Hostname: page-component-77c89778f8-gq7q9 Total loading time: 0 Render date: 2024-07-19T01:09:54.515Z Has data issue: false hasContentIssue false
  • English
  • Français

Extreme chemical variation in complex diamonds from George Creek, Colorado: a SIMS study of carbon isotope composition and nitrogen abundance

Published online by Cambridge University Press:  05 July 2018

I. C. W. Fitzsimons ,
B. Harte ,
I. L. Chinn ,
J. J. Gurney  and
W. R. Taylor
I. C. W. Fitzsimons
Affiliation:
Department of Geology and Geophysics, The University of Edinburgh, The Grant Institute, West Mains Road, Edinburgh EH9 3JW, UK
B. Harte
Affiliation:
Department of Geology and Geophysics, The University of Edinburgh, The Grant Institute, West Mains Road, Edinburgh EH9 3JW, UK
I. L. Chinn
Affiliation:
Department of Geological Sciences, University of Cape Town, Rondebosch 7700, South Africa
J. J. Gurney
Affiliation:
Department of Geological Sciences, University of Cape Town, Rondebosch 7700, South Africa
W. R. Taylor
Affiliation:
Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia
Get access Rights & Permissions [Opens in a new window]

Abstract

Diamonds from George Creek, Colorado, preserve complex intergrowth textures between two major growth generations: homogeneous diamond with yellow-buff cathodoluminescence (CL); and diamond with blue-green CL and local growth zonation. Secondary-ion mass spectrometry (SIMS) has revealed large variations in N concentration and C isotope composition within these diamonds. Even within single stones, N contents and δ13C values can vary from 0 to 750 ppm and 0 to −20‰ respectively. These variations are similar to those recorded elsewhere for entire diamond suites. The CL characteristics correlate directly with N: diamond with yellow-buff CL has uniform N contents, whereas the zoned diamond has bright blue CL bands with high N (50–750 ppm) and dark blue or green CL bands with low N (0–20 ppm). These bands are too narrow (10–5 µm) for analysis by IR spectroscopy. δ13C also varies between the two growth generations in any one diamond plate, and to a lesser extent within these generations, but shows no consistent correlations with either CL or N. The George Creek stones preserve evidence of extreme temporal and/or spatial variations in both δ13C and N concentrations during the period of diamond growth, but the factors controlling N content during diamond growth did not control δ13C.

Keywords

carbon isotopescathodoluminescencediamondnitrogen concentrationSIMS
Type
Research Article
Information
Mineralogical Magazine , Volume 63 , Issue 6 , December 1999 , pp. 857 - 878
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1999

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

*

Present address: School of Applied Geology, Curtin University of Technology, GPO Box U1987, Perth, WA 6845, Australia

