Reflectance study of ice and Mars soil simulant associations – I. H2O ice

1Zuriñe Yoldi,1Antoine Pommerol,1,2Olivier Poch,1Nicolas Thomas
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2020.114169]
1Physikalisches Institut, Universität Bern and NCCR PlanetS, Sidlerstrasse 5, 3012 Bern, Switzerland
2Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
Copyright Elsevier

The reflectance of water ice and dust mixtures depends, amongst other parameters, on how the components are mixed (e.g. intimate mixture, areal mixture or coating) (Clark, 1999). Therefore, when inverting the reflectance spectra measured from planetary surfaces to derive the amount of water ice present at the surface, it is critical to distinguish between different mixing modes of ice and dust. However, the distinction between mixing modes from reflectance spectra remains ambiguous. Here we show how to identify some water ice/soil mixing modes from the study of defined spectral criteria and colour analysis of laboratory mixtures. We have recreated ice and dust mixtures and found that the appearance of frost on a surface increases its reflectance and flattens its spectral slopes, whereas the increasing presence of water ice in intimate mixtures mainly impacts the absorption bands. In particular, we provide laboratory data and a spectral anal

Irradiation origin of 10Be in the solar nebula: Evidence from Li-Be-B and Al-Mg isotope systematics, and REE abundances of CAIs from Yamato-81020 CO3.05 chondrite

1,2Kohei Fukuda,1Hajime Hiyagon,3Wataru Fujiya,4,7Takanori Kagoshima,1,6Keita Itano,1Tsuyoshi Iizuka,2Noriko T.Kita,4,5Yuji Sano
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2020.10.011]
1Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan
2WiscSIMS, Department of Geoscience, University of Wisconsin-Madison, 1215 W. Dayton St., Madison, WI 53706, USA
3Faculty of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan
4Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan
5Institute of Surface-Earth System Science, Tianjin University, Tianjin, 300072, People’s Republic of China
6Present address: College of Science and Engineering, Kanazawa University, Kanazawa 920-1192, Japan
7Present address: Department of Environmental Biology and Chemistry, School of Science, University of Toyama, Toyama 930-8555, Japan
Copyright Elsevier

We have performed in situ analyses of Li-Be-B and Al-Mg isotope systematics, and abundances of rare earth elements (REEs) in two Ca-Al-rich inclusions (CAIs) from the Ornans-like carbonaceous chondrite Yamato-81020 (CO3.05). The present CO CAIs are depleted in ultra-refractory heavy REEs (group II REE pattern), suggesting condensation of these CAIs or their precursors from the solar nebula. Initial 26Al/27Al ratios, (26Al/27Al)0, of these CO CAIs are found to be (4.8 ± 0.5) × 10–5 and (4.9 ± 0.3) × 10–5 (2σ), indicating their contemporaneous formation with a majority of CAIs from CV chondrites. Melilite grains in the present CO CAIs show clear excesses in 10B, ranging from ∼370 to ∼4300‰ relative to the chondritic B isotopic composition, which are correlated well with 9Be/11B ratios. The correlation indicates in situ decay of 10Be in the present CO CAIs and yields initial 10Be/9Be ratios, (10Be/9Be)0, for the individual CAIs of (2.9 ± 0.6) × 10–3 and (2.2 ± 1.0) × 10–3 (2σ), which are significantly greater than the average (10Be/9Be)0 = ∼0.7 × 10–3 recorded in CAIs from Vigarano-like carbonaceous (CV) chondrites. The apparent variation in (10Be/9Be)0 between the CO and CV CAIs, despite having indistinguishable (26Al/27Al)0 of ∼5 × 10–5, provides evidence for heterogeneous distribution of 10Be in the CAI forming-regions at the very beginning of the Solar System. The elevated (10Be/9Be)0 and group II REE patterns in the CO CAIs may reflect that compared with the CV CAIs having unfractionated REEs the present CO CAIs have formed closer to the Sun where 10Be was produced more efficiently through solar cosmic ray irradiation caused by solar flares. Alternatively, if the present CO CAIs and CV CAIs formed in the same region, and 26Al was distributed homogeneously at the CAI-forming region, our results indicate that solar cosmic ray fluxes at the forming region have fluctuated by a factor of six within a short duration (∼0.2 million years) inferred from the Al-Mg chronology.

