Fisenko, A. V.

Pillinger, C. T.

Semjonova, L. F.

Verchovsky, A. B.

English

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Open Research OnlineThe Open University’s repository of research publicationsand other research outputsCarbon, nitrogen and noble gases in diamond separatesfrom the Novo-Urei ureiliteConference or Workshop ItemHow to cite:Fisenko, A. V.; Verchovsky, A. B.; Semjonova, L. F. and Pillinger, C. T. (2004). Carbon, nitrogen and noblegases in diamond separates from the Novo-Urei ureilite. In: 67th Annual Meeting of the Meteoritical Society, 2-6 Aug2004, Rio de Janeiro, Brazil.For guidance on citations see FAQs.c© [not recorded]Version: [not recorded]Link(s) to article on publisher’s website:http://www.lpi.usra.edu/meetings/metsoc2004/pdf/5159.pdfCopyright and Moral Rights for the articles on this site are retained by the individual authors and/or other copyrightowners. For more information on Open Research Online’s data policy on reuse of materials please consult the policiespage.oro.open.ac.ukCARBON, NITROGEN AND NOBLE GASES IN DIA-MOND SEPARATES FROM THE NOVO-UREI UREILITE.  A. V. Fisenko1, A. B. Verchovsky2, L. F. Semjonova1 and C.T. Pillinger2. 1Vernadsky Institute of Geochemistry and Analytycal Chemistry RAS, Moscow, Russia, anatolii@fis.home.chg.ru. The Open University, Milton Keynes, UK.  The origin of diamond in ureilites is still debating. There are two the most popular explanations: (1) as a result of shock trans-formation from graphite caused by meteorite impact in the parent bodies [1-4], and (2) in a CVD process in the solar nebula [5-7]. We isolated a sample strongly enriched with diamond from the Novo-Urei ureilite and separated it into two density fractions in a heavy liquid at 2.9 g.cm-3. C, N, Ar and Xe have been ana-lyzed simultaneously in the fractions by means of stepped com-bustion. Purity of the diamonds have been confirmed by Raman spectroscopy showing practical absence of graphite lines but sur-prisingly double picks for diamond in the range of 1315-1335 cm-1 that seems not to be observed in diamonds from other ureilites.       It has been found that concentration of N and noble gases in the less dense fraction (DNU-1) is ~1.5 times higher, than in the complimentary sediment (DNU-2). We believe the difference is due to the presence of aggregates with relatively low density made of smaller grains in DNU-1 compared to DNU-2 which consists mostly of single grains. Isotopic compositions of C ( 13C~-2‰), N ( 15N~-95‰) and noble gases as well as the ele-mental composition of the latter are similar in both fractions and to other diamonds analyzed before [8]. The obtained data to-gether with published before, allow us to conclude that ureilite diamonds are likely formed as a result of shock transformation from graphite and amorphous carbon in the ureilites parent bod-ies. We also suggest that: (1) Carbonaceous material in the dia-mond-free ureilite ALH 78019 [9] seems to be contaminated with terrestrial atmospheric nitrogen during weathering since it is en-riched with the nitrogen compared to other ureilites (Fig.).  Therefore it does not show the light N signature normally ob-served in the ureilite diamonds. (2) The source of the light N in the ureilites might be presolar nanodiamods ( 15N up to -350‰) that could be present in the carbonaceous material – precursor of the ureilites carbon.  Element ratios in ureilites. 1- present study; 2, 3 – carbon separates from Antarctic ureilites [10] for bulk (2) and magnetic fractions (3); 4, 5 – HF-HCl fractions of ALH 78019 [9] for total release (4) and without the first 300oC step (5). References: [1] Lipschutz M.E. 1964. Science 143: 1431-1434. [2] Vdovykin G.P. 1970. Meteoritika 30: 95-103. [3] Nakamuta Y., Aoki Y. 2000. Meteorit. Planet. Sci. 35: 487-493. [4] Valter А.А. et al. 2003. Geochimia N10: 1027-1035. [5] Matsuda J., Nagao K. 1989. Geochim. Cosmochim. Acta 53: 1117-1121. [6] Matsuda J. et al. 1991. Geochim. Cosmochim. Acta 55: 2011-2023. [7] Matsuda J., et al. 1995. Geochim. Cosmochim. Acta 59: 4939-4949. [8] Russell S.S. et al. 1993. 24th Lunar and Planet. Sci. Conf. pp. 1221-1222. [9] Rai V.K., et al. 2002. Meteorit. Planet. Sci 37: 1045-1055. [10] Yamamoto T. et al. 1998. Meteorit. Planet. Sci 33: 857-870. 0 1 2 3 4 5 6 7 8 902468 - 1 - 2- 3 - 4- 5(N / 36Ar) / 103, mol / mol(132Xe / 36Ar) x 10367th Annual Meteoritical Society Meeting (2004) 5159.pdf

Carbon, nitrogen and noble gases in diamond separates from the Novo-Urei ureilite

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Carbon, nitrogen and noble gases in diamond separates from the Novo-Urei ureilite

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