¹Shao H.,¹Isobe H.,¹Kitahara G.,²Fukui H.,¹Yoshiasa A.
Physics and Chemistry of Minerals 48, 11 Link to Article [DOI 10.1007/s00269-021-01136-8]
¹Department of Earth and Environmental Sciences, Faculty of Advanced Science and Technology, Kumamoto University, Kumamoto, 860-8555, Japan
²Department of Material Science, Graduate School of Material Science, University of Hyogo, Hyogo, 678-1297, Japan

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^1,2Valerie K. Fox et al. (>10)
American Mineralogist 106, 964–982 Link to Article [DOI: https://doi.org/10.2138/am-2020-7419CCBYNCND]
¹California Institute of Technology, 1200 E. California Boulevard, Pasadena, California 91125, U.S.A
²University of Minnesota, John T. Tate Hall, 116 Church Street
SE, Minneapolis, MN 55455-0149, U.S.A.
Copyright: The Mineralogical Society of America

This study demonstrates the synergies and limits of multiple measurement types for the detection
of smectite chemistry and oxidation state on planetary surfaces to infer past geochemical conditions.
Smectite clay minerals are common products of water-rock interactions throughout the solar system,
and their detection and characterization provides important clues about geochemical conditions and past
environments if sufficient information about their composition can be discerned. Here, we synthesize
and report on the spectroscopic properties of a suite of smectite samples that span the intermediate
compositional range between Fe(II), Fe(III), Mg, and Al end-member species using bulk chemical
analyses, X‑ray diffraction, Vis/IR reflectance spectroscopy, UV and green-laser Raman spectroscopy,
and Mössbauer spectroscopy. Our data show that smectite composition and the oxidation state of octahedral Fe can be reliably identified in the near infrared on the basis of combination and fundamental
metal-OH stretching modes between 2.1–2.9 μm, which vary systematically with chemistry. Smectites
dominated by Mg or Fe(III) have spectrally distinct fundamental and combination stretches, whereas
Al-rich and Fe(II)-rich smectites have similar fundamental minima near 2.76 μm, but have distinct
combination M-OH features between 2.24 and 2.36 μm. We show that with expanded spectral libraries that include intermediate composition smectites and both Fe(III) and Fe(II) oxidation states, more
refined characterization of smectites from MIR data is now possible, as the position of the 450 cm–1
absorption shifts systematically with octahedral Fe content, although detailed analysis is best accomplished in concert with other characterization methods. Our data also provide the first Raman spectral
libraries of smectite clays as a function of chemistry, and we demonstrate that Raman spectroscopy
at multiple excitation wavelengths can qualitatively distinguish smectite clays of different structures
and can enhance interpretation by other types of analyses. Our sample set demonstrates how X-ray
diffraction can distinguish between dioctahedral and trioctahedral smectites using either the (02,11) or
(06,33) peaks, but auxiliary information about chemistry and oxidation state aids in specific identifications. Finally, the temperature-dependent isomer shift and quadrupole splitting in Mössbauer data are
insensitive to changes in Fe content but reliability differentiates Fe within the smectite mineral structure.

^1,2Zhang A.-C.,^1,3Jiang Q.-T.,⁴Tomioka N.,⁵Guo Y.-J.,¹Chen J.-N.,^2,6Li Y.,⁷Sakamoto N.,^7,8Yurimoto H.
Geophysical Research Letters 48, e2020GL091554 Link to Article [DOI 10.1029/2020GL091554]
¹State Key Laboratory for Mineral Deposits Research, School of Earth Science and Engineering, Nanjing University, Nanjing, China
²CAS Center for Excellence in Comparative Planetology, Hefei, China
³Now at Department of Geology & Geophysics, Yale University, New Haven, United States
⁴Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Nankoku, Japan
⁵CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, China
⁶Center for Lunar and Planetary Sciences, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
⁷Isotope Imaging Laboratory, Creative Research Institution, Hokkaido University, Sapporo, Japan
⁸Department of Natural History Sciences, Hokkaido University, Sapporo, Japan

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¹Hao B.,¹Ye Z.,¹Xu J.,¹Li L.,¹Huang J.,¹Peng X.,¹Li D.,²Jin Z.,³Ma G.
Chemical Engineering Journal 410, 128340 Link to Article [DOI 10.1016/j.cej.2020.128340]
¹School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang, 330063, China
²Key Laboratory of Mesoscopic Chemistry of MOE, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China
³Global Energy Interconnection Research Institute Co., Ltd, Beijing, 102209, China

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^1,2Maksimiva, A.A. et al. (>10)
Spectrochimica Acta – Part A: Molecular and Biomolecular SpectroscopyVolume 2485, 119196 Link to Article [DOI
10.1016/j.saa.2020.119196]
¹Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002, Russian Federation
²The Zavaritsky Institute of Geology and Geochemistry of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg, 620016, Russian Federation

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^1,2Zaytsev D.,³Borodin E.N.,⁴Dudorov A.E.,¹Panfilov P.
Earth, Moon and Planets 125, 2 Link to Article [DOI 10.1007/s11038-021-09539-x]
¹Institute of Natural Sciences and Mathematics, Ural Federal University, 620002 Mira str., 19, Ekaterinburg, Russian Federation
²The Institute of High Temperature Electrochemistry of the Ural Branch of the Russian Academy of Sciences, st. Akademicheskaya, 20, Yekaterinburg, 620137, Russian Federation
³Mechanics and Physics of Solids Research Group, Department of MACE, The University of Manchester, Manchester, M13 9PL, United Kingdom
⁴Department of Physics, Chelyabinsk State University, 454001 Br. Kashirinykh str., 129, Chelyabinsk, Russian Federation

