^1,2Kereszturi Akos, ²Ormandi Szivia, ²Jozsa Sandor, ³Szabo Mate, ³Toth Maria
¹Research Center for Astronomy and Earth Sciences, Konkoly Astronomical Institute, H-1121 Budapest, Konkoly Thege Miklos 15-17., Hungary
²Eotvos Lorand University, Faculty of Sciences, H-1117 Budapest, Pazmany Peter 1/C, Hungary
³Research Center for Astronomy and Earth Sciences, Institute of Geological and Geochemical Research, H-1112 Budapest, Budaorsi 45., Hungary

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Reference
Akos K, Szivi O, Jozsa Sandor J, Szabo Mate S, Maria T(2014) Analysis of ripple or flow-like features in NWA 3118 CV3 Meteorite. Planetary and Space Science (in Press)
Link to Article [DOI: 10.1016/j.pss.2014.09.011]

¹I. Weber,²U. Böttger,³S.G. Pavlov,¹E.K. Jessberger,^2,3H.-W. Hübers
¹Institut für Planetologie, Wilhelm-Klemm-Str. 10, WWU Münster,48149 Münster Germany
²DLR, Institut für Planetenforschung, Rutherfordstr. 2, 12489 Berlin, Germany
³Institut für Optik und Atomare Physik, Technische Universität, Straße des 17. Juni 135, 10623 Berlin, Germany

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Reference
Weber I, Böttger U, Pavlov SG, Jessberger EK, Hübers H-W (2014) Mineralogical and Raman spectroscopy studies of natural olivines exposed to different planetary Environments. Planetary and Space Sciences (in Press)
Link to Article [DOI: 10.1016/j.pss.2014.08.016]

^1,2Martin Schmieder,²Fred Jourdan,^1,Eric Tohver,³Edward A. Cloutis
¹School of Earth and Environment, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
²Western Australian Argon Isotope Facility, Department of Applied Geology and JdL Centre, Curtin University, GPO Box U1987, Perth, WA 6845, Australia
³Planetary Spectrophotometer Facility, Department of Geography, University of Winnipeg, Canada

New 40Ar/39Ar dating of impact-melted K-feldspars and impact melt rock from the ∼40 km Lake Saint Martin impact structure in Manitoba, Canada, yielded three plateau ages and one mini-plateau age in agreement with inverse isochron ages for the K-feldspar melt aliquots and a minimum age for a whole-rock impact melt sample. A combination of two plateau ages and one isochron age, with a weighted mean of 227.8±0.9 Ma227.8±0.9 Ma [±1.1 Ma; including all sources of uncertainty] (2σ ; MSWD = 0.52; P=0.59P=0.59), is considered to represent the best-estimate age for the impact. The concordant 40Ar/39Ar ages for the melted K-feldspars, derived from impact melt rocks in the eastern crater moat domain and the partially melted Proterozoic central uplift granite, suggest that the new dates accurately reflect the Lake Saint Martin impact event in the Carnian stage of the Late Triassic. With a relative error of ±0.4% on the 40Ar/39Ar age, the Lake Saint Martin impact structure counts among the most precisely dated impact structures on Earth. The new isotopic age for Lake Saint Martin significantly improves upon earlier Rb/Sr and (U–Th)/He results for this impact structure and contradicts the hypothesis that planet Earth experienced the formation of a giant ‘impact crater chain’ during a major Late Triassic multiple impact event.

Reference
Schmieder M, Jourdan F, Tohver E, Cloutis EA (2014) 40Ar/39Ar age of the Lake Saint Martin impact structure (Canada) – Unchaining the Late Triassic terrestrial impact craters. Earth and Planetary Science Letters (in Press)
Link to Article [DOI: 10.1016/j.epsl.2014.08.037]

Copyright Elsevier

^1,3W.M. Farrell,^2,3D.M. Hurley,^2,3M.I. Zimmerman
¹NASA/Goddard Space Flight Center, Greenbelt, MD
²Johns Hopkins University/Applied Physics Laboratory, Laurel, MD
³NASA’s Solar System Exploration Research Virtual Institute, NASA/Ames Research Center, Moffett Field, CA, 08101414

Solar wind protons are implanted directly into the top 100 nanometers of the lunar near-surface region, but can either quickly diffuse out of the surface or be retained, depending upon surface temperature and the activation energy, U, associated with the implantation site. In this work, we explore the distribution of activation energies upon implantation and the associated hydrogen-retention times; this for comparison with recent observation of OH on the lunar surface. We apply a Monte Carlo approach: for simulated solar wind protons at a given local time, we assume a distribution of U values with a central peak, Uc and width, Uw, and derive the fraction retained for long periods in the near-surface. We find that surfaces characterized by a distribution with predominantly large values of U (> 1 eV) like that expected at defect sites will retain implanted Hs (to likely form OH). Surfaces with the distribution predominantly at small values of U (< 0.2 eV) will quickly diffuse away implanted Hs. However, surfaces with a large portion of activation energies between 0.3 eV < U < 0.9 eV will tend to be H-retentive in cool conditions but transform into H-emissive surfaces when warmed (as when the surface rotates into local noon). These mid-range activation energies give rise to a diurnal effect with diffusive loss of H at noontime.

