¹S.R.Jacob et al., (>10)
Journal of Geophysical Research (Planets) Link to Article [https://doi.org/10.1029/2019JE006290]
¹Arizona State University
Published by arrangement with John Wiley & Sons

During 2018 and 2019, the Mars Science Laboratory Curiosity rover investigated the chemistry, morphology, and stratigraphy of Vera Rubin ridge (VRR). Using orbital data from the Compact Reconnaissance Imaging Spectrometer for Mars, scientists attributed the strong 860 nm signal associated with VRR to the presence of red crystalline hematite. However, Mastcam multispectral data and CheMin X‐ray diffraction (XRD) measurements show that the depth of the 860 nm absorption is negatively correlated with the abundance of red crystalline hematite, suggesting other mineralogical or physical parameters are also controlling the 860 nm absorption. Here, we examine Mastcam and ChemCam passive reflectance spectra from VRR and other locations to link the depth, position, and presence or absence of iron‐related mineralogic absorption features to the XRD‐derived rock mineralogy. Correlating CheMin mineralogy to spectral parameters showed that the ~860 nm absorption has a strong positive correlation with the abundance of ferric phyllosilicates. New laboratory reflectance measurements of powdered mineral mixtures can reproduce trends found in Gale crater. We hypothesize that variations in the 860 nm absorption feature in Mastcam and ChemCam observations of VRR materials is a result of three factors: (1) variations in ferric phyllosilicate abundance due to its ~800‐1000 nm absorption; (2) variations in clinopyroxene abundance because of its band maximum at ~860 nm; and (3) the presence of red crystalline hematite because of its absorption centered at 860 nm. We also show that relatively small changes in Ca‐sulfate abundance is one potential cause of the erosional resistance and geomorphic expression of VRR.

¹J.L’Haridon et al. (>10)
Journal of Geophysical Research (Planets) Link to Article [https://doi.org/10.1029/2019JE006299]
¹Laboratoire de Planétologie et Géodynamique, UMR6112, CNRS, Univ Nantes, Univ Angers, Nantes, France
Published by arrangement with John Wiley & Sons

The Curiosity rover investigated a topographic structure known as Vera Rubin ridge, associated with a hematite signature in orbital spectra. There, Curiosity encountered mudstones interpreted as lacustrine deposits, conformably overlying the 300 m‐thick underlying sedimentary rocks of the Murray formation at the base of Mount Sharp. While the presence of hematite (α‐Fe2O3) was confirmed in‐situ by both Mastcam and ChemCam spectral observations and by the CheMin instrument, neither ChemCam nor APXS observed any significant increase in FeOT (total iron oxide) abundances compared to the rest of the Murray formation. Instead, Curiosity discovered dark‐toned diagenetic features displaying anomalously high FeOT abundances, commonly observed in association with light‐toned Ca‐sulfate veins but also as crystal pseudomorphs in the host rock. These iron‐rich diagenetic features are predominantly observed in “grey” outcrops on the upper part of the ridge, which lack the telltale ferric signature of other Vera Rubin ridge outcrops. Their composition is consistent with anhydrous Fe‐oxide, as the enrichment in iron is not associated with enrichment in any other elements, nor with detections of volatiles. The lack of ferric absorption features in the ChemCam reflectance spectra and the hexagonal crystalline structure associated with dark‐toned crystals points toward coarse “grey” hematite. In addition, the host rock adjacent to these features appears bleached and show low‐FeOT content as well as depletion in Mn, indicating mobilization of these redox‐sensitive elements during diagenesis. Thus, groundwater fluid circulations could account for the remobilization of iron and recrystallization as crystalline hematite during diagenesis on Vera Rubin ridge.

¹Katarzyna Łuszczek,²Agata M.Krzesińska
Planetary and Space Science (in Press) Link to Article [https://doi.org/10.1016/j.pss.2020.105092]
¹Wrocław University of Science and Technology, Faculty of Geoengineering, Mining and Geology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
²Centre for Earth Evolution and Dynamics, Department of Geosciences, University of Oslo, Oslo, PO1028 Blindern, 0316 Oslo, Norway

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¹P.M.Thesniya,¹V.J.Rajesh
Planetary and Space Science (in Press) Link to Article [https://doi.org/10.1016/j.pss.2020.105093]
¹Department of Earth and Space Sciences, Indian Institute of Space Science and Technology, Valiamala P.O., Thiruvananthapuram, Kerala, 695547, India

