Geology of Ore Deposits

, Volume 51, Issue 7, pp 608–616

Chemical composition of nyerereite and gregoryite from natrocarbonatites of Oldoinyo Lengai volcano, Tanzania

  • A. N. Zaitsev
  • J. Keller
  • J. Spratt
  • T. E. Jeffries
  • V. V. Sharygin
Minerals and Parageneses of Minerals

Abstract

Alkali carbonates nyerereite, ideally Na2Ca(CO3)2 and gregoryite, ideally Na2CO3, are the major minerals in natrocarbonatite lavas from Oldoinyo Lengai volcano, northern Tanzania. They occur as pheno- and microphenocrysts in groundmass consisting of fluorite and sylvite; nyerereite typically forms prismatic crystals and gregoryite occurs as round, oval crystals. Both minerals are characterized by relatively high contents of various minor elements. Raman spectroscopy data indicate the presence of sulfur and phosphorous as (SO4)2− and (PO4)3− groups. Microprobe analyses show variable composition of both nyerereite and gregoryite. Nyerereite contains 6.1–8.7 wt % K2O, with subordinate amounts of SrO (1.7–3.3 wt %), BaO (0.3–1.6 wt %), SO3 (0.8–1.5 wt %), P2O5 (0.2–0.8 wt %) and Cl (0.1–0.35 wt %). Gregoryite contains 5.0–11.9 wt % CaO, 3.4–5.8 wt % SO3, 1.3–4.6 wt % P2O5, 0.6–1.0 wt % SrO, 0.1–0.6 wt % BaO and 0.3–0.7 wt % Cl. The content of F is below detection limits in nyerereite and gregoryite. Laser ablation ICP-MS analyses show that REE, Mn, Mg, Rb and Li are typical trace elements in these minerals. Nyerereite is enriched in REE (up to 1080 ppm) and Rb (up to 140 ppm), while gregoryite contains more Mg (up to 367 ppm) and Li (up to 241 ppm) as compared with nyerereite.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    J. W. Anthony, R. A. Bideaux, K. W. Bladh, and M. C. Nichols, Handbook of Mineralogy, Vol. V: Boraties, Carbonates, Sulfates (Mineral Data Publishing, Tuscon, 2003).Google Scholar
  2. 2.
    A. Arakcheeva and G. Chapuis, “A Reinterpretation of the Phase Transitions in Na2CO3,” Acta Cryst. B61, 601–607 (2005).Google Scholar
  3. 3.
    M. E. Böttcher and C. Reutel, “The Raman Spectrum of α-Na2Ca(CO3)2,” J. Raman Spec. 27, 859–86 (1996).CrossRefGoogle Scholar
  4. 4.
    A. A. Church and A. P. Jones, “Hollow Natrocarbonatite Lapilli from the 1992 Eruption of Oldoinyo Lengai, Tanzania,” J. Geol. Soc. London, 151, pp. 59–63 (1994).CrossRefGoogle Scholar
  5. 5.
    A. A. Church and A. P. Jones, “Silicate-Carbonate Immiscibility at Oldoinyo Lengai,” J. Petrol. 36, 869–889 (1995).Google Scholar
  6. 6.
    J. B. Dawson, “The Geology of Oldoinyo Lengai,” Bull. Volcan. 24, 349–387 (1962).CrossRefGoogle Scholar
  7. 7.
    J. B. Dawson, “Oldoinyo Lengai: Active Volcano with Lava-Flows of Natrocarbonatites,” in Carbonatites (Carbonaties, Wiley, Ney York, 1966; Mir, Moscow, 1969), pp. 169–181.Google Scholar
  8. 8.
    J. B. Dawson, H. Pinkerton, G. E. Norton, D. M. Pyle, P. Browning, D. Jackson, and A. E. Fallick, “Petrology and Geochemistry of Oldoinyo Lengai Lavas Extruded in November 1988: Magma Source, Ascent and Crystallization,” in Carbonatite Volcanism. Oldoinyo Lengai and the Petrogenesis of Natrocarbonatites (Springer, Berlin, 1995), pp. 47–69.Google Scholar
  9. 9.
    M. J. Genge, M. Balme, and A. P. Jones, “Salt-Bearing Fumaroles Deposits in the Summit Crater of Oldoinyo Lengai, Northern Tanzania: Interactions between Natrocarbonatite Lava and Meteoric Water,” J. Volcan. Geotherm. Res. 106, 111–122 (2001).CrossRefGoogle Scholar
  10. 10.
    J. Gittnins and D. McKie, “Alkalic Carbonatite Magmas: Oldoinyo Lengai and Its Wider Applicability,” Lithos. 13, 213–215 (1980).CrossRefGoogle Scholar
  11. 11.
