Advertisement

Bulletin of Volcanology

, Volume 72, Issue 8, pp 893–912 | Cite as

Fundamental changes in the activity of the natrocarbonatite volcano Oldoinyo Lengai, Tanzania

I. New magma composition during the 2007–2008 explosive eruptions
  • Jörg KellerEmail author
  • Jurgis Klaudius
  • Matthieu Kervyn
  • Gerald G. J. Ernst
  • Hannes B. Mattsson
Research Article

Abstract

With a paroxysmal ash eruption on 4 September 2007 and the highly explosive activity continuing in 2008, Oldoinyo Lengai (OL) has dramatically changed its behavior, crater morphology, and magma composition after 25 years of quiet extrusion of fluid natrocarbonatite lava. This explosive activity resembles the explosive phases of 1917, 1940–1941, and 1966–1967, which were characterized by mixed ashes with dominantly nephelinitic and natrocarbonatitic components. Ash and lapilli from the 2007–2008 explosive phase were collected on the slopes of OL as well as on the active cinder cone, which now occupies the entire north crater having buried completely all earlier natrocarbonatite features. The lapilli and ash samples comprise nepheline, wollastonite, combeite, Na-åkermanite, Ti-andradite, resorbed pyroxene and Fe–Ti oxides, and a Na–Ca carbonate phase with high but varying phosphorus contents which is similar, but not identical, to the common gregoryite phenocrysts in natrocarbonatite. Lapilli from the active cone best characterize the erupted material as carbonated combeite–wollastonite–melilite nephelinite. The juvenile components represent a fundamentally new magma composition for OL, containing 25–30 wt.% SiO2, with 7–11 wt.% CO2, high alkalies (Na2O 15–19%, K2O 4–5%), and trace-element signatures reminiscent of natrocarbonatite enrichments. These data define an intermediate composition