¹Michael W.Broadley,¹David V.Bekaert,¹ Bernard Marty,²Akira Yamaguchi,³Jean-Alix Barrat
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2019.11.032]
¹Centre de Recherches Pétrographiques et Géochimiques, UMR 7358 CNRS—Université de Lorraine, 15 rue Notre Dame des Pauvres, BP 20, F-54501 Vandoeuvre-lès-Nancy, France
²National Institute of Polar Research, Tachikawa, Tokyo 190-8518, Japan
³Laboratoire Geoscience Océan, UMR 6538 CNRS—Université de Bretagne Occidentale et Institut Universitaire Européen de la Mer, Place Nicolas Copernic, 29280 Plouzané, France
Copyright Elsevier

Ureilites are equilibrated carbon-rich olivine-pyroxene rocks from the partially melted mantle of a large (>500 km diameter) heterogeneous parent body. Recently the ureilite parent body was interpreted as an incomplete mixture of material from two carbon-rich chondritic reservoirs, one (Mg-rich) with reduced iron, low Δ¹⁷O and low δ¹³C, and the other with oxidised iron, high Δ¹⁷O and high δ¹³C. Here we analyse noble gases (Ar, Kr and Xe) in six equilibrated (unbrecciated) ureilites from Northwest Africa (NWA 2236, NWA 7686, NWA 8049, NWA 8172, NWA 11032 and NWA 11368). We observe weak positive and negative correlations of Δ¹⁷O and Mg# with the elemental ratios of Ar/Xe and Kr/Xe, respectively, as well as a weak positive correlation of Mg# with the heavy isotopes of Xe. These correlations broadly support the idea of the two-component mixing hypothesis. Our analyses further suggest that the Mg-rich endmember was rich in Xe from presolar grains (HL-Xe) while the Mg-poorer component may have contained solar-derived noble gases. The observed correlations are less straightforward to reconcile with a recent model for the origin of the ureilite parent body, involving oxidation of metal by H₂O from accreted ice with ‘heavy’ oxygen isotopes.

¹Ryan C.Ogliore,²Russell L.Palma,³ Julien Stodolna,⁴Kazuhide Nagashima,⁵Robert O.Pepin,⁵ D.J.Schlutter,⁶Zack Gainsforth,⁶Andrew J.Westphal,⁴Gary R.Huss
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2019.11.033]
¹Department of Physics, Washington University in St. Louis, St. Louis, MO 63130
²Minnesota State University – Mankato
³EDF Lab les Renardiéres 77818 Moret Sur Loing France
⁴Hawai‘i Institute of Geophysics and Planetology, University of Hawai‘i at Mānoa, Honolulu, HI 96822
⁵University of Minnesota – Twin Cities
⁶Space Sciences Laboratory, University of California at Berkeley
Copyright Elsevier

We report the structure, chemical composition, O, Al-Mg, He, and Ne isotope systematics of an interplanetary dust particle, “Manchanito”. These analyses indicate that Manchanito solidified as refractory glass (with oxidized Fe but reduced Ti) in a chondrule-like formation environment more than 3.2 Myr after CAIs, after which it was exposed to Q-like noble gases in the dissipating solar nebula. Manchanito’s He and Ne isotopic composition and concentrations are similar to those measured in samples of comet Wild 2, from which we infer that Manchanito’s parent body was a comet. We propose that after formation and exposure to Q-like gases, Manchanito was transported to the outer Solar System where it came into contact with organics and volatile ices on its cometary parent body. Manchanito provides additional evidence that cometary solids have been subjected to energetic processing and large-scale transport in a wide range of environments in the Solar System.

¹A. P. Jones,¹N. Ysard
Astronomy & Astrophysics 627, A38 Link to Article [https://doi.org/10.1051/0004-6361/201935532]
¹Astrophysique Spatiale, CNRS/Université Paris-Sud, Université Paris-Saclay, Bâtiment 121, Université Paris-Sud, 91405 Orsay Cedex, France

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^1,2,6S. T. Zeegers,^1,4 E. Costantini, ¹D. Rogantini,¹C. P. de Vries,³H. Mutschke,³P. Mohr,⁵F. de Groot,²A. G. G. M. Tielens
Astronomy & Astrophysics 627, A16 Link to Article [DOI ttps://doi.org/10.1051/0004-6361/201935050]
¹SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
²Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
³Astrophysikalisches Institut und Universitäts-Sternwarte (AIU), Schillergäßchen 2-3, 07745 Jena, Germany
⁴Anton Pannekoek Astronomical Institute, University of Amsterdam, PO Box 94249, 1090 GE Amsterdam, The Netherlands
⁵Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
⁶Academia Sinica, Institute of Astronomy and Astrophysics, 11F Astronomy-Mathematics Building, NTU/AS campus, No. 1, Section 4, Roosevelt Rd., Taipei 10617, Taiwan

