Hostname: page-component-848d4c4894-tn8tq Total loading time: 0 Render date: 2024-06-27T19:20:01.907Z Has data issue: false hasContentIssue false
  • English
  • Français

1966 ash eruption of the carbonatite volcano Oldoinyo Lengai: mineralogy of lapilli and mixing of silicate and carbonate magmas

Published online by Cambridge University Press:  05 July 2018

J. B. Dawson ,
J. V. Smith  and
I. M. Steele
J. B. Dawson
Affiliation:
Department of Geology and Geophysics, University of Edinburgh, West Mains Road, Edinburgh EH9 3JW
J. V. Smith
Affiliation:
Department of the Geophysical Sciences, University of Chicago, Illinos 60637, U.S.A.
I. M. Steele
Affiliation:
Department of the Geophysical Sciences, University of Chicago, Illinos 60637, U.S.A.
Get access Rights & Permissions [Opens in a new window]

Abstract

Lapilli from the August 1966 eruption of the carbonatite volcano Oldoinyo Lengai consist of carbonate-cemented aggregates of (i) mono- and poly-mineralic fragments of ijolitic rocks, (ii) single grains and clusters of euhedral nepheline, Ti-andradite, and Ti-magnetite, and (iii) corroded pyroxene and wollastonite grains surrounded by coronas containing combeite, melilite, Ca-silicates (possibly larnite and rankinite), and rounded bodies of submicrometre intergrowths with complex bulk compositions dominated by Na,K,Ca-phosphate-carbonate and alkali-iron-sulphide-carbonate. The (ii,iii) materials, together with abundant Na-carbonate, sylvite and fluorite occurring as cement and shells in the lapilli, are attributed to mixing and incomplete reaction of ijolite and carbonatite magmas during the explosive eruption. The rounded submicrometre intergrowths are interpreted as the quench products of two types of immiscible liquids whose properties should be studied by controlled synthesis.

Keywords

carbonatitesilicatecarbonatemagmasOldoinyo Lengaiash
Type
Research Article
Information
Mineralogical Magazine , Volume 56 , Issue 382 , March 1992 , pp. 1 - 16
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2014