Reference
Farrell WM,Hurley DM, Zimmerman MI (2014) Solar wind implantation into lunar regolith: Hydrogen retention in a surface with defects. Icarus (in Press)
Link to Article [DOI: 10.1016/j.icarus.2014.09.014]

Copyright Elsevier

¹Maud Boyet,²Richard W. Carlson,³Lars E. Borg,²Mary Horan
¹Clermont Université, Université Blaise Pascal, Laboratoire Magmas et Volcans, UMR 6524, 5 rue Kessler 63038 Clermont-Ferrand, France
²Department of Terrestrial Magnetism 5241 Broad Branch Road, NW Washington, DC 20015-1305 USA
³Chemical Sciences Division, Lawrence Livermore National Laboratory, 7000 East Avenue L-231, Livermore CA 94550 USA

We have measured Sm-Nd systematics, including the short-lived 146Sm-142Nd chronometer, in lunar ferroan anorthositic suite (FAS) whole rocks (15415, 62236, 62255, 65315, 60025). At least some members of the suite are thought to be primary crystallization products formed by plagioclase flotation during crystallization of the lunar magma ocean (LMO). Most of these samples, except 62236, have not been exposed to galactic cosmic rays for a long period and thus require minimal correction to their 142Nd isotope composition. These samples all have measured deficits in 142Nd relative to the JNdi-1 terrestrial standard in the range -45 to -21 ppm. The range is -45 to -15 ppm once the 62236 142Nd/144Nd ratio is corrected from neutron-capture effects. Analyzed FAS samples do not define a single isochron in either 146Sm-142Nd or 147Sm-143Nd systematics, suggesting that they either do not have the same crystallization age, come from different sources, or have suffered isotopic disturbance. Because the age is not known for some samples, we explore the implications of their initial isotopic compositions for crystallization ages in the range of 50-300 Ma after the beginning of accretion, a timing interval that covers all the ages determined for the ferroan anorthositic suite whole rocks as well as different estimates for the crystallization of the LMO. 62255 has the largest deficit in initial 142Nd and does not appear to have followed the same differentiation path as the other FAS samples. The large deficit in 142Nd of FAN 62255 may suggest a crystallization age around 60-125 Ma after the beginning of solar system accretion. This result provides essential information about the age of the giant impact forming the Moon. The initial Nd isotopic compositions of FAS samples can be matched either with a bulk-Moon with chondritic Sm/Nd ratio but enstatite-chondrite-like initial 142Nd/144Nd (e.g. 10 ppm below modern terrestrial), or a bulk-Moon with superchondritic Sm/Nd ratio and initial 142Nd/144Nd similar to ordinary chondrites.

Reference
Boyet M, Carlson RW, Borg LE, Horan M (2014) Sm-Nd systematics of lunar ferroan anorthositic suite rocks: Constraints on lunar crust Formation. Geochimica et Cosmochimica Acta (in Press)
Link to Article [DOI: 10.1016/j.gca.2014.09.021]

Copyright Elsevier

These are the five most popular papers based on the interest (clicks) on this blog during September 2014:

1-Ott U (2014) Planetary and pre-solar noble gases in meteorites. Chemie der Erde (in Press)
Link to Articel [DOI: 10.1016/j.chemer.2014.01.003]

2-Kruijer TS, Thorsten Kleine T, Mario Fischer-Gödde M, Christoph Burkhardt C, Wieler R (2014) Nucleosynthetic W isotope anomalies and the Hf–W chronometry of Ca–Al-rich inclusions. Earth and Planetary Science Letters 403,317–327.
Link to Article [DOI: 10.1016/j.epsl.2014.07.003]

3-Anfinogenov J, Budaeva L, Kuznetsov D, Anfinogenova Y (2014) John’s Stone: a possible fragment of the 1908 Tunguska Meteorite. Icarus (in Press)
Link to Article [DOI: 10.1016/j.icarus.2014.09.006]

4-Hansen CJ, Andersen AC, Christlieb N (2014) Stellar abundances and presolar grains trace the nucleosynthetic origin of molybdenum and Ruthenium. Astronomy & Astrophysics 568, A47
Link to Article [http://dx.doi.org/10.1051/0004-6361/201423535]

