In situ micro‐Raman and X‐ray diffraction study of diamonds and petrology of the new ureilite UAE 001 from the United Arab Emirates |
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| Authors: | Dominik C HEZEL Leonid DUBROVINSKY Lutz NASDALA Jean CAUZID Alexandre SIMIONOVICI Marko GELLISSEN Thorbjörn SCHÖNBECK |
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| Institution: | 1. Universit?t zu K?ln, Institut für Geologie und Mineralogie, Zülpicherstr. 49b, D‐50674 K?ln, Germany;2. Department of Mineralogy, Natural History Museum, Cromwell Road, London, SW7 5BD, UK;3. Bayerisches Geoinstitut, Universit?t Bayreuth, D‐95440 Bayreuth, Germany;4. Johannes Gutenberg‐Universit?t Mainz, Institut für Geowissenschaften, Becherweg 21, D‐55099 Mainz, Germany;5. Universit?t Wien, Institut für Mineralogie und Kristallographie, Althanstra?e 14, A‐1090 Wien, Austria;6. ESRF, 6 rue Jules Horowitz, BP220, 38043 Grenoble Cedex, France;7. Laboratoire de Géophysique Interne et Tectonophysique, OSUG, BP 53, 38041 Grenoble, France |
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| Abstract: | Abstract— A new olivine‐pigeonite ureilite containing abundant diamonds and graphite was found in the United Arab Emirates. This is the first report of a meteorite in this country. The sample is heavily altered, of medium shock level, and has a total weight of 155 g. Bulk rock, olivine (Fo79.8–81.8) and pyroxene (En73.9–75.2, Fs15.5–16.9, Wo8.8–9.5) compositions are typical of ureilites. Olivine rims are reduced with Fo increasing up to Fo96.1–96.8. Metal in these rims is completely altered to Fehydroxide during terrestrial weathering. We studied diamond and graphite using micro‐Raman and in situ synchrotron X‐ray diffraction. The main diamond Raman band (LO = TO mode at ?1332 cm?1) is broadened when compared to well‐ordered diamond single crystals. Full widths at half maximum (FWHM) values scatter around 7 cm?1. These values resemble FWHM values obtained from chemical vapor deposition (CVD) diamond. In situ XRD measurements show that diamonds have large grain sizes, up to >5 μm. Some of the graphite measured is compressed graphite. We explore the possibilities of CVD versus impact shock origin of diamonds and conclude that a shock origin is much more plausible. The broadening of the Raman bands might be explained by prolonged shock pressure resulting in a transitional Raman signal between experimentally shock‐produced and natural diamonds. |
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