1Rachel L. Klima, 2Noah E. Petro
Philosophical Transactions of the Royal Society A 375 Link to Article [https://doi.org/10.1098/rsta.2015.0391]
1Space Exploration Sector, Planetary Exploration Group, Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA
2NASA Goddard Space Flight Center, Greenbelt, MD, USA
We currently do not have a copyright agreement with this publisher and cannot display the abstract here
1L.J.Hallis
Philosophical Transactions of the Royal Society A 375 Link to Article [DOI: 10.1098/rsta.2015.0390]
1School of Geographical and Earth Sciences, Gregory Building, University of Glasgow, Glasgow G12 8QQ, UK
We currently do not have a copyright agreement with this publisher and cannot display the abstract here
1,2S. Sutton, 3C.M.O’D. Alexander, 1A. Bryant, 1A. Lanzirotti, 1M. Newville, 4E.A. Cloutis
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2017.05.021]
1Center for Advanced Radiation Sources, 5640 S. Ellis Avenue, University of Chicago, Chicago, IL 60637, USA
2Department of Geophysical Sciences, 5640 S. Ellis Avenue, University of Chicago, Chicago, IL 60637, USA
3DTM, Carnegie Institution of Washington, 5241 Broad Branch Road, Washington, DC 20015, USA
4Department of Geography, University of Winnipeg, 515 Portage Avenue, Winnipeg, Manitoba, Canada, R3B 2E9.
Copyright Elsevier
There is abundant petrologic evidence for the oxidation of Fe during the aqueous alteration of chondrites, and water must have been the oxidant for this process. The H2 lost from the chondrite parent bodies as a result of Fe oxidation would have been isotopically very light, enriching any residual water in D. The extents of the D enrichments will have depended on the fractions of water consumed and the temperatures during Fe oxidation. Here we have estimated the likely ranges of water consumed by Fe oxidation in the CI, CM, CR and LL parent bodies, as well as the likely range of changes in water H isotopic compositions this would have produced. We first used Fe XANES to determine the Fe valences of bulk meteorite powders in Orgueil (CI1), a number of CMs and CRs that experienced varying degrees of alteration, and Semarkona (LL3.00). The total ranges of bulk Fe valences we obtained were: Orgueil 2.77, CMs 2.40-2.63, CRs 1.46-2.54, and Semarkona 2.10. Combining previous estimates of the present water/OH contents of our samples with the present bulk Fe valences and an estimated range of initial bulk Fe valences, we estimate the likely ranges of fractional water losses to have been: Orgueil 15-26%, Semarkona 73-83%, CMs 23-48%, and CRs 39-62%. The associated maximum and minimum changes in the H isotopic compositions of the remaining water were estimated assuming the equilibrium H2-H2O isotopic fractionation factor, Rayleigh fractionation of the H2, and oxidation temperatures of 0-200°C. Using previous estimates of the water H isotopic compositions in the chondrites, the ranges of estimated δD values for the initial chondritic waters are: Orgueil -672 ‰ to -422 ‰, CMs -676 ‰ to -493 ‰, CRs -527 ‰ to -56 ‰, and Semarkona -527 ‰ to 154 ‰. The CI, CM, CR and ordinary chondrites all accreted water with similar H isotopic compositions that were distinct from the compositions of comets or Saturn’s moon Enceladus. Thus, the carbonaceous chondrites are unlikely to have come from comets or from bodies that were scattered into the Asteroid Belt from comet forming regions by orbital migration of the giant planets. If the carbonaceous chondrites did form in the outer Solar System, as some models predict, it was probably not beyond 7 AU. However, based on water isotopic compositions at present it is equally plausible that the carbonaceous chondrites formed in the inner Solar System.
1Maksimova, A.A., 1Oshtrakh, M.I., 2Felner, I., 1Chukin, A.V., 3Karabanalov, M.S., 1Semionkin, V.A.