5-Schwander D, Berg T, Schönhense G, Ott U (2014) Condensation of Refractory Metals in Asymptotic Giant Branch and Other Stellar Environments. The Astrophysical Journal 793 (in Press)
Link to Article [doi:10.1088/0004-637X/793/1/20]

^1,2,3Jonathan Fraine,^1,4Drake Deming,³Bjorn Benneke,³Heather Knutson,²Andrés Jordán,²Néstor Espinoza,⁵Nikku Madhusudhan,¹Ashlee Wilkins⁶Kamen Todorov

¹Department of Astronomy, University of Maryland, College Park, Maryland 20742-2421, USA
²Instituto de Astrofísica, Pontificia Universidad Católica de Chile, 7820436 Macul, Santiago, Chile
³Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA
⁴NASA Astrobiology Institute’s Virtual Planetary Laboratory, Seattle, Washington 98195, USA
⁵Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
⁶Department of Physics, ETH Zürich, 8049 Zürich, Switzerland

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Reference
Fraine J, Deming D, Benneke B, Knutson H, Jordán A, Espinoza N, Madhusudhan N, Wilkins A, Todorov K (2014) Water vapour absorption in the clear atmosphere of a Neptune-sized exoplanet. Nature 513, 526–529
Link to Article [doi:10.1038/nature13785 ]

¹L. Ilsedore Cleeves, ¹ Edwin A. Bergin, ² Conel M. O’D. Alexander,¹Fujun Du, ³Dawn Graninger, ³Karin I. Öberg, ⁴Tim J. Harries
¹Department of Astronomy, University of Michigan, 311 West Hall, 1085 South University Avenue, Ann Arbor, MI 48109, USA.
²Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA.
³Harvard-Smithsonian Center for Astrophysics, Harvard University, Cambridge, MA 02138, USA.
⁴Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, UK

Identifying the source of Earth’s water is central to understanding the origins of life-fostering environments and to assessing the prevalence of such environments in space. Water throughout the solar system exhibits deuterium-to-hydrogen enrichments, a fossil relic of low-temperature, ion-derived chemistry within either (i) the parent molecular cloud or (ii) the solar nebula protoplanetary disk. Using a comprehensive treatment of disk ionization, we find that ion-driven deuterium pathways are inefficient, which curtails the disk’s deuterated water formation and its viability as the sole source for the solar system’s water. This finding implies that, if the solar system’s formation was typical, abundant interstellar ices are available to all nascent planetary systems.

Reference
Cleeves LI, Bergin EA, Alexander CMOD, Du F, Graninger D, Öberg KI, Harries TJ (2014) The ancient heritage of water ice in the solar System. Science 345, 1590-1593
Link to Article [DOI: 10.1126/science.1258055]

Published with permission from AAAS

¹Yi Feng, ¹Mark R. Krumholz
¹Department of Astronomy and Astrophysics, University of California, Santa Cruz, California 95064, USA

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Reference
Feng Y, Krumholz MR (2014) Early turbulent mixing as the origin of chemical homogeneity in open star Clusters. Nature 513, 523–525
Link to Article [doi:10.1038/nature13662 ]

^1,2André Izidoro, ¹Alessandro Morbidelli, ³Sean. N. Raymond
¹University of Nice-Sophia Antipolis, CNRS, Observatoire de la Côte d’Azur, Laboratoire Lagrange, BP 4229, F-06304 Nice Cedex 4, France
²Capes Foundation, Ministry of Education of Brazil, Brasília/DF 70040-020, Brazil
³CNRS and Université de Bordeaux, Laboratoire d’Astrophysique de Bordeaux, UMR 5804, F-33270 Floirac, France

Super-Earths with orbital periods less than 100 days are extremely abundant around Sun-like stars. It is unlikely that these planets formed at their current locations. Rather, they likely formed at large distances from the star and subsequently migrated inward. Here we use N-body simulations to study the effect of super-Earths on the accretion of rocky planets. In our simulations, one or more super-Earths migrate inward through a disk of planetary embryos and planetesimals embedded in a gaseous disk. We tested a wide range of migration speeds and configurations. Fast-migrating super-Earths (τmig ~ 0.01-0.1 Myr) only have a modest effect on the protoplanetary embryos and planetesimals. Sufficient material survives to form rocky, Earth-like planets on orbits exterior to the super-Earths’. In contrast, slowly migrating super-Earths shepherd rocky material interior to their orbits and strongly deplete the terrestrial planet-forming zone. In this situation any Earth-sized planets in the habitable zone are extremely volatile-rich and are therefore probably not Earth-like.

Reference
Izidoro A, Morbidelli A, Raymond SN (2014) Terrestrial Planet Formation in the Presence of Migrating Super-Earths. The Astrophysical Journal 794/1
Link to Article [doi:10.1088/0004-637X/794/1/11]