The most primitive CM chondrites, Asuka 12085, 12169, and 12236, of subtypes 3.0–2.8: Their characteristic features and classification

1Kimura, M.,1Imae, N.,2Komatsu, M.,3Barrat, J.A.,4Greenwood, R.C.,1Yamaguchi, A.,5Noguchi, T.
Polar Science (in Press)  Link to Article [DOI: 10.1016/j.polar.2020.100565]
1National Institute of Polar Research, Tokyo, 190-8518, Japan
2SOKENDAI, Kanagawa, 240-0193, Japan
3Université de Bretagne Occidentale, Institut Universitaire Europé en de La Mer, CNRS UMR 6538, Place Nicolas Copernic, Plouzané 29280, France
4Planetary and Space Sciences, The Open University, Milton Keynes MK7 6AA, United Kingdom
5Kyushu University, Fukuoka, 819-0395, Japan

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The Deccan Volcanic Province (DVP), India: A Review: Part 2: Geochemistry, petrological evolution, petrogenesis, mantle sources, age and erupted volume relations, Upper Cretaceous-Palaeogene (K-Pg) mass extinctions, economic aspects, summary and future studies in DVP

1Krishnamurthy, P.
Journal of the Geological Society of India 96, 111-147 Link to Article [DOI: 10.1007/s12594-020-1521-1]
1Department of Atomic Energy, Begumpet, Formerly Atomic Minerals Directorate for Exploration and Research (AMD), Hyderabad, 500 016, India

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Nanoscale Imaging of High-Field Magnetic Hysteresis in Meteoritic Metal Using X-Ray Holography

1Blukis, R.,2Pfau, B.,3Günther, C.M.,2Hessing, P.,2,4Eisebitt, S., Einsle,5J.,6Harrison, R.J.
Geochemistry, Geophysics, Geosystems 21, e2020GC009044 Link to Article [DOI: 10.1029/2020GC009044]
1GFZ German Centre for Geosciences, Potsdam, Germany
2Max-Born-Institut, Berlin, Germany
3Center for Electron Microscopy (ZELMI), Technische Universität Berlin, Berlin, Germany
4Institut für Optik und Atomare Physik, Technische Universität Berlin, Berlin, Germany
5School of Geographical and Earth Sciences, University of Glasgow, Glasgow, United Kingdom
6Department of Earth Sciences, University of Cambridge, Cambridge, United Kingdom

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Temperature-dependent, VIS-NIR reflectance spectroscopy of sodium sulfates

1S.DeAngelis,2F.Tosi,1C.Carli,2S.Potin,2P.Beck,2O.Brissaud,2B.Schmitt, 1G.Piccioni,1M.C.De Sanctis,1F.Capaccioni
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2020.114165]
1INAF-IAPS, Institute for Space Astrophysics and Planetology, Via del Fosso del Cavaliere, 100, Rome 00133, Italy
2Université Grenoble Alpes, CNRS, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), Grenoble 38058 Cédex 9, France
Copyright Elsevier

Hydrated sodium sulfates have been suggested to be present in variable amounts in Solar System objects such as Mars and Europa, among the possible others. The presence of these hydrated species is related to current/past aqueous environments, thus has an importance regarding the potential habitability of planetary objects. In this study, we analyzed anhydrous sodium sulfate (thénardite) and the hydrated sodium sulfate (mirabilite) by means of visible-infrared reflectance spectroscopy in the 0.4–5 μm spectral range, at different low temperatures between 80 and 298 K. Each mineral has been analyzed in three different grain sizes, between 36 and 150 μm. The anhydrous compound, thénardite, is characterized by a nearly flat spectrum in the visible and near IR up to 2.6 μm, while in the 3–4 μm region, the spectrum shows a few weak features due to H2O and SO42− overtones/combinations. The first strong SO42− overtone is visible at 4.6 μm. Spectra of mirabilite are substantially characterized by H2O absorption features in the 1–3 μm region, and by sulfate overtone/combination bands occurring at 3.8 and 4.7 μm. A weak feature appearing at 2.18 μm is also putatively attributed to the sulfate ion. The bands show changes as a function of temperature. The hydration absorption features in mirabilite show the strongest dependence with temperature, both in terms of shift in position and change of spectral shape. Bands at 3.1–3.24 μm in thénardite, as well as absorption features located at 1.78 and 2.47 μm in mirabilite, could be used as diagnostic proxies for the detection of these two minerals on planetary bodies.