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¹Jonas M.Schneider,¹Christoph Burkhardt,²Yves Marrocchi,³Gregory A.Brennecka,¹Thorsten Kleine
Earth and Planetary Science Letters 551, 116585 Link to Article [https://doi.org/10.1016/j.epsl.2020.116585]
¹Institut für Planetologie, University of Münster, Wilhelm-Klemm-Straße 10, 48149, Germany
²CRPG, CNRS, Université de Lorraine, UMR 7358, Vandoeuvre-lès-Nancy, 54501, France
³Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, United States of America
Copyright Elsevier

Isotopic anomalies in chondrules hold important clues about the dynamics of mixing and transport processes in the solar accretion disk. The meaning of these anomalies is debated and they have been interpreted to indicate either disk-wide transport of chondrules or local heterogeneities of chondrule precursors. However, all previous studies relied on isotopic data for a single element (either Cr, Ti, or O), which does not allow distinguishing between source and precursor signatures as the cause of the chondrules’ isotope anomalies. To overcome this problem, we obtained the first combined O, Ti, and Cr isotope data for individual chondrules from enstatite, ordinary, and carbonaceous chondrites. We find that chondrules from non-carbonaceous (NC) chondrites have relatively homogeneous O, Ti, and Cr, which are similar to the compositions of their host chondrites. By contrast, chondrules from carbonaceous chondrites (CC) have more variable compositions, some of which differ from the host chondrite compositions. Although the compositions of the analyzed CC and NC chondrules may overlap for either Ti, Cr, or O, in multi-isotope space, none of the CC chondrules plot in the compositional field of NC chondrites, and no NC chondrule plots within the field of CC chondrites. As such, our data reveal a fundamental isotopic difference between NC and CC chondrules, which is inconsistent with a disk-wide transport of chondrules across and between the NC and CC reservoirs. Instead, the isotopic variations among CC chondrules reflect local precursor heterogeneities, which most likely result from mixing between NC-like dust and a chemically diverse dust component that was isotopically similar to CAIs and AOAs. The same mixing processes, but on a larger, disk-wide scale, were likely responsible for establishing the distinct isotopic compositions of the NC and CC reservoirs, which represent in inner and outer disk, respectively.

¹Lars E.Borg,¹William S.Cassata,¹Josh Wimpenny,¹Amy M.Gaffney,²Charles K.Shearer
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2020.09.013]
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
Copyright Elsevier

Ages determined for magnesian and ferroan anorthosite crustal rock suites overlap, suggesting they formed contemporaneously about 4.3 to 4.5 Ga. A notable exception is the Sm-Nd age previously determined on Mg-suite gabbronorite 67667 which is at least 100 Ma younger than the youngest ferroan anorthosite. New chronologic measurements of 67667 presented here yield concordant Sm-Nd and Rb-Sr mineral isochron ages of 4349 ± 31 Ma and 4368 ± 67 Ma, suggesting the samples is older than previous estimates. Furthermore, a whole rock Sm-Nd isochron of Mg-suite rocks from the Apollo 14, 15, 16, and 17 landing sites yields an age of 4348 ± 25 Ma, indicating that Mg-suite magmatism was widespread and roughly contemporaneous on the lunar nearside. Analysis of Sm-Nd internal isochron ages confirms that Mg-suite magmatism was restricted to a period between about 4.33 and 4.35 Ga at the Apollo 14, 15, 16, and 17 landing sites and was synchronous with magmatism at the Apollo 16 site associated with the ferroan anorthosite suite between 4.35 and 4.37 Ga. Magnesian- and ferroan anorthosite suite rocks with ages younger than ∼4.33 Ga appear to have experienced slow cooling in the deep lunar interior, so that the ages record when the samples cooled below the closure temperature of the Sm-Nd isotopic system and not the time they crystallized.

The ages determined for Mg-suite and ferroan anorthosite suite rocks are concordant with the age determined for the formation of urKREEP of 4350 ± 34 Ma using the Sm-Nd isotopic systematics of 67667 and measurements completed on norite 78238, troctolite 76535, KREEP basalt 15386, and gabbronorite NWA 773. Crystallization ages of Mg-suite and FAS are also concordant with the average of 146Sm-142Nd ages previously determined for the formation of the mare basalt source region of 4333 ± 30 Ma. The similarity of ages for Mg-suite magmatism, ferroan anorthosite suite magmatism, urKREEP formation, and formation of the mare basalt source regions implies the processes that produced these rocks were petrogenetically linked. It also implies that both early-stage and late-stage lunar magma ocean cumulates formed over a relatively short duration of <40 Ma. Late and somewhat rapid solidification of a lunar magma ocean can account for the concordance of ferroan anorthosite suite rocks, urKREEP, and the mare basalt source regions. However, the major and trace element compositions of Mg-suite magmas preclude them from being a primary differentiation product of the lunar magma ocean. Instead, the Mg-suite could be produced as a result of mixing of magma ocean solidification products during density driven overturn occurring immediately after, or perhaps during, solidification of the lunar magma ocean. This scenario not only accounts for the chronology of the various rock suites, but is consistent with the petrogenesis of the Mg-suite that involves the interaction between pre-existing Mg-rich, plagioclase-rich, and urKREEP-rich cumulates of the magma ocean.

