¹Ohgo S, ¹Nishido H, ¹Ningawa K
¹Department of Biosphere–Geosphere Science, Okayama University of Science 2) Department of Applied Physics, Okayama University of Science

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Reference
Ohgo S, Nishido H, Ningawa K (2015) Cathodoluminescence characterization of enstatite. Journal of Mineralogical and Petrological Sciences 110, 241-246
Link to Article [http://doi.org/10.2465/jmps.150713b]

¹Robin M. Canup,^1,2Channon Visscher,¹Julien Salmon,³Bruce Fegley Jr
¹Planetary Sciences Directorate, Southwest Research Institute, Boulder, Colorado 80302, USA
²Chemistry and Planetary Sciences, Dordt College, Sioux Center, Iowa 51250, USA
³Department of Earth and Planetary Sciences and McDonnell Center for Space Sciences, Washington University, St Louis, Missouri 63130, USA

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

Reference
Canup RM, Visscher C, Salmon J, Fegley Jr B (2015) Lunar volatile depletion due to incomplete accretion within an impact-generated disk. Nature Geoscience 8, 918 – 921
Link to Article [doi:10.1038/ngeo2574]

¹P. Bonnand, ²H.M. Williams, ^3,4I.J. Parkinson, ¹B.J. Wood, ¹A.N. Halliday
¹Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, OX1 3AN, United Kingdom
²Department of Earth Sciences, Durham University, Sciences Labs, Durham, DH1 3LE, United Kingdom
³School of Earth Sciences, University of Bristol, Bristol, BS8 1RJ, United Kingdom
⁴Department of Environment, Earth and Ecosystems, CEPSAR, The Open University, Walton Hall, Milton Keynes, MK7 6AA, United Kingdom

We present new mass independent and mass dependent Cr isotope compositions for meteorites measured by double spike thermal ionisation mass spectrometry. Small differences in both mass independent 53Cr and 54Cr relative to the Bulk Silicate Earth are reported and are very similar to previously published values. Carbonaceous chondrites are characterised by an excess in 54Cr compared to ordinary and enstatite chondrites which make mass independent Cr isotopes a useful tool for distinguishing between meteoritic groups. Mass dependent stable Cr isotope compositions for the same samples are also reported. Carbonaceous and ordinary chondrites are identical within uncertainty with average δ53Crδ53Cr values of −0.118±0.040‰−0.118±0.040‰ and −0.143±0.074‰−0.143±0.074‰ respectively. The heaviest isotope compositions are recorded by an enstatite chondrite and a CO carbonaceous chondrite, both of which have relatively reduced chemical compositions implying some stable Cr isotope fractionation related to redox processes in the circumstellar disk. The average δ53Crδ53Cr values for chondrites are within error of the estimate for the Bulk Silicate Earth (BSE) also determined by double spiking. The lack of isotopic difference between chondritic material and the BSE provides evidence that Cr isotopes were not fractionated during core formation on Earth. A series of high-pressure experiments was also carried out to investigate stable Cr isotope fractionation between metal and silicate and no demonstrable fractionation was observed, consistent with our meteorites data. Mass dependent Cr isotope data for achondrites suggest that Cr isotopes are fractionated during magmatic differentiation and therefore further work is required to constrain the Cr isotopic compositions of the mantles of Vesta and Mars.

Reference
Bonnand P,Williams HM, Parkinson IJ,Wood BJ,Halliday AN (2016) Stable chromium isotopic composition of meteorites and metal–silicate experiments: Implications for fractionation during core formation. Earth and Planetary Science Letters 435, 14–21
Link to Article [doi:10.1016/j.epsl.2015.11.026]
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