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^1,2Chaitanya Giri,²Andrew Steele,³Marc Fries
Planetary and Space Sciences (in Press) Link to Article [https://doi.org/10.1016/j.pss.2021.105267]
¹Earth-Life Science Institute, Tokyo Institute of Technology, 2-12-1-IE-1 Ookayama, Meguro-ku, Tokyo, 152-8550, Japan
²Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road NW, Washington, DC, 20015, USA
³Astromaterials Research and Exploration Science Division, NASA Johnson Space Center, Houston, TX, 77058, USA

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^1,2K. K. Brugman,^1,3M. G. Phillips,¹C. B. Till
Journal of Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2020JE006731]
¹School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
²Earth & Planets Laboratory, Carnegie Institution for Science, Washington, D.C. USA
³United States Geological Survey, Moffett Field, CA USA
Published by arrangement with John Wiley & Sons

For rocky exoplanets, knowledge of their geologic characteristics such as composition and mineralogy, surface recycling mechanisms, and volcanic behavior are key to determining their suitability to host life. Thus, determining exoplanet habitability requires an understanding of surface chemistry, and understanding the composition of exoplanet surfaces necessitates applying methods from the field of igneous petrology.

Piston-cylinder partial melting experiments were conducted on two hypothetical rocky exoplanet bulk silicate compositions. HEX1, a composition with molar Mg/Si = 1.42 (higher than bulk silicate Earth’s Mg/Si = 1.23) yields a solidus similar to that of Earth’s undepleted mantle. However, HEX2, a composition with molar Ca/Al = 1.07 (higher than Earth Ca/Al = 0.72) has a solidus with a slope of ∼10°C/kbar (versus ∼15°C/kbar for Earth) and as result, has much lower melting temperatures than Earth. The majority of predicted adiabats point toward the likely formation of a silicate magma ocean for exoplanets with a mantle composition similar to HEX2. For adiabats that do intersect HEX2’s solidus, decompression melting initiates at pressures more than 4x greater than in the modern Earth’s undepleted mantle. The experimental partial melt compositions for these exoplanet mantle analogs are broadly similar to primitive terrestrial magmas but with higher CaO, and for the HEX2 composition, higher SiO2 for a given degree of melting.

This first of its kind exoplanetary experimental data can be used to calibrate future exoplanet petrologic models and predict volatile solubilities, volcanic degassing, and crust compositions for exoplanets with bulk compositions and ƒO2 similar to those explored herein.

^1,2Amanda A.Tosi,²Maria Elizabeth Zucolotto,³Wania Wolff,¹Julio C.Mendes,⁴Sergio Suárez,^5,6Pablo Daniel Pérez,⁷Diana P.P.Andrade
Planetary and Space Science (in Press) Link to Article [https://doi.org/10.1016/j.pss.2021.105250]
¹LABSONDA/IGEO/UFRJ, Instituto de Geociências, Universidade Federal do Rio de Janeiro, Av. Athos da Silveira Ramos, 274, Cidade Universitária, 21941-972, Rio de Janeiro, RJ, Brazil
²LABET/MN/UFRJ, Laboratório Extraterrestre, Departamento de Geologia e Paleontologia, Museu Nacional, Universidade Federal do Rio de Janeiro, Quinta da Boa Vista, São Cristóvão, 20940-040 Rio de Janeiro, RJ, Brazil
³Instituto de Física, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
⁴Divisiones Atômicas, Centro Atomico Bariloche (CONICET), Av. Bustillo 10000, San Carlos de Bariloche, Argentina
⁵Departamento de Ciencias Físicas, Universidad de La Frontera (UFRO), Temuco, Chile
⁶Centro de Física e Ingeniería en Medicina (CFIM), Universidad La Frontera (UFRO), Temuco, Chile
⁷Observatório do Valongo, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil

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^1,2E.J.Allender,¹C.R.Cousins,²M.D.Gunn,¹E.R.Mare
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2021.114541]
¹University of St Andrews, School of Earth and Environmental Sciences, Irvine Building, St Andrews KY16 9AL, UK
²Aberystwyth University, Department of Physics, Penglais Campus, Aberystwyth SY23 3BZ, UK
Copyright Elsevier

A key goal of the ExoMars rover Rosalind Franklin is to analyze accessible hydrated mineral deposits using panoramic multiscale and multispectral imagery. We conducted a multiscale spectroscopic study on hydrothermally-altered basalt-hosted soils in the geothermal area of Námafjall in northern Iceland. Basaltic lavas here that have experienced first-order geochemical alteration produce a variety of cm-to-meter scale poorly-crystalline alteration patterns. The resulting unconsolidated sediments provide a natural analogue material to investigate intimately mixed soils comprising multiple poorly-crystalline hydrated phases. We use emulator instruments which replicate the capabilities of the ExoMars 2022 Panoramic Camera (PanCam), the Infrared Spectrometer for ExoMars (ISEM), and the CLose-UP Imager (CLUPI), alongside Raman, aerial, and X-Ray Fluorescence spectroscopic data to investigate how the detection of these mixed basalt-derived alteration phases varies as a function of spatial and spectral scale. We find soils at our study site to be comprised of unconsolidated sediments including Al-OH minerals, hydrated silica, and a variety of ferric oxides, all of which Rosalind Franklin will likely encounter along its traverse at Oxia Planum. We report on (i) the synergy and limitations between Mars rover instrument emulators as an integral part of mission preparation, (ii) how the mixed nature of these hydrothermally-altered soils affects resulting mineralogical interpretations at multiple scales, and (iii) geochemical inferences that can be made using ExoMars 2022 imaging emulators.