Fe-ni-p-s melt pockets in elga iie iron meteorite: Evidence for the origin at high-pressures up to 20 gpa

1,2Litasov, K.D.,3Teplyakova, S.N.,1,2Shatskiy, A.,4Kuper, K.E.
Minerals 9, 616 Link to Article [DOI: 10.3390/min9100616]
1Sobolev Institute of Geology and Mineralogy SB RAS, Novosibirsk, 630090, Russian Federation
2Department of Geology and Geophysics, Novosibirsk State University, Novosibirsk, 630090, Russian Federation
3Vernadsky Institute of Geochemistry and Analytical Chemistry RAS, Moscow, 119334, Russian Federation
4Budker Institute of Nuclear Physics SB RAS, Novosibirsk, 630090, Russian Federation

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Miniaturized, rapid separation of neodymium from ultramafic and chondritic samples prior to high precision measurements of 142,143Nd/144Nd isotope ratios by TIMS

1Pin, C.,2Gannoun, A.
Journal of Analytical Atomic Spectroscopy 34, 2136-2146 Link to Article [DOI: 10.1039/c9ja00272c]
1Géologie, CNRS, Université Clermont-Auvergne, Campus des Cézeaux, 6 avenue Blaise Pascal, Aubière Cedex, 63 178, France
2Laboratoire Magmas et Volcans, Université Clermont Auvergne, CNRS, UMR 6524, OPGC-IRD, Clermont-Ferrand, F-63000, France

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Study of the Pallasite Radiation History by Track Analysis

1Alexeev, V.A.,2Bagulya, A.V.,2,3,4Volkov, A.E.,2Gippius, A.A.,2Goncharova, L.A.,2Gorbunov, S.A.,6Grachev, V.M.,3Dashkina, A.B.,1 Kalinina, G.V.,2,5Konovalova, N.S.,2,5Okateva, N.M.,1Pavlov,1T.A.,2,5,6Polukhina, N.,2,5Starkov, N.I.,2Soe, T.N.,2Chernyvsky, M.M.,2,5Shchedrina, T.V.
Bulletin of the Lebedev Physics Institute 46, 251-255 Link to Article [DOI: 10.3103/S1068335619080037]
1Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, 19 Kosygina St., Moscow, 119991, Russian Federation
2Lebedev Physical Institute, Russian Academy of Sciences, 53 Leninskii Pr., Moscow, 119991, Russian Federation
3Russian Scientific Center “Kurchatov Institute”, 1 Kurchatova Sq., Moscow, 123182, Russian Federation
4Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, 6 Joliot-Curie St., Dubna, Moscow Region, 141980, Russian Federation
5National University of Science and Technology “MISIS”, 4 Leninskii Pr., Moscow, 119049, Russian Federation
6National Research Nuclear University “MEPhI”, 31 Kashirskoe Sh., Moscow, 115409, Russian Federation

Extending the dynamic range of biomedical micro-computed tomography for application to geomaterials

1,2Edey, D.R.,1Pollmann, S.I.,1,3Lorusso, D.,1,4,5Drangova, M.,2Flemming, R.L.,1,4,5Holdsworth, D.W.
Journal of X-ray Sciences and Technology 27, 919-934 Link to Article [DOI: 10.3233/XST-190511]
1Imaging Research Laboratories, Robarts Research Institute, Schulich School of Medicine Dentistry, Western University, London, ON, Canada
2Department of Earth Sciences, Western University, London, ON, Canada
3Department of Physiology and Pharmacology, Schulich School of Medicine Dentistry, Western University, London, ON, Canada
4Department of Surgery, Schulich School of Medicine Dentistry, Western University, London, ON, Canada
5Department of Medical Biophysics, Schulich School of Medicine Dentistry, Western University, London, ON, Canada

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Measured atmospheric 36Ar/38Ar, 20Ne/22Ne, 36Ar/22Ne noble gas isotope and bulk K/U ratios constrain the early evolution of Venus and Earth

1H.Lammer,1,2M.Leitzinger,1M.Scherf,1,2P.Odert,3C.Burger,1D.Kubyshkina,3C.Johnstone,3T.Maindl,4C.M.Schäfer,3M.Güdel,5,6N.Tosi,5,6A.Nikolaou,7E.Marcq,8,9N.V.Erkaevh,10L.Noack,1K.G.Kislyakovac,1L.Fossati,3E.Pilat-Lohinger,3F.Ragossnig,3E.A.Dorfi
Icarus (in Press) Link to Artice [https://doi.org/10.1016/j.icarus.2019.113551]
1Space Research Institute, Austrian Academy of Sciences, Graz, Austria
2Institute of Physics/IGAM, University of Graz, Austria
3Department of Astrophysics, University of Vienna, Austria
4Institute of Astronomy and Astrophysics, University of Tübingen, Germany
5Institute of Planetary Research, Department of Planetary Physics, DLR, Berlin Germany
6Department of Astronomy and Astrophysics, Berlin Institute of Technology, Germany
7LATMOS, Université de Versailles Saint-Quentin-en-Yvelines, Guyancourt, France
8Institute of Computational Modelling SB RAS, Krasnoyarsk, Russian Federation
9Siberian Federal University, Krasnoyarsk, Russian Federation
10Department of Earth Sciences, Freie Universität Berlin, Germany
Copyright Elsevier