^1,2M.Konstantinidis,¹E.A.Lalla,¹M.G.Daly,³G.Lopez-Reyes,^4,5J.M.Stromberg,⁶K.Cote,⁵E.A.Cloutis
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2020.114113]
¹Centre for Research in Earth and Space Science, York University, 4700 Keele St., Toronto M3J 1P3, Canada
²Department of Mathematics and Statistics, York University, 4700 Keele St., Toronto M3J 1P3, Canada
³Unidad Asociada Universidad de Valladolid-CSIC-CAB, C/Francisco Valles 8, 47151 Boecillo, Valladolid, Spain
⁴CSIRO Mineral Resources, 26 Dick Perry Ave, Kensington, WA 6151, Australia
⁵Department of Geography, University of Winnipeg, 515 Portage Ave, Winnipeg, Manitoba R3B 2E9, Canada
⁶Department of Physics, University of Toronto, 60 St George St, Toronto, ON M5S 1A7, Canada
Copyright Elsevier

As space agencies plan for the continuous deployment of rovers and landers to planetary bodies such as the Moon and Mars, an in-depth, quantitative, and qualitative understanding of the observations is essential. One objective of planetary exploration focuses on planetary geochemistry and biochemistry with an emphasis on the search for possible biosignatures and related minerals. To this end, we present the elemental quantification of samples from the CanMars analogue sample return mission conducted in Hanksville, UT, USA. Measurements were carried out in a laboratory at York University, Canada, using the Laser-induced Breakdown Spectroscopy Raman Sensor (LiRS) instrument- a breadboard for future space concept. A linear Mixture Model (LMM) was used to quantify the abundance of major elements of 10 samples from the resulting Laser-induced Breakdown Spectroscopy LIBS spectra with a calibration set based on the sample mineralogy. We assess the quantification achieved by LiRS and the LMM by error analysis, which resulted in root mean squared error, absolute error, and percentage relative error of less than 1.299 %  ± 0.114% (wt%), 0.959 ± 0.010 (wt%), and 9.613 %  ± 1.914% (of wt%), respectively. The results in question suggest that by complementing information obtained from various sources such as Raman spectroscopy, X-ray diffraction, and Reflectance spectroscopy, the quantification of LIBS may be significantly improved, from which subsequent geochemical inferences may be made. Within the scope of the CanMars analogue mission, these results show an advancement over past results with possible implications for ongoing and future sample return missions such as the OSIRIS-REx and the Mars2020 Perseverance Rover.

¹W.H.Farrand,²J.W.Rice,²F.C.Chuang,³A.D.Rogers
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2020.114111]
¹Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301, USA
²Planetary Science Institute, 1700 East Ft. Lowell, Suite 106, Tucson, AZ 85719, USA
³Stony Brook University, Department of Geoscience, 255 ESS Building, Stony Brook, NY 11794, USA
Copyright Elsevier

Small-scale domes with circumferential aprons and concentric aureoles in western Arcadia Planitia (34–41°N, 167–179°E) near Tyndall crater were examined using a suite of datasets including CRISM, THEMIS IR, HiRISE, and CTX. Previous studies based primarily on photogeologic evidence suggested that these domes were analogous to terrestrial felsic cryptodomes to extrusive lava domes. The domes have also been examined using CRISM visible/near infrared to short-wave infrared (VNIR-SWIR) reflectance spectra which indicated the presence of ferrous silicate minerals in association with the domes. This study presents further CRISM spectral evidence for 1) high-Ca pyroxene and glass mixtures with, or possibly without, the presence of olivine on the flanks of some domes, 2) 1.3 μm band absorption features consistent with an Fe-bearing plagioclase or possibly a Fe-rich alkali feldspar in more limited occurrences at the base of some domes, 3) spectral convexity between 3.4 and 3.9 μm associated with rocky, light-toned portions on top of some domes which is attributed to the presence of alkali-rich plagioclase or alkali feldspars. New morphologic observations include a possible cinder cone and arcs of light-toned, “brain terrain” material on the pole-facing upper margins of some aprons which, in combination with ice-associated “brain terrain” on light-toned outer aureoles suggests an association with ice. The morphology of an assortment of domes and association with alkali feldspars suggests they represent a continuum from intrusive cryptodomes to flat extrusive domes, potentially of felsic composition although formation from viscous alkali-rich mafic magmas is not precluded.