References

Bennett, V.C. and DePaolo, D.J. (1987) Proterozoic crustal history of the western United States as determined by neodymium isotopic mapping. Geol. Soc. Am. Bull., 99, 674–85.2.0.CO;2>CrossRefGoogle Scholar
Bertrand, P. and Mercier, J.-C.C. (1985) The mutual solubility of coexisting ortho- and clinopyroxene: toward an absolute geothermometer for the natural system? Earth Planet. Sci. Lett., 76, 109–22.CrossRefGoogle Scholar
Boyd, S.R. and Pillinger, C.T. (1994) A preliminary study of 15N/14N in octahedral growth form diamonds. Chem. Geol., 116, 43–59.CrossRefGoogle Scholar
Boyd, S.R., Mattey, D.P., Pillinger, C.T., Milledge, H.J., Mendelssohn, M. and Seal, M. (1987) Multiple growth events during diamond genesis: an integrated study of carbon and nitrogen isotopes and nitrogen aggregation state in coated stones. Earth Planet. Sci. Lett., 86, 341–53.CrossRefGoogle Scholar
Boyd, S.R., Pillinger, C.T., Milledge, H.J., Mendelssohn, M.J. and Seal, M. (1988) Fractionation of nitrogen isotopes in a synthetic diamond of mixed crystal habit. Nature, 331, 604–7.CrossRefGoogle Scholar
Boyd, S.R., Pillinger, C.T., Milledge, H.J., Mendelssohn, M.J. and Seal, M. (1992) C and N isotopic composition and the infrared absorption spectra of coated diamonds: evidence for the regional uniformity of CO2-H2O rich fluids in lithospheric mantle. Earth Planet. Sci. Lett., 109, 633–44.CrossRefGoogle Scholar
Boyd, S.R., Pineau, F. and Javoy, M. (1994) Modelling the growth of natural diamonds. Chem. Geol., 116, 29–42.CrossRefGoogle Scholar
Bulanova, G.P. (1995) The formation of diamond. J. Geochem. Explor., 53, 1–23.CrossRefGoogle Scholar
Cartigny, P., Boyd, S.R., Harris, J.W. and Javoy, M. (1997) Nitrogen isotopes in peridotitic diamonds from Fuxian, China: the mantle signature. Terra Nova, 9, 175–179.CrossRefGoogle Scholar
Chinn, I.L. (1995) A study of unusual diamonds from the George Creek K1 kimberlite dyke, Colorado. Ph.D. thesis (unpubl.), University of Cape Town.Google Scholar
Deines, P. (1980) The carbon isotopic composition of diamonds: relationship to diamond shape, color, occurrence and vapor composition. Geochim. Cosmochim. Acta, 44, 943–61.CrossRefGoogle Scholar
Deines, P., Gurney, J.J. and Harris, J.W. (1984) Associated chemical and carbon isotopic composition variations in diamonds from Finsch and Premier kimberlite, South Africa. Geochim. Cosmochim. Acta, 48, 325–42.CrossRefGoogle Scholar
Deines, P., Harris, J.W. and Gurney, J.J. (1987) Carbon isotopic composition, nitrogen content and inclusion composition of diamonds from the Roberts Victor kimberlite, South Africa: evidence for 13C depletion in the mantle. Geochim. Cosmochim. Acta, 51, 1227–43.CrossRefGoogle Scholar
Deines, P., Harris, J.W., Spear, P.M. and Gurney, J.J. (1989) Nitrogen and 13C content of Finsch and Premier diamonds and their implications. Geochim. Cosmochim. Acta, 53, 1367–78.CrossRefGoogle Scholar
Deines, P., Harris, J.W. and Gurney, J.J. (1991) The carbon isotopic composition and nitrogen content of lithospheric and asthenospheric diamonds from the Jagersfontein and Koffiefontein kimberlite, South Africa. Geochim. Cosmochim. Acta, 55, 2615–25.CrossRefGoogle Scholar
Deines, P., Harris, J.W. and Gurney, J.J. (1997) Carbon isotope ratios, nitrogen content and aggregation state, and inclusion chemistry of diamonds from Jwaneng, Botswana. Geochim. Cosmochim. Acta, 61, 3993–4005.CrossRefGoogle Scholar
Eggler, D.H., Meen, J.K., Welt, F., Dudas, F.O., Furlong, K.P., McCallum, M.E. and Carlson, R.W. (1988) Tectonomagmatism of the Wyoming Province. Colo. Sch. Mines Q., 83, 25–40.Google Scholar
Eiler, J.M., Valley, J.W., Graham, C.M. and Baumgartner, L.P. (1995) Ion microprobe evidence for the mechanisms of stable isotope retrogression in high-grade metamorphic rocks. Contrib. Mineral. Petrol., 118, 365–78.CrossRefGoogle Scholar
Ellis, D.J. and Green, D.H. (1979) An experimental study of the effect of Ca upon garnet-clinopyroxene Fe-Mg exchange equilibria. Contrib. Miner. Petrol., 71, 13–22.CrossRefGoogle Scholar
Evans, T. (1992) Aggregation of nitrogen in diamond. In The properties of natural and synthetic diamond (Field, J.E., ed.). Academic Press, London, pp. 259–90.Google Scholar
Evans, T. and Harris, J.W. (1989) Nitrogen aggregation, inclusion equilibration temperatures and the age of diamonds. In Kimberlites and related rocks, vol. 2 (Ross, J., ed.). Geological Society of Australia, Spec. Publ., 14, Blackwell Scientific, Melbourne, pp. 1001–6.Google Scholar
