^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.

¹Marco Veneranda et al. (>10)
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2021.114542]
¹University of Valladolid, Ave. Francisco Vallés, 8, 47151 Valladolid, Spain
Copyright Elsevier

This work presents the latest chemometric tools developed by the RLS science team to optimize the scientific outcome of the Raman system onboard the ExoMars 2022 rover. Feldspar, pyroxene and olivine samples were first analyzed through the RLS ExoMars Simulator to determine the spectroscopic indicators to be used for a proper discrimination of mineral phases on Mars. Being the main components of Martian basaltic rocks, lepidocrocite, augite and forsterite were then used as mineral proxies to prepare binary mixtures. By emulating the operational constraints of the RLS, Raman datasets gathered from laboratory mixtures were used to build external calibration curves. Providing excellent coefficients of determination (R2 0.9942÷0.9997), binary curves were finally used to semi-quantify ternary mixtures of feldspar, pyroxene and olivine minerals. As Raman results are in good agreement with real concentration values, this work suggests the RLS could be effectively used to perform semi-quantitative mineralogical studies of the basaltic geological units found at Oxia Planum. As such, crucial information about the geological evolution of Martian Crust could be extrapolated. In light of the outstanding scientific impact this analytical method could have for the ExoMars mission, further methodological improvements to be discussed in a dedicated work are finally proposed.

^1,2K.L.Villalon,³K.K.Ohtaki,³J.P.Bradley,³H.A.Ishii,^1,2,4A.M.Davis,^1,2T.Stephan
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2021.05.041]
¹Department of the Geophysical Sciences, The University of Chicago, Chicago, IL, USA
²Chicago Center for Cosmochemistry, University of Hawai‘i at Mānoa, Honolulu, HI, USA
³Hawai‘i Institute of Geophysics & Planetology, University of Hawai‘i at Mānoa, Honolulu, HI, USA
⁴Enrico Fermi Institute, The University of Chicago, Chicago, IL, USA
Copyright Elsevier

Amorphous silicates containing abundant nano-inclusions have been reported in the Paris CM chondrite (Leroux et al., 2015). They have chemical and morphological similarities to glass with embedded metal and sulfides (GEMS) found in interplanetary dust particles (IDPs) and micrometeorites believed to originate from comets. We used scanning transmission electron microscopy (STEM) with energy-dispersive X-ray spectroscopy (EDS) and nanodiffraction to study the chemistry and mineralogy of these inclusions in order to understand the origin of the GEMS-like material in Paris and its possible relationships to other materials found in primitive chondritic materials including IDP GEMS. EDS and diffraction analyses indicate compositional and mineralogical differences between the nanophase inclusions in cometary GEMS and Paris GEMS-like material. Metal inclusions are notably absent within Paris amorphous silicate. Ni-rich sulfides, including pentlandite, are common in even the least altered matrix material of Paris, while they are absent in GEMS-bearing IDPs and Ultracarbonaceous Antarctic Micrometeorites (UCAMMs). From examination of the inclusions, we cannot yet confirm or refute the possibility that GEMS-like material in Paris is related to cometary GEMS. The distinct compositions and mineralogy of the Paris material may be due to aqueous alteration of cometary GEMS precursors, but they may also denote an independent origin for meteoritic GEMS-like assemblages.

^1,2Gavin G.Kenny,²Claire O.Harrigan,²Mark D.Schmitz,²James L.Crowley,²Corey J.Wall,³Marco A.G.Andreoli,³Roger L.Gibson,⁴Wolfgang D.Maier
Earth and Planetary Science Letters 567, 117013 Link to Article [https://doi.org/10.1016/j.epsl.2021.117013]
¹Department of Geosciences, Swedish Museum of Natural History, SE-104 05 Stockholm, Sweden
²Isotope Geology Laboratory, Department of Geosciences, Boise State University, 1910 University Drive, Boise, ID 83725, USA
³School of Geosciences, University of the Witwatersrand (WITS), Johannesburg, South Africa
⁴School of Earth and Ocean Sciences, Cardiff University, Park Place, Cardiff CF10 3AT, UK
Copyright Elsevier

Impact cratering was a fundamental geological process in the early Solar System and, thus, constraining the timescales over which large impact structures cool is critical to understanding the thermal evolution and habitability of early planetary crusts. Additionally, impacts can induce mass extinctions and establishing the precise timing of the largest impacts on Earth can shed light on their role in such events. Here we report a high-precision zircon U–Pb geochronology study of the Morokweng impact structure, South Africa, which appears to have a maximum present-day diameter of ∼80 km. Our work provides (i) constraints on the cooling of large impact melt sheets, and (ii) a high-precision age for one of Earth’s largest impact events, previously proposed to have overlapped the ca. 145 Ma Jurassic–Cretaceous (J–K) boundary. High-precision U–Pb geochronology was performed on unshocked, melt-grown zircon from five samples from a borehole through approximately 800 m of preserved impact melt rock. Weighted mean 206Pb/238U dates for the upper four samples are indistinguishable, with relative uncertainties (internal errors) of better than 20 ka, whereas the lowermost sample is distinguishably younger than the others. Thermal modeling suggests that the four indistinguishable dates are consistent with in situ conductive cooling of melt at this location within 30 kyr of the impact. The younger date from the lowest sample cannot be explained by in situ conductive cooling in line with the overlying samples, but the date is within the ∼65 kyr timeframe for melt-present conditions in footwall rocks below the impact melt sheet that is indicated by our thermal model. The Morokweng impact event is here constrained to 146.06 ± 0.16 Ma (2σ; full external uncertainty), which precedes current estimates of the age of the J–K boundary by several million years.

¹Laurette Piani,¹Yves Marrocchi,²Lionel G.Vacher,³Hisayoshi Yurimoto,⁴Martin Bizzarro
Earth and Planetary Science Letters 567, 117008 Link to Article [https://doi.org/10.1016/j.epsl.2021.117008]
¹Université de Lorraine, CNRS, CRPG, UMR 7358, Vandoeuvre les Nancy, France
²Laboratory for Space Sciences and the Department of Physics, Washington University in St. Louis, St. Louis, MO 63130, USA
³Department of Natural History Sciences, Faculty of Science, Hokkaido University, Sapporo, Japan
⁴StarPlan – Centre for Star and Planet Formation, GLOBE Institute, University of Copenhagen, Øster Voldgade 5-7, Copenhagen, DK-1350, Denmark
Copyright Elsevier

Chondrites are rocky fragments of asteroids that formed at different times and heliocentric distances in the early solar system. Most chondrite groups contain water-bearing minerals, attesting that both water-ice and dust were accreted on their parent asteroids. Nonetheless, the hydrogen isotopic composition (D/H) of water in the different chondrite groups remains poorly constrained, due to the intimate mixture of hydrated minerals and organic compounds, the other main H-bearing phase in chondrites. Building on our recent works using in situ secondary ion mass spectrometry analyses, we determined the H isotopic composition of water in a large set of chondritic samples (CI, CM, CO, CR, and C-ungrouped carbonaceous chondrites) and report that water in each group shows a distinct and unique D/H signature. Based on a comparison with literature data on bulk chondrites and their water and organics, our data do not support a preponderant role of parent-body processes in controlling the D/H variations among chondrites. Instead, we propose that the water and organic D/H signatures were mostly shaped by interactions between the protoplanetary disk and the molecular cloud that episodically fed the disk over several million years. Because the preservation of D-rich interstellar water and/or organics in chondritic materials is only possible below their respective sublimation temperatures (160 and 350–450 K), the H isotopic signatures of chondritic materials depend on both the timing and location at which their parent body formed.