Journal of Molecular Structure 1140, 122-126 Link to Article [DOI: 10.1016/j.molstruc.2016.11.042]
1Institute of Physics and Technology, Ural Federal University, Ekaterinburg, Russian Federation
2Racah Institute of Physics, The Hebrew University, Jerusalem, Israel
3Institute of Material Science and Metallurgy, Ural Federal University, Ekaterinburg, Russian Federation
We currently do not have a copyright agreement with this publisher and cannot display the abstract here
1Bossin, L., 2,3Kazakis, N.A., 3Kitis, G., 2Tsirliganis, N.C.
Applied Radiation and Isotopes 127, 26-34 Link to Article [DOI: 10.1016/j.apradiso.2017.05.002]
1Department of Archaeology, Durham University, United Kingdom
2Laboratory of Archaeometry and Physicochemical Measurements, R.C. ‘Athena’, Kimmeria University Campus, P.O. Box 159, Xanthi, Greece
3Nuclear Physics Laboratory, Physics Department, Aristotle University of Thessaloniki, Thessaloniki, Greece
We currently do not have a copyright agreement with this publisher and cannot display the abstract here
1Elewa, N.N., 1Cadogan, J.M.
Hyperfine Interactions 238, 4 Link to Article [DOI: 10.1007/s10751-016-1350-1]
1School of Physical, Environmental and Mathematical Sciences, The University of New South Wales at the Australian Defence Force Academy, Canberra, ACT, Australia
We currently do not have a copyright agreement with this publisher and cannot display the abstract here
1Koga, T., 1,2Naraoka, H.
Scientific Reports 7, 636 Link to Article [DOI: 10.1038/s41598-017-00693-9]
1Department of Earth and Planetray Sciences, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, Japan
2Research Center for Planetary Trace Organic Compounds, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, Japan
We currently do not have a copyright agreement with this publisher and cannot display the abstract here
1G.G. Managadze, 1A.A. Safronova, 1K.A. Luchnikov, 1,2E.A. Vorobyova, 3,4N.S. Duxbury, 5P. Wurz, 1N.G. Managadze, 1Chumikov, 6R.Kh. Khamizov
Astrobiology 17, 448-458 Link to Article [https://doi.org/10.1089/ast.2016.1511]
1Space Research Institute, Russian Academy of Sciences, Moscow, Russian Federation.
2Soil Science Faculty, Lomonosov Moscow State University, Moscow, Russian Federation.
3Department of Physics, Astronomy and Computational Sciences, George Mason University, Fairfax, Virginia, USA.
4Geology Faculty, Lomonosov Moscow State University, Moscow, Russian Federation.
5Physics Institute, University of Bern, Bern, Switzerland.
6Institute of Geological Chemistry, Russian Academy of Sciences, Moscow, Russian Federation.
We currently do not have a copyright agreement with this publisher and cannot display the abstract here
1Paolo A. Sossi, 2Frédéric Moynier
Earth and Planetary Science Letters (in Press) Link to Article [https://doi.org/10.1016/j.epsl.2017.04.029]
1Institut de Physique du Globe de Paris, Université Paris Diderot, Université Sorbonne Paris Cité, CNRS UMR 7154, 1 rue Jussieu, 75238 Paris Cedex 05, France
2Institut Universitaire de France, Paris, France
Copyright Elsevier
The Moon and the Earth’s mantle share many chemical and isotopic traits, leading to the prevailing theory that they were formed from similar material. Iron is one element that shows apparent differences between the two bodies, with models for the composition of the Moon having ≈1.5 times more FeO (12–14 wt.%), relative to the Earth’s mantle (8 wt.%). This difference is mirrored in their isotope compositions, where lunar mare basalts have δ57Fe (per mille deviation of the 57Fe/54Fe ratio from the IRMM-014 standard) 0.1–0.2‰ higher than peridotitic rocks representative of Earth’s mantle, a feature initially attributed to loss of isotopically light Fe following a giant impact. However, whether basaltic rocks are suitable analogues for the Moon’s composition is debatable in the light of their distinct source regions that reflect the extensive lithological stratification of the lunar mantle. Here, we evaluate the iron isotope composition of the bulk Moon through the study of igneous cumulate rocks of the lunar highlands Magnesium Suite (Mg Suite). The δ57Fe of Mg Suite rocks spans a limited range, from 0.05‰ to 0.10‰, with an average (+0.07±0.02‰+0.07±0.02‰) that overlaps with Earth’s mantle (+0.05±0.01‰+0.05±0.01‰), similarities that extend to their Mg#s, where both reach 0.9. Numerical modelling of iron isotope fractionation during lunar magma ocean crystallisation shows that the Mg Suite should accurately reflect the composition of the bulk Moon, which is therefore +0.07±0.02‰+0.07±0.02‰, indistinguishable from Earth’s mantle but heavier than chondrites (−0.01±0.01‰−0.01±0.01‰). Iron thus behaves coherently with other elements that condense at temperatures higher than Li in showing no isotopic difference between the Earth and Moon, suggesting element depletion on the Moon affected only the more volatile elements. Therefore, there is no cosmochemical basis for iron enrichment or depletion in the bulk Moon relative to the Earth’s mantle, whose composition is an analogue for that of the Moon.