Fitzsimons, I.C.W., Harte, B. and Clark, R.M. (in press) SIMS stable isotope measurement: counting statistics and analytical precision. Mineral. Mag. Google Scholar
Galimov, E.M. (1991) Isotope fractionation related to kimberlite magmatism and diamond formation. Geochim. Cosmochim. Acta, 55, 1697–708.CrossRefGoogle Scholar
Harris, J.W. (1987) Recent physical, chemical, and isotopic research of diamond. In Mantle xenoliths (Nixon, P.H., ed.). John Wiley & Sons, Chichester, pp. 477–500.Google Scholar
Harte, B. and Otter, M. (1992) Carbon isotope measurements on diamonds. Chem. Geol., 101, 177–83.Google Scholar
Harte, B., Fitzsimons, I.C.W., Harris, J.W. and Otter, M.L. (1999) Carbon isotope ratios and nitrogen abundances in relation to cathodoluminescence characteristics for some diamonds from the Kaapvaal Province, S. Africa. Mineral. Mag., 63, 829–56.CrossRefGoogle Scholar
Helmstaedt, H.H. and Gurney, J.J. (1995) Geotectonic controls of primary diamond deposits: implications for area selection. J. Geochem. Explor., 53, 125–44.CrossRefGoogle Scholar
Hoffman, P.F. (1990) Geological constraints on the origin of the mantle beneath the Canadian shield. Phil. Trans. R. Soc. London, A331, 523–32.Google Scholar
Javoy, M., Pineau, F. and Demaiffe, D. (1984) Nitrogen and carbon isotopic composition in the diamonds of Mbuji Mayi, Zaïre. Earth Planet. Sci. Lett., 68, 399–412.CrossRefGoogle Scholar
Kanda, H. and Yamaoka, S. (1993) Inhomogeneous distribution of nitrogen impurities in {111} growth sectors of high pressure synthetic diamond. Diamond and Related Materials, 2, 1420–3.CrossRefGoogle Scholar
Karlstrom, K.E. and Houston, R.S. (1984) The Cheyenne Belt: analysis of a Proterozoic suture in southern Wyoming. Precambrian Res., 25, 415–46.CrossRefGoogle Scholar
Kirkley, M.B., Gurney, J.J., Otter, M.L., Hill, S.J. and Daniels, L.R. (1991) The application of C isotope measurements to the identification of the sources of C in diamonds: a review. Appl. Geochem., 6, 477–94.CrossRefGoogle Scholar
Lang, A.R. (1974) On the growth-sectorial dependence of defects in natural diamonds. Proc. R. Soc. London, A340, 233–48.Google Scholar
Nickel, K.G. and Green, D.H. (1985) Empirical geothermobarometry for garnet peridotites and implications for the nature of the lithosphere, kimberlites and diamonds. Earth Planet. Sci. Lett., 73, 158–70.CrossRefGoogle Scholar
Reed, J.C., Ball, T.T., Farmer, G.L. and Hamilton, W.B. (1993) A broader view. In The geology of North America, vol. C-2, Precambrian: Conterminous U.S. (Reed, J.C., et al., eds.). Geological Society of America, Boulder, Colorado, pp. 597–636.Google Scholar
Slodzian, G. (1980) Microanalyzers using secondary ion emission. Adv. Electronics Electron Phys. Suppl., 13B, 1–44.Google Scholar
Smith, M.P. and Yardley, B.W.D.(1996) The boron isotopic composition of tourmaline as a guide to fluid processes in the southwestern England orefield: an ion microprobe study. Geochim. Cosmochim. Acta, 60, 1415–27.CrossRefGoogle Scholar
Swart, P.K., Pillinger, C.T., Milledge, H.J. and Seal, M. (1983) Carbon isotopic variation within individual diamonds. Nature, 303, 793–5.CrossRefGoogle Scholar
Taylor, W.R., Jaques, A.L. and Ridd, M. (1990) Nitrogen-defect aggregation characteristics of some Australasian diamonds: time-temperature constraints on the source regions of pipe and alluvial diamonds. Amer. Mineral., 75, 1290–310.Google Scholar
Taylor, W.R., Canil, D. and Milledge, H.J. (1996) Kinetics of Ib to IaA nitrogen aggregation in diamond. Geochim. Cosmochim. Acta, 60, 4725–33.CrossRefGoogle Scholar
Valley, J.W. and Graham, C.M. (1991) Ion microprobe analysis of oxygen isotope ratios in granulite facies magnetites: diffusive exchange as a guide to cooling history. Contrib. Mineral. Petrol., 109, 38–52.CrossRefGoogle Scholar
van Heerden, L.A., Gurney, J.J. and Deines, P. (1995) The carbon isotopic composition of harzburgitic, lherzolitic, websteritic and eclogitic paragenesis diamonds from southern Africa: a comparison of genetic models. S. Afr. J. Geol., 98, 119–25.Google Scholar
Zinner, E., Ming, T. and Anders, E. (1989) Interstellar SiC in the Murchison and Murray meteorites: isotopic composition of Ne, Xe, Si, C and N. Geochim. Cosmochim. Acta, 53, 3273–90.CrossRefGoogle Scholar