Department of Earth and Environmental Sciences, Boston College, Chestnut Hill, MA, 02467, USA
³Department of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, MO, 63130, USA
⁴Department of Geoscience, University of Nevada, Las Vegas, Las Vegas, NV, 89154, USA
⁵Aviation and Space, Oklahoma State University, Stillwater, OK, 74078, USA
⁶Department of Natural History, Royal Ontario Museum, Toronto, ON, M5S 2C6, Canada
Copyright Elsevier

Metal-silicate segregation is one of the most fundamental mechanisms in planetary differentiation, with primitive achondrites offering important constraints on this process. Brachinites and brachinite-like achondrites (BLA) are olivine-dominated primitive achondrites that experienced up to ∼20% partial melt removal under relatively oxidized (ΔIW∼-1) conditions within an initially chondritic parent body and represent residues with inefficient metal-loss. We present bulk rock and in situ lithophile and highly siderophile element (HSE) abundance systematics as well as ¹⁸⁷Re-¹⁸⁷Os data for five olivine-rich primitive achondrites. These new data confirm classification of Reid 013 as a brachinite, three of the samples as BLA (Northwest Africa [NWA] 6874, NWA 7499, and Miller Range 090805), and the final sample as an ungrouped primitive olivine-rich achondrite (NWA 7680). An aliquot of MIL 090805 shows amongst the highest total HSE contents (>35 ppm) and the highest Pt content (∼23 ppm) of any primitive achondrite. Compiled HSE data for brachinites and BLA show correlations between total HSE abundance, Pt enrichment, and average olivine Fo. This correlation can be explained by variable melting (∼10-20%) of an H ordinary chondrite-like protolith, with retention of both Fe-metal and a Pt-rich alloy phase distinct from the observed Fe-metal phases in more depleted residues. Such a Pt-alloy phase is likely stabilized by elevated abundances of the HSE during chondrite melting and the low solubility of HSE in melts. Rhenium-Os isotope data in the studied samples has been modified by recent mobilization of Re during terrestrial weathering, with the limited range of measured ¹⁸⁷Os/¹⁸⁸Os in brachinites and BLA supporting minor fractionation of Re/Os during melting and an ancient (∼4.5 Ga) partial melting event to explain their compositions. These results indicate that models of planetary differentiation should consider the low solubility of Pt in chondrite melts and the potential for alloy formation to modify HSE abundances of silicate mantles.

¹Pierre-Marie Zanetta,^1,2Venkateswara Rao Manga,¹Yao-Jen Chang,²Tarunika Ramprasad,¹Juliane Weber,³John R. Beckett,^1,2Thomas J. Zega
American Mineralogist 108, 881-902 Link to Article [http://www.minsocam.org/msa/ammin/toc/2023/Abstracts/AM108P0881.pdf]
¹Lunar and Planetary Laboratory, The University of Arizona, Tucson, Arizona 85721, U.S.A.
²Materials Science and Engineering, The University of Arizona, Tucson, Arizona 85721, U.S.A.
³Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, U.S.A.
Copyright: The Mineralogical Society of America

Calcium-aluminum-rich inclusions (CAIs) in chondritic meteorites are composed of refractory
minerals thought to be the first solids to have formed in the solar nebula. Among them, hibonite,
nominally CaAl12O19, holds particular interest because it can incorporate significant amounts of Ti
into its crystal structure in both Ti3+ and Ti4+ oxidation states. The relative amounts of these cations
that are incorporated reflect the redox conditions under which the grain formed or last equilibrated and
their measurement can provide insight into the thermodynamic landscape of the early solar nebula.
Here we develop a new method for the quantification of Ti oxidation states using electron energy-loss
spectroscopy (EELS) in an aberration-corrected scanning transmission electron microscope (STEM)
to apply it to hibonite.
Using a series of Ti-bearing oxides, we find that the onset intensity of the Ti L2,3 edge decreases with
increasing Ti-oxidation state, which is corroborated by simulated Ti-oxide spectra using first-principles
density-functional theory. We test the relationship on a set of synthetic hibonite grains with known
Ti4+/ΣTi values and apply the developed method on a hibonite grain from a compact type A inclusion
in the Northwest Africa (NWA) 5028 CR2 carbonaceous chondrite. The STEM-EELS data show that
the chondritic hibonite grain is zoned with a Ti4+/ΣTi ratio ranging from 0.78 ± 0.04 to 0.93 ± 0.04
over a scale of 100 nm between the core and edge of the grain, respectively. The Ti substitution sites
are characterized by experimental and calculated high-angle annular-dark-field (HAADF) images and
atomic-level EEL spectrum imaging. Simulated HAADF images reveal that Ti is distributed between
the M2 and M4 sites while Mg sits on the M3 site. Quantitative energy-dispersive X-ray spectroscopy
shows that this grain is also zoned in Al and Ti. The Mg distribution is not well correlated with that
of Ti and Ti4+/ΣTi at the nanoscale.
The spatial decoupling of the element composition and Ti-oxidation states suggests a multistage
evolution for this hibonite grain. We hypothesize that Ti and Mg were incorporated into the structure
during condensation at high temperature through multiple reactions. Transient heating, presumably
in the solar nebula, adds complexity to the crystal chemistry and potentially redistributed Ti and Mg.
Concurrently, the formation of oxygen vacancies as a result of a reducing gas, led to the reduction of
Ti4+ to Ti3+. The multiple defect reactions occurring in this single hibonite crystal preclude a simple
relationship between the Ti4+/ΣTi and the fO2 of formation. However, moving forward, these measurements are fundamental inputs for modeling of the thermodynamic conditions under which hibonite
formed in the early solar nebula.

