Hostname: page-component-586b7cd67f-l7hp2 Total loading time: 0 Render date: 2024-11-26T07:19:56.504Z Has data issue: false hasContentIssue false
  • English
  • Français

Trace element composition and cathodoluminescence properties of southern African kimberlitic zircons

Published online by Cambridge University Press:  05 July 2018

E. A. Belousova ,
W. L. Griffin  and
N. J. Pearson
E. A. Belousova
Affiliation:
National Key Centre for Geochemical Evolution and Metallogeny of Continents, School of Earth Sciences, Macquarie University, Sydney, NSW 2109, Australia
W. L. Griffin
Affiliation:
National Key Centre for Geochemical Evolution and Metallogeny of Continents, School of Earth Sciences, Macquarie University, Sydney, NSW 2109, Australia CSIRO Exploration and Mining, P.O. Box 136, North Ryde, NSW 2113, Australia
N. J. Pearson
Affiliation:
National Key Centre for Geochemical Evolution and Metallogeny of Continents, School of Earth Sciences, Macquarie University, Sydney, NSW 2109, Australia
Get access Rights & Permissions [Opens in a new window]

Abstract

Zircon frequently occurs as a minor mineral in kimberlites, and is recognised as a member of a suite of mantle-derived megacryst minerals. Cathodoluminescence (CL) microscopy and laser ablation ICPMS analysis were used to study the internal structure and chemical composition of zircon crystals from southern African kimberlites. Zoning revealed by CL ranges from fine oscillatory to broad homogeneous cores and overgrowths. The ICPMS data show that kimberlite zircons have distinctive trace element contents, with well defined ranges for REE, Y, U, Th, P and some other trace elements. Both low REE contents (ΣREE < 50 ppm), and distinctive chondrite-normalised REE patterns with low and flat HREE are characteristic of kimberlite zircons. Samples or zones with yellow CL have higher Th, U, Y, and REE than those with blue-violet CL. Variations in the concentrations of a range of trace elements lead to different amounts of lattice defects, creating the possibility for different levels of direct excitation of luminescence centres, and therefore different CL colours. The distinctive CL and compositional features described here can rapidly identify kimberlite zircons in prospecting samples taken during exploration for kimberlite bodies.

Keywords

zirconkimberlitecathodoluminescencetrace elementssouthern Africa
Type
Research Article
Information
Mineralogical Magazine , Volume 62 , Issue 3 , June 1998 , pp. 355 - 366
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1998

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.)

References

Ahrens, L.H., Cherry, R.D. and Erlank, A.J. (1967) Observations on the Th-U relationship in zircons from granitic rocks and from kimberlites. Geochim. Cosmochim. Acta, 31, 2379–87.CrossRefGoogle Scholar
Gavrilenko, V.V. and Sakhonenok, V.V. (1986) Basis of Geochemistry of Rare Lithophylic Metals. Leningrad University, 1–172 (in Russian).Google Scholar
Guo, J., O’Reilly, S.Y. and Griffin, W.L. (1996) Zircon inclusions in corundum megacrysts I: trace element geochemistry and clues to the origin of corundum megacrysts in alkali basalts. Geochim. Cosmochim. Acta, 60, 2347–63.CrossRefGoogle Scholar
Jensen, B.B. (1973). Patterns of trace element partitioning. Geochim. Cosmochim. Acta, 37, 2227–42.CrossRefGoogle Scholar
Kabanova, Ye.S., Skosyrova, M.V. and Solodov, N.A. (1982) Geochemistry and Mineralogy of Tantalum and Niobium. Moscow, 1–175 (in Russian).Google Scholar
Krasnobayev, A.A. (1979) Mineralogical-geochemical features of zircons from kimberlites and problems of their origin. Internat. Geology Rev., 22, 1199–209.CrossRefGoogle Scholar
Kresten, P., Fels, P. and Berggren, G. (1975) Kimberlite zircons – a possible aid in prospecting for kimberlites. Mineral. Deposita(Berl.), 10, 47–56.CrossRefGoogle Scholar
Lyakhovich, V.V. (1996) Zircons in diamond-bearing rocks. Trans. (Doklady) Russian Acad. Sci./Earth Sci. Sections, 347, 179–99.Google Scholar
Marfunin, A.S. (1979) Spectroscopy. Luminescence and Radiation Centers in Minerals(Translated by Schiffer, V.V.). Springer-Verlag, Berlin, Heidelberg, New-York, 1–347.CrossRefGoogle Scholar
Moore, R.O., Griffin, W.L., Gurney, J.J., Ryan, C.G., Cousens, D.R., Sie, S.H. and Suter, G.F. (1992) Trace element geochemistry of ilmenite megacrysts from the Monastery kimberlite, South Africa. Lithos, 29, 1–18.CrossRefGoogle Scholar
Norman, M.D., Pearson, N.J., Sharma, A. and Griffin, W.L. (1996) Quantitative analysis of trace elements in geological materials by laser ablation ICPMS: instrumental operating conditions and calibration values of NIST glasses. Geostandards Newsletter, 20, 247–61.CrossRefGoogle Scholar
Remond, G., Blanc, P., Cesbron, F., Ohnenstetter, D. and Rouer, O. (1996) Cathodoluminescence of rare earth doped zircons: Part II: relationship between the distribution of the doping elements and the contrasts of CL images. Scanning Microscopy, suppl. 9, 57–76.Google Scholar
Shannon, R.D. (1976) Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Crystallogr., A32, 751.CrossRefGoogle Scholar
Shnyukov, S.E., Cheburkin, A.K. and Andreev, A.V. (1989) Geochemistry of wide-spread coexisting accessory minerals and their role in investigation of endogenetic and exogenetic processes. Geol. J., 2, 107–14 (in Russian).Google Scholar
Taylor, S.R. and McLennan, S.M. (1985) The Continental Crust: its Composition and Evolution. Blackwell Sci. Publ., Oxford.Google Scholar
Wiedenbeck, M., Alle, P., Corfu, F., Griffin, W.L., Meier, M., Oberli, F., Von Quart, A., Roddick, J.C. and Spiegel, W. (1995) Three natural zircon standards for U-Th-Ph, Lu-Hf, trace element and REEanalyses. Geostandards Newsletter, 19, 1–23.CrossRefGoogle Scholar