Dynamic aperture factor analysis/target transformation (DAFA/TT) for serpentine and mg-carbonate mapping on Mars with CRISM near-infrared data

1,2Honglei Lin,3J.D.Tarnas,3J.F.Mustard,1Xia Zhang,2Yong Wei,
2Weixing Wan,4F.Klein,5J.R.Kellner
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2020.114168]
1Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100101, China
2Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing. 100029, China
3Dept. of Earth, Environmental, and Planetary Sciences, Brown University, RI 02912, The United States of America
4Dept. of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, MA 02543, The United States of America
5Institute at Brown for Environment and Society, Brown University, RI 02912, The United States of America
Copyright Elsevier

Serpentine and carbonate are products of serpentinization and carbonation processes on Earth, Mars, and other celestial bodies. Their presence implies that localized habitable environments may have existed on ancient Mars. Factor Analysis and Target Transformation (FATT) techniques have been applied to hyperspectral data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) to identify possible serpentine and Mg-carbonate-bearing outcrops. FATT techniques are capable of suggesting the presence of individual spectral signals in complex spectral mixtures. Applications of FATT techniques to CRISM data thus far only evaluate whether an entire analyzed image (≈3 × 105 pixels) may contain spectral information consistent with a specific mineral of interest. The spatial distribution of spectral signal from the possible mineral is not determined, making it difficult to validate a reported detection and also to understand the geologic context of any purported detections. We developed a method called Dynamic Aperture Factor Analysis/Target Transformation (DAFA/TT) to highlight the locations in a CRISM observation (or any similar laboratory or remotely acquired data set) most likely to contain spectra of specific minerals of interest. DAFA/TT determines the locations of possible target mineral spectral signals within hyperspectral images by performing FATT in small moving windows with different geometries, and only accepting pixels with positive detections in all cluster geometries as possible detections. DAFA/TT was applied to a hyperspectral image of a serpentinite from Oman for validation testing in a simplified laboratory setting. The mineral distribution determined by DAFA/TT application to the laboratory hyperspectral image was consistent with Raman analysis of the serpentinite sample. DAFA/TT also successfully mapped the spatial distribution of serpentine and Mg-carbonate previously detected in CRISM data using band parameter mapping and extraction of ratioed spectra. We applied DAFA/TT to CRISM images in some olivine-rich regions of Mars to characterize the spatial distribution of serpentine and magnesite outcrops.

Organic matter from the Chicxulub crater exacerbated the K–Pg impact winter

1Shelby L. Lyons,1Allison T. Karp,1Timothy J. Bralower,2Kliti Grice,
2Bettina Schaefer,3,4,5Sean P. S. Gulick,6Joanna V. Morgan,6Katherine H. Freeman
Proceedings of the National Academy of Sciences of teh United States of America (in Press) Link to Article [https://doi.org/10.1073/pnas.2004596117]
1Department of Geosciences, The Pennsylvania State University, University Park, PA 16802;
2Western Australia Organic and Isotope Geochemistry Centre, School of Earth and Planetary Sciences, The Institute for Geoscience Research, Curtin University, Perth, WA 6102, Australia;
3Institute for Geophysics, University of Texas at Austin, Austin, TX 78758;
4Department of Geological Sciences, University of Texas at Austin, Austin, TX 78712;
5Center for Planetary Systems Habitability, University of Texas at Austin, Austin, TX 78712;
6Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ, United Kingdom

An asteroid impact in the Yucatán Peninsula set off a sequence of events that led to the Cretaceous–Paleogene (K–Pg) mass extinction of 76% species, including the nonavian dinosaurs. The impact hit a carbonate platform and released sulfate aerosols and dust into Earth’s upper atmosphere, which cooled and darkened the planet—a scenario known as an impact winter. Organic burn markers are observed in K–Pg boundary records globally, but their source is debated. If some were derived from sedimentary carbon, and not solely wildfires, it implies soot from the target rock also contributed to the impact winter. Characteristics of polycyclic aromatic hydrocarbons (PAHs) in the Chicxulub crater sediments and at two deep ocean sites indicate a fossil carbon source that experienced rapid heating, consistent with organic matter ejected during the formation of the crater. Furthermore, PAH size distributions proximal and distal to the crater indicate the ejected carbon was dispersed globally by atmospheric processes. Molecular and charcoal evidence indicates wildfires were also present but more delayed and protracted and likely played a less acute role in biotic extinctions than previously suggested. Based on stratigraphy near the crater, between 7.5 × 1014 and 2.5 × 1015 g of black carbon was released from the target and ejected into the atmosphere, where it circulated the globe within a few hours. This carbon, together with sulfate aerosols and dust, initiated an impact winter and global darkening that curtailed photosynthesis and is widely considered to have caused the K–Pg mass extinction.