¹L. Shestakova,¹A. Serebryanskiy,¹G. Aimanova
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2023.115595]
¹Fesenkov Astrophysical Institute, Obseravtory, 23, Almaty, 050020, Kazakhstan
Copyright Elsevier

We report on the results of the analysis of spectral observations of the asteroid Didymos at the time of impact of the DART mission probe, obtained a few minutes before, directly at the moment, and within a few minutes after the spacecraft hit the surface of the Dimorphos. We found evidence of alkali metal emissions that appeared at the moment and continued for several minutes after the impact. The observation evidence of the appearance of Na, Li and K atoms as a result of the impact of the DART probe on the Dimorphos in a relative amount close to the abundance of these elements in the Solar System are reliably established. We conclude that the main contribution to alkaline emissions is atoms bound to the dust cloud ejected during the impact. This dust cloud is a steady source of alkaline metal atoms. We did not detect the presence of alkaline mater not bound to the dust cloud and moved independently.

¹Matthew A. Nellessen et al. (>10)
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2023.115599]
¹Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM, USA
Copyright Elsevier

Boron has been detected on Mars in calcium-sulfate veins found within clay mineral rich rocks on Mars by the Mars Science Laboratory (MSL) Curiosity rover using Laser Induced Breakdown Spectroscopy (LIBS) analysis. Borates play a vital role in stabilizing ribose on Earth and has been suggested as a key requirement for life. Borate ions readily adsorb to phyllosilicate clay minerals. The discovery of boron on Mars in proximity to phyllosilicate-bearing bedrock may have strong implications for potential past prebiotic conditions on Mars. In this study we generated a suite of clay minerals with adsorbed borate, including both typical terrestrial clay minerals (montmorillonite) and Mars-analog clay minerals (nontronite, saponite, griffithite), to understand controls on borate adsorption and to analyze with LIBS to compare with MSL data. Clay minerals were subjected to mineralogical and chemical analysis before and after adsorption. Adsorption analysis revealed that the Mars analog clay minerals adsorbed less boron than terrestrial counterparts, but within comparable amounts to those detected on Mars and in meteorites. Post-adsorption analysis by X-ray diffraction (XRD) revealed slight changes in the interlayer spacing of many of the clay minerals. Based on the adsorption analysis of the Mars-analog clay minerals, phyllosilicate-bearing bedrock in Gale crater may contain up to 90-110 ppm B. A series of borate-enriched samples were created for analysis of LIBS spectra from ChemCam on the Curiosity rover and SuperCam on the Perseverance Rover. The results of this study may provide insight into martian groundwater geochemistry processes and the mobility of a key molecule connected with life.

^1,2Emmy B. Hughes,¹Martha Gilmore,³Peter E. Martin,⁴Miriam Eleazer
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2023.115597]
¹Department of Earth and Environmental Sciences, Wesleyan University, 265 Church St., Middletown, CT 06438, United States of America
²School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, United States of America
³Department of Geological Sciences, University of Colorado, Boulder
⁴Department of Astronomy, Wesleyan University, Middletown, CT, United States of America
Copyright Elsevier

While much attention has been given to the identification and characterization of single-phase salts on Mars, relatively little has been applied to mixed evaporative assemblages. Given the likely existence of these assemblages on Mars (e.g., basin deposits) and the lack of data on their spectral signatures, here we present an experimental study of multicomponent S and Cl-bearing Mars-relevant brines. We modeled, synthesized and evaporated brines in the laboratory under both martian and terrestrial (P, T, pCO2) environmental conditions, and characterized the resulting precipitates using Visible–Near Infrared (VNIR), Raman spectroscopy, XRD and SEM-EDS. We compared these results to mineral assemblages calculated using the FREZCHEM thermodynamic model. For mixed brines primarily containing Na+, K+, Mg2+, Ca2+, SO42− and Cl−, epsomite (MgSO4•7H2O) and bischofite (MgCl2•6H2O) overwhelm VNIR and Raman spectra, while anhydrous crystalline salts and Na- and K-sulfates are unidentified. Mg-sulfates are identifiable in the VNIR and Raman even at low or no modeled mass abundance in an evaporative assemblage and are often the only clearly identifiable salt. These results imply that regions of Mg-sulfate identification on Mars may have only minor amounts of Mg-sulfate present, and significant amounts of halides or other sulfates may be undetectable. This may be due to a combination of late-stage Mg-sulfate precipitation and non-linear spectral mixing. Raman is more sensitive than VNIR to the identification of Ca-sulfate salts in these mixed assemblages. We predict that high abundances of mixed chloride and sulfate salts species will be identified as the Curiosity Rover continues to explore the Sulfate Unit of Gale Crater, and note that the Perseverance rover offers the first opportunity to identify such mixed assemblages in Jezero Crater with this combination of techniques.

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

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