1Zaicong Wang, 1Harry Becker
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2017.05.024]
1Freie Universität Berlin, Institut für Geologische Wissenschaften, Malteserstrasse 74-100, 12249, Berlin, Germany
Copyright Elsevier
Silver and Cu show very similar partitioning behavior in sulfide melt-silicate melt and metal-silicate systems at low and high pressure-temperature (P-T) experimental conditions, implying that mantle melting, fractional crystallization and core-mantle differentiation have at most modest (within a factor of 3) effects on Cu/Ag ratios. For this reason, it is likely that Cu/Ag ratios in mantle-derived magmatic products of planetary bodies reflect that of the mantle and, in some circumstances, also the bulk planet composition. To test this hypothesis, new Ag mass fractions and Cu/Ag ratios in different groups of Martian meteorites are presented and compared with data from chondrites and samples from the Earth’s mantle.
Silver contents in lherzolitic, olivine-phyric and basaltic shergottites and nakhlites range between 1.9 and 12.3 ng/g. The data display a negative trend with MgO content and correlate positively with Cu contents. In spite of displaying variable initial Ɛ143Nd values and representing a diverse spectrum of magmatic evolution and physiochemical conditions, shergottites and nakhlites display limited variations of Cu/Ag ratios (1080±320, 1s, n=14). The relatively constant Cu/Ag suggests limited fractionation of Ag from Cu during the formation and evolution of the parent magmas, irrespectively of whether sulfide saturation was attained or not. The mean Cu/Ag ratio of Martian meteorites thus reflects that of the Martian mantle and constrains its Ag content to 1.9±0.7 ng/g (1s).
Carbonaceous and enstatite chondrites display a limited range of Cu/Ag ratios of mostly 500-2400. Ordinary chondrites show a larger scatter of Cu/Ag up to 4500, which may have been caused by Ag redistribution during parent body metamorphism. The majority of chondrites have Cu/Ag ratios indistinguishable from the Martian mantle value, indicating that Martian core formation strongly depleted Cu and Ag contents, but probably did not significantly change the Cu/Ag ratio of the mantle compared to bulk Mars. Bulk Mars is richer in moderately volatile elements than Earth, however, the Martian mantle displays a much stronger depletion of the moderately volatile elements Cu and Ag, e.g., by a factor of 15 for Cu. This observation is consistent with experimental studies suggesting that core formation at low P-T conditions on Mars led to more siderophile behavior of Cu and Ag than at high P-T conditions as proposed for Earth. In contrast, Cu/Ag ratios of the mantles of Mars and Earth (Cu/AgEarth=3500±1000) display only a difference by a factor of 3, which implies restricted fractionation of Cu and Ag even at high P-T conditions. The concentration data support the notion that siderophile element partitioning during planetary core formation scales with the size of the planetary body, which is particularly important for the differentiation of large terrestrial planets such as Earth. Collectively, the Ag and Cu data on magmatic products from the mantles of Mars and Earth and the data on chondrites confirm experimental predictions and support the limited fractionation of Cu and Ag during planetary core formation and high-temperature magmatic evolution, and probably also in early solar nebular processes.