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

Agrell, S. O. (1965) Polythermal metamorphism of limestone at Kilchoan, Ardnamurchan. Mineral. Mag., 34, 1–15.Google Scholar
Agrell, S. O. and Gay, P. (1961) Kilchoanite, a polymorph of rankinite. Nature, 189, 743.10.1038/189743a0CrossRefGoogle Scholar
Andersen, T., Griffin, W. L., and O'Reilly, S. Y. (1987) Primary sulphide melt inclusions in mantle-derived megacrysts and pyroxenites. Lithos, 20, 279–94.10.1016/S0024-4937(87)80002-6CrossRefGoogle Scholar
Bishop, F. C., Smith, J. V., and Dawson, J. B. (1978) Na, K, P and Ti in garnet, pyroxene and olivine from peridotite and eclogite xenoliths from African kim- berlites. Ibid. 11, 15573.Google Scholar
Clark, J. R. and Brown, G. E., Jr. (1980) Crystal structure of rasvumite, KFe-S3. Am. Mineral 65, 477–82.Google Scholar
Czamanskc, G. K., Erd, R. C., Sokolova, M. N., Dobrovol'skaya, M. G. and Dmitrieva, M. T. (1979) New data on rasvumite and djerfisherite. Ibid. 64, 776-8.Google Scholar
Czamanskc, G. K., Erd, R. C., Sokolova, M. N., Dobrovol'skaya, M. G. and Dmitrieva, M. T. Leonard, B. F. and Clark, J. R. (1981) Bartonite, a new potassium iron sulfide mineral. Ibid. 66, 369-75.Google Scholar
Dawson, J. B. (1962a) Sodium carbonate lavas from Oldoinyo Lengai, Tanganyika. Nature 195, 1075–6.CrossRefGoogle Scholar
Dawson, J. B. (1962b) The geology of Oldoinyo Lengai. Bull. Volcanol. 24, 349–87.CrossRefGoogle Scholar
Dawson, J. B. (1989) Sodium carbonatite extrusions from Oldoinyo Lcngai, Tanzania: implications for car- bonatite complex genesis. In Carbonatites: genesis and evolution. (Bell, K., ed.). Unwin Hymam London, 255-77.Google Scholar
Dawson, J. B. Bowden, P. and Clark, G. C. (1968) Activity of the carbonatite volcano Oldoinyo Lcngai, 1966. Geol. Rundsch. 57, 865–79.CrossRefGoogle Scholar
Dawson, J. B. Smith, J. V., and Steele, I. M. (1989) Combeite (Na2.33Ca1.74 others0.12)Si3Ov from Oldoinyo Lengai, Tanzania. J. Geol. 97, 365–72.CrossRefGoogle Scholar
Dawson, J. B. Pinkerton, H., Norton, G. E., and Pyle, D. M. (1990) Physicochemical properties of alkali carbonate lavas: data from the 1988 eruption of Oldoinyo Lengai, Tanzania. Geology, 18, 260–3.2.3.CO;2>CrossRefGoogle Scholar
Dmitrieva, M. T., and Ilyuskhin, V. V. (1975) Crystal structure of djerfishcrite. Soviet Physics- — Doklady, 20, 469–70.Google Scholar
Donaldson, C. H., Dawson, J. B., Kanaris-Sotiriou, R., Batchelor, R. A., and Walsh, J. N. (1987) The silicate lavas of Oldoinyo Lengai, Tanzania. Neues. Jahrb. Mineral, Abh. 156, 247–79.Google Scholar
Evans, H. T., Jr. and Clark, J. R. (1981) The crystal structure of bartonite, a potassium iron sulfide, and its relationship to pentlandite and djerfisherite. Am. Mineral., 66, 376–84.Google Scholar
Henmi, K., Kusachi, I., and Henmi, C. (1975) Rankinite and kilchoanite from Fuka, the Town of Bitchu, Okayama Prefecture, Japan. J. Mineral. Soc. Japan, 12, 205–14. (Japanese).Google Scholar
Javoy, M., Pineau, F., Staudacher, T., Cheminee, J. L., and Krafft, M. (1989) Mantle volatiles sampled from a continental rift: the 1988 eruption of Oldoinyo Lengai, Tanzania. Terra Abstracts, 1, 324.Google Scholar
Keller, J. and Krafft, M. (1990) Effusive natrocarbon- atite activity of Oldoinyo Lengai, June 1988. Bull. Voh'anol., 52, 629–45.Google Scholar
Khomyakov, A. P. (1982) Natrite, Na2CO3, a new mineral. Zap. Vses. Mineral. Obsh., 111, 220–25. (Russian).Google Scholar
Kjaarsgaard, B. A. and Hamilton, D. A. (1989) The genesis of carbonatites by immiscibility. In Carbonatites: genesis and evolution. (Bell, K., ed.). Unwin Hyman, London, 308–404.Google Scholar
Kusachi, I., Henmi, C., Kawahara, A. and Henmi, K. (1975) The structure of rankinite. Mineral. J., 8, 38. 47. (Japanese).10.2465/minerj.8.38CrossRefGoogle Scholar
Mitsuda, T. and Fukuo, K. (1969) Synthesis of kilchoanite. Ibid. 6, 17-35. (Japanese).10.2465/minerj1953.6.17CrossRefGoogle Scholar
Moir, G. K. and Glasser, F. P. (1974) Phase equilibria in the system Na2SiOs-CaSiO3 . Phys. Chem. Glasses, 15, 6–11.Google Scholar
Peterson, T. D. (1990) Petrology and genesis of natrocarbonatite. Contrib. Mineral. Petrol., 105, 143–55.CrossRefGoogle Scholar
Saalfeld, H. (1975) X-ray investigation of single crystals of [3-Ca2SiO4 (larnitc) at high temperatures. Amer. Mineral., 60, 824–7.Google Scholar
Sabine, P. A. (1975) Metamorphic processes at high temperature and low pressures, and the petrogenesis of metasomatizcd and assimilated rocks of Carneal, Co. Antrim. Phil. Trans. Roy. Soc. A, 280, 225–67.Google Scholar
Suburi, S., Kusachi, I., Henmi, C., Kawahara, A., Henmi, K., and Kawada, I. (1976) Refinement of the structure of rankinite. Mineral. J. 8, 240–6. (Japanese).CrossRefGoogle Scholar
Sarkar, S. L. and Jeffrey, J. W. (1978) Electron microprobe analysis of Scawt Hill bredigite-larnite rc∼ek. J. Amer. Ceram. Soc., 61, 177–8.10.1111/j.1151-2916.1978.tb09268.xCrossRefGoogle Scholar
Sfimulovich, K. I. (1968) Stability of larnite in the CaO-SIO2-CO2 system. Dokl. Acad. Sci. USSR, Earth Sci. Sect., 177, 142–5.Google Scholar
Smith, D. K., Majumdar, A. J. and Ordway, F. (1961) Re-examination of the polymorphism of dicalcium silicate. J. Amer. Ceram. Soc., 44, 405–11.10.1111/j.1151-2916.1961.tb15472.xCrossRefGoogle Scholar
Smith, J. V., Steele, I. M. and Dawson, J. B. (1988) Carbonate ash from Oldoinyo Lengai, Tanzania: combeite, larnitc, rankinite: K,Na,Fc,Mn,Si,P,CI-sulfide and carbonate differentiates; sodium carbonate; Na,Ca,K-phosphate; reaction textures. Geol. Soc. Amer. Abstr., with Program 20, A103.Google Scholar
Sokolova, M. N., Dobrovol'skaya, M. G., Organova, N. I., Kazakova, M. E., and Dmitrik, A. L. (1970) A sulfide of iron and potassiumthe new mineral, rasvumite. Zap. Vses. Mineralog. Obshch., 99, 712–20.Google Scholar
Taylor, H. F. W. (1971) The crystal structure of kilchoanite Cao(SiO4)(Si3Om), with some comments on related phases. Mineral. Mag., 38, 26–31.CrossRefGoogle Scholar
Virgo, D., Huggins, F. E., and Rosenhauer, M. (1976) Petrologic implications of intrinsic oxygen fugacity measurements on titanium-containing silicate garnets. Carnegie Institution of Washington Yearbook, 75, 730–5.Google Scholar
Zharikov, V. A. and Shmulovich, K. I. (1969) Experimental study on the system CaO-SiO2-CO2 between 800-1000° and at p CO2 = 50-500kg/cm3 . Dok. Acad. Sci. USSR, Earth Sci. Sect., 188, 170–3.Google Scholar