The atmospheric noble gas isotope and elemental bulk ratios on Venus and Earth provide important information on their origin and evolution. If the protoplanets grew to a certain mass (i.e. > 0.5 MEarth), they could have captured H2-dominated primordial atmospheres by accreting gas from the circumstellar disk during the formation of the Solar System, which were then quickly lost by hydrodynamic escape after the disk dissipated. In such a case, the EUV-driven hydrodynamic flow of H atoms dragged heavier elements with it at different rates, leading to changes in their initial isotope ratios. For reproducing Earth and Venus present atmospheric 36Ar/38Ar, 20Ne/22Ne, 36Ar/22Ne, isotope and bulk K/U ratios we applied hydrodynamic upper atmosphere escape and Smooth Particle Hydrodynamics (SPH) impact models for the calculation of captured H2-dominated primordial atmospheres for various protoplanetary masses. We investigated a wide range of possible EUV evolution tracks of the young Sun and initial atmospheric compositions based on mixtures of captured nebula gas, outgassed and delivered material from ureilite, enstatite and carbonaceaous chondrites. Depending on the disk lifetime of ≈ 3-5 Myr (Bollard et al., 2017; Wang et al., 2017) and the composition of accreted material after disk dispersal, we find from the reproduction of the present atmospheric Ar, Ne, and bulk K/U ratios, that early Earth’s evolution can be explained if proto-Earth had accreted masses between ≈ 0.53 − 0.58 MEarth by the time the nebula gas dissipated. If proto-Earth would have accreted a higher mass during the disk lifetime the present atmospheric Ar and Ne isotope ratios can not be reproduced with our model approach. For masses > 0.75MEarth, Earth would have had a problem to get get rid of its primordial atmosphere. If proto-Earth accreted ≈ 0.53 − 0.58MEarth of enstatite-dominated material as suggested by Dauphas (2017) during the disk lifetime, it would have captured a tiny primordial atmosphere that was lost ≈3 Myr after the disk dissipated. In such a case we find that the present-day atmospheric Ar and Ne isotope ratios can be best reproduced if the post-nebula impactors contained ≈ 5% weakly depleted carbonaceous chondritic material and ≈ 95% enstatite chondrites that are strongly depleted in Ar, Ne and moderately volatile elements like potassium. If higher amounts of carbonaceous chondrites were involved in early Earth’s accretion as recently suggested by Schiller et al. (2018), then the Earth’s present atmospheric Ar and Ne ratios can only be reproduced if the involved carbonaceous chondritic post-nebula material was also highly depleted in these noble gases and/or had to be partially be delivered as long as the primordial atmosphere was yet escaping. As long as primordial atmospheres surround the growing protoplanets the abundance of their volatile elements is overwritten by their respective captured solar-like atmospheric abundances. Therefore the initial composition of the protoplanets at the disk dispersal time can not be identified by our method. For masses less than 0.5 MEarth atmospheric escape cannot explain the present-day ratios, i.e. if Earth grew slower then these ratios have to be explained differently (Marty, 2012). If proto-Venus captured a primordial atmosphere it should have grown to masses of ≈ 0.8 − 1.0 MVenus during the time until the disk dissipated and if early Venus accreted its main mass during the disk lifetime than the present atmospheric Ar and Ne isotope ratios and the observed K/U ratios on Venus surface can also be reproduced by the escape of a captured primordial atmosphere that is lost within ≤ 100 Myr, if the Sun was born between a weakly and moderately active young G star. New precise re-measurements of atmospheric noble gases are necessary by future Venus missions to better constrain the material that was involved in the planet’s accretion history and possibly also the EUV activity evolution of the young Sun. In addition, measurements of other moderately volatile element and isotope ratios on the surface such as Rb/U, 64Zn/66Zn, and 39K/41K can give an insight on whether Venus accreted slow or fast, i.e. almost to its final mass within the disk lifetime.

Detection of Crystalline and Fine-grained Calcic Plagioclases on Vesta

1E. Palomba,1E. D’Aversa,2,3T. M. Sato,1,4A. Longobardo,1F. Dirri,5,6S. Aoki,7G. Orton,1G. Sindoni,1F. Oliva,1G. Carrozzo,8Y. Kasaba
The Astrophysical Journal, Letters 882, L22 Link to Article [DOI
https://doi.org/10.3847/2041-8213/ab339e]
1INAF-IAPS, via del Fosso del Cavaliere 100, I-00133 Rome, Italy
2ISAS-JAXA, Sagamihara, Kanagawa 252-5210, Japan
3Hokkaido Information University, Ebetsu, Hokkaido 069-8585, Japan
4DIST-Università Parthenope, Centro Direzionale Isola C4, 80143, Naples, Italy
5Planetary Aeronomy, Royal Belgian Institute for Space Aeronomy, 3 av. Circulaire, B-1180 Brussels, Belgium
6Fonds National de la Recherche Scientifique, rue d’Egmont 5, B-1000 Brussels, Belgium
7NASA/Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
8Planetary Plasma and Atmospheric Research Center, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan

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