¹Huimin Shao,¹Hiroshi Isobe,²Bingkui Miao
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13563]
¹Department of Earth and Environmental Sciences, Faculty of Advanced Science and Technology, Kumamoto University, Kumamoto, 8608555 Japan
²Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration, Guilin University of Technology, Guilin, 541004 China
Published by arrangement with John Wiley & Sons

The chemical composition and texture of cosmic spherules are influenced by atmospheric conditions and the characteristics of their parent interplanetary particles. The objective of this study was to reproduce I‐type cosmic spherules, which consist mainly of Fe oxide and Fe‐Ni metal, and compare their textural characteristics with those of natural I‐type cosmic spherules. Thus, a series of rapid heating and quenching experiments were performed on free falling iron meteorite powders obtained from Canyon Diablo, in the United States. The experiments were conducted using a high‐temperature furnace with controlled gas flow rates at oxygen fugacities of FMQ + 2.4, FMQ, and FMQ − 2.5 log unit. The resulting Fe‐Ni metal and oxide phases showed the nonequilibrium state of the melted spherules formed during quenching. Two types of magnetite crystals in different orientations were found in iron oxide. As temperatures decreased, the molten metal was oxidized to form immiscible molten iron oxide that then covered the former. As the oxide melt increased at the expense of metal, magnetite began to crystallize from the iron oxide melt, as the liquidus phase, either on the surface or within the melt phase. The characteristics of the run products obtained under different oxygen fugacities were similar to those of natural I‐type cosmic spherules, which have textures and compositions that may contain information regarding the oxygen content of the upper atmosphere. Our study suggests that CO2‐bearing molecules in the atmosphere could form iron oxide with a texture similar to natural I‐type cosmic spherules. During this process, rapid crystallization of magnetite plays an important role in texture formation in disequilibrium states.

¹Andreas Morlok,¹Iris Weber,¹Aleksandra N. Stojic,²Martin Sohn,¹Addi Bischoff,³Dayl Martin,¹Harald Hiesinger,⁴Joern Helbert
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13568]
¹Institut für Planetologie, Westfälische Wilhelms Universität, Münster, Wilhelm‐Klemm‐Str. 10, Münster, 48149 Germany
²Hochschule Emden/Leer, Constantiaplatz 4, Emden, 26723 Germany
³European Space Agency, Fermi Avenue, Harwell Campus, Didcot, Oxfordshire, OX11 0FD UK
⁴Institute for Planetary Research, DLR, Rutherfordstrasse 2, Berlin, 12489 Germany
Published by arrangement with John Wiley & Sons

Aubrites Peña Blanca Spring and Norton County were studied in the mid‐infrared reflectance as part of a database for the MERTIS (Mercury Radiometer and Thermal Infrared Spectrometer) instrument on the ESA/JAXA BepiColombo mission to Mercury. Spectra of bulk powder size fractions from Peña Blanca Spring show enstatite Reststrahlen bands (RB) at 9 µm, 9.3 µm, 9.9 µm, 10.4 µm, and 11.6 µm. The transparency feature (TF) is at 12.7 µm, the Christiansen feature (CF) at 8.1–8.4 µm. Micro‐FTIR of spots with enstatite composition in Norton County and Peña Blanca Spring shows four types: Types I and II are similar to the bulk powder spectra but vary in band shape and probably display axis orientation. Type III has characteristic strong RB at 9.2 µm, 10.4 µm, and 10.5 µm, and at 11.3 µm. Type IV is characterized by a strong RB at 10.8−11.1 µm. Types III and IV could show signs of incipient shock metamorphism. Bulk results of this study confirm earlier spectral studies of aubrites that indicate a high degree of homogeneity and probably make the results of this study representative for spectral studies of an aubrite parent body. Spectral types I and II occur in all mineralogical settings (mineral clasts, matrix, melt, fragments in melt vein), while spectral type III was only observed among the clasts, and type IV in the melt. Comparison with surface spectra of Mercury does not obtain a suitable fit, only type IV spectra from quenched impact glass show similarity, in particular the 11 µm feature. Results of this study will be available upon request or via the IRIS database (Münster) and the Berlin Emissivity Database (BED).