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¹P. Thebault,¹Q. Kral
Astronomy & Astrophysics 626, A24 Link to Article [DOI https://doi.org/10.1051/0004-6361/201935341 ]
¹LESIA – Observatoire de Paris, UPMC Université Paris 06, Université Paris-Diderot, Paris, France

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¹Baohua Zhang,^1,2Jianhua Ge,^1,2Zili Xiong,¹Shuangmeng Zhai
Journal of Geophysical Research, Planets (in Press) Link to Article [https://doi.org/10.1029/2019JE006194]
¹Key Laboratory for High‐Temperature and High‐Pressure Study of the Earth’s Interior, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, Guizhou, China
²University of Chinese Academy of Sciences, Beijing, China
Published by arrangement with John Wiley & Sons

How water could affect thermal transport properties is a key question which needs to be quantified experimentally when it is incorporated as structurally bound hydroxyl groups in the lattice of mantle minerals. In this study, thermal diffusivity (D) and thermal conductivity (κ) of San Carlos olivine aggregates with various water contents (up to 0.2 wt.% H₂O) were measured simultaneously using transient plane‐source method up to 873 K and 3 GPa. Experimental results demonstrate water content can significantly reduce the thermal diffusivity (D) and thermal conductivity (κ) of olivine aggregate. With the increase of H₂O content from 0.08 wt.% to 0.2 wt.%, the absolute values of D and κ for olivine samples decrease by 5–13% and 17–33% and by 3–8% and 14–21%, respectively. D and κ of olivine aggregate decrease with temperature but increase with pressure. Heat capacity is influenced by pressure negatively. Combining the present data with surface heat flow of the Moon as well as heat production, the calculated temperature profiles provide new constraints on the lunar geotherm and possible H₂O content in the lunar interior.

^1,2,3N.R. Alsaeed,^4,5B.M. Jakosky
Journal of Geophysical Research, Planets (in Press) Link to Article [https://doi.org/10.1029/2019JE006066]
¹Department of Astrophysical and Planetary Sciences, University of Colorado Boulder, Boulder, CO, USA
²Laboratory for Atmospheric and Space Physics, Boulder, CO, USA
³Mohammed Bin Rashid Space Center, Dubai, UAE
⁴Laboratory for Atmospheric and Space Physics, Boulder, CO, USA
⁵Department of Geological Sciences, University of Colorado Boulder, Boulder, CO, USA
Published by arrangement with John Wiley & Sons

The current deuterium to hydrogen ratio (D/H) on Mars is enriched by a factor of 5‐6 relative to terrestrial values, suggesting that large amounts of H from water have been lost to space. Loss of H occurs more efficiently than loss of D because H atoms are lighter than D atoms, so the remaining gas becomes enriched in D. We constrain the history of water on Mars using D/H by tracking the supply and loss of H and D in the atmosphere. We examined the evolution of water and D/H from 3.3 Ga to the present, using the measured D/H in an ~3 billion‐year‐old Gale crater mudstone and in the present atmosphere as constraints. We define the boundary conditions by the amount of water present at the surface early in history and the amount of water present today, and incorporate the supply of water from outgassing and loss of H and D to space. The factor‐of‐two enrichment in D/H in the last 3.3 Ga can be produced if loss to space outstrips outgassing. This corresponds to a present‐day 20‐50 m water global equivalent layer (GEL) that is a residual of an initial inventory at 3.3 Ga of 40‐170 m GEL, combined with 5‐100 m GEL outgassed and 20‐220 m GEL lost to space.

^1,2Sterken, V.J.,³Westphal, A.J.,⁴Altobelli, N.,⁵Malaspina, D.,^6,7Postberg, F.
Space Science Reviews 215, 43 Link to Article [DOI: 10.1007/s11214-019-0607-9]
¹Astronomisches Institut Universität Bern (AIUB), Bern, Switzerland
²Institute of Applied Physics (IAP), University of Bern, Bern, Switzerland
³Space Sciences Laboratory, University of California at Berkeley, Berkeley, United States
⁴European Space Agency, ESAC, Madrid, Spain
⁵LASP, University of Colorado, Boulder, United States
⁶Institute of Earth Sciences, University of Heidelberg, Heidelberg, Germany
⁷Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany

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¹Jianguo Wang,²Lei Zhang,²Li Zhong
IOP Conference Series: Earth and Environmental Science 310, 032004 Link to Article [DOI https://doi.org/10.1088/1755-1315/310/3/032004]
¹Department of Geological Engineering, Qinghai University, Xining 810086, China
²TianShi Culture Development Co., Ltd., Xining 810086, China

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¹Berzin, S.V.,¹Ivanov, K.S.,¹Burlakov, E.V.
Doklady Earth Science 487, 908-910 Link to Article [DOI: 10.1134/S1028334X19080245]
¹Zavaritsky Institute of Geology and Geochemistry, Ural Branch, Russian Academy of Sciences, Yekaterinburg, 620016, Russian Federation

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