    Yu. L. Kapustin and A. I. Polyakov, “Volcanic Carbonatites of the Eastern Africa,” Zap. Vsesoyuzn. Mineral. O-va 111(6), 639–655 (1982).Google Scholar
  12. 12.
    J. Keller and M. Krafft, “Effusive Natrocarbonatite Activity of Oldoinyo Lengai, June 1988,” Bull. Volcan. 52, 629–645 (1990).CrossRefGoogle Scholar
  13. 13.
    J. Keller and A. N. Zaitsev, “Calciocarbonatite Dykes at Oldoinyo Lengai, Tanzania: The Fate of Natrocarbonatite,” Canad. Miner. 44, 857–876 (2006).CrossRefGoogle Scholar
  14. 14.
    U. Koberski and J. Keller, “Cathodoluminescence Observations of Natrocarbonatites and Related Peralkaline Nephelinites at Oldoinyo Lengai,” in Carbonatite Volcanism. Oldoinyo Lengai and the Petrogensis of Natrocarbonatites (Springer, Berlin, 1995), pp. 87–99.Google Scholar
  15. 15.
    V. G. Krivovichev, Dictionary of Mineral Species (SOLO, St. Petersburg, 2006) [in Russian].Google Scholar
  16. 16.
    D. McKie and E. J. Frankis, “Nyerereite: A New Volcanic Carbonate Mineral from Oldoinyo Lengai, Tanzania,” Ztschr. Krist. 145, 73–95 (1977).Google Scholar
  17. 17.
    H. Meekes, Th. Rasing, P. Wyder, A. Janner, and T. Janssen, “Raman and Infrared Spectra of the Incommensurate Crystal Na2CO3,” Phys. Rev. B. 34, 4240–4254 (1986).CrossRefGoogle Scholar
  18. 18.
    R. H. Mitchell, “Carbonate-Carbonate Immiscibility Neighborite and Potassium Iron Sulphide in Oldoinyo Lengai Natrocarbonatite,” Miner. Mag. 61, 779–789 (1997).CrossRefGoogle Scholar
  19. 19.
    R. H. Michell, “Mineralogy of Stalactites Formed by Subaerial Weathering of Natrocarbonatite Hornitos at Oldoinyo Lengai, Tanzania,” Miner. Mag. 70, 437–444 (2006a).CrossRefGoogle Scholar
  20. 20.
    R. H. Mitchell, “Sylvite and Fluorite Microcrysts, and Fluorite-Nyerereite Intergrowths from Natrocarbonatite, Oldoinyo Lengai, Tanzania,” Miner. Mag. 70, 103–114 (2006b).CrossRefGoogle Scholar
  21. 21.
    R. H. Michell and F. Belton, “Niocalite-Cuspidine Solid Solution and Manganoan Monticellite from Matrocarbonatite, Oldoinyo Lengai, Tanzania,” Miner. Mag. 68, 787–799 (2004).CrossRefGoogle Scholar
  22. 22.
    E. H. Nickel and M. C. Nichols, Mineral Reference Manual (Van Nostrand Reinhold, New York, 1991).Google Scholar
  23. 23.
    T. D. Peterson, “Petrology and Genesis of Natrocarbonatite,” Contrib. Miner. Petrol. 105, 143–155 (1990).CrossRefGoogle Scholar
  24. 24.
    H. Pinkerton, G. E. Norton, J. B. Dawson, and D. M. Pyle, “Field Observations and Measurements of the Physical Properties of Oldoinyo Lengai Alkali Carbonatite Lavas, November 1988,” in Carbonatite Volcanism. Oldoinyo Lengai and the Petrogenesis of Natrocarbonatites (Springer, Berlin, 1995), pp. 23–36.Google Scholar
  25. 25.
    H. Strunz and E. H. Nickel, Strunz Mineralogical Tables. Chemical-Structural Mineral Classification System, 9th Edit., (Schweizerbart, Stuttgart, 2001).Google Scholar
  26. 26.
    A. N. Zaitsev and J. Keller, “Mineralogical and Chemical Transformation of Oldoinyo Lengai Natrocarbonatite, Tanzania,” Lithos 91, 191–207 (2006).CrossRefGoogle Scholar

Copyright information

© Pleiades Publishing, Ltd. 2009

Authors and Affiliations

  • A. N. Zaitsev
    • 1
  • J. Keller
    • 2
  • J. Spratt
    • 3
  • T. E. Jeffries
    • 3
  • V. V. Sharygin
    • 4
  1. 1.Department of MineralogySt. Petersburg State UniversitySt. PetersburgRussia
  2. 2.Mineralogisch-Geochemisches InstitutUniversitat FreiburgFreiburgGermany
  3. 3.Department of MineralogyThe Natural History MuseumLondonUK
  4. 4.Institute of Geology and Mineralogy, Siberian BranchRussian Academy of SciencesNovosibirskRussia

Personalised recommendations