Mass-independent and mass-dependent Cr isotopic composition of the Rumuruti (R) chondrites: Implication for their origin and their significance for planet formation

1Ke Zhu,1Frédéric Moynier,2Martin Schiller,3ConelM. O’D. Alexander,4Jean-Alix Barrat,5Addi Bischoff,1,2Martin Bizzarro
Geochimica et Cosmochimcia Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2020.10.007]
1Institut de Physique du Globe de Paris, Université de Paris, CNRS UMR 7154, 1 rue Jussieu, Paris F-75005, France
2Centre for Star and Planet Formation, Globe Institute, University of Copenhagen, Øster Voldgade 5–7, Copenhagen DK-1350, Denmark
3Earth and Planetary Laboratory, Carnegie Institution for Science, 5241 Broad Branch Road, Washington, DC 20015, USA4Univ. Brest, CNRS, UMR 6539 (Laboratoire des Sciences de l’Environnement Marin), LIA BeBEST, Institut Universitaire Européen de la Mer (IUEM), Place Nicolas Copernic, 29280 Plouzané, France
5Institut für Planetologie, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Str. 10, D-48149 Münster, Germany
Copyright Elsevier

Chromium (Cr) isotopes play an important role in cosmochemistry and planetary science, because they are powerful tools for dating (53Mn-53Cr short-lived chronometry), tracing (54Cr nucleosynthetic anomalies) the origins of the materials, and studying the processes involved in volatile element fractionation and planetary differentiation (Cr stable isotopic fractionation). The foundation for using Cr isotopes is to precisely know the compositions of the various chondritic reservoirs. However, the Cr isotope composition of Rumuruti (R) chondrites remains unknown. Here, we report high-precision mass-independent (average 2SE uncertainty of ∼0.02 and ∼0.06 for ε53Cr and ε54Cr, respectively; ε indicates 10,000 deviation) and mass-dependent (uncertainty of average 0.03 ‰ for δ53Cr; δ indicates 1,000 deviation) Cr isotope data for 12 bulk R chondrites of petrologic types 3-6 (included R chondrite breccias), and one R chondrite-like clast (MS-CH) in the Almahata Sitta polymict ureilite. All the R chondrites show homogeneous bulk ε54Cr values, -0.06 ± 0.08 (2SD), similar only to those of the Earth-Moon system and enstatite chondrites. These first ε54Cr data for R chondrites provide significant addition to the ε54Cr-Δ17O diagram, and position them as a potential endmember for planetary precursors. The R chondrites possess a higher 55Mn/52Cr of 0.68 ± 0.04 and higher ε53Cr values 0.23 ± 0.05 (2SD) relative to most of other chondrite groups. This likely results from the lower (e.g. than ordinary and enstatite chondrites) chondrule abundance in R chondrites. The stable Cr isotope composition of R chondrites is homogeneous with a δ53Cr = -0.12 ± 0.03 ‰ (2SD). Combined with previous data of other groups of chondrites, we show that the stable Cr isotopic composition of all the chondrites is homogeneous with δ53Cr of -0.12 ± 0.04 ‰ (2SD, N = 40) and is independent of the petrologic type and redox conditions. The lack of mass-dependent fractionation between all groups of chondrites suggests that the average chondrite δ53Cr value is also representative for the initial composition all differentiated planets in the Solar System. Finally, the MS-CH clast in Almahata Sitta has a Cr isotopic composition (ε53Cr = 0.18 ± 0.04, ε54Cr = -0.16 ± 0.07, and δ53Cr = -0.11 ± 0.05 ‰) that is consistent (within error) with it being an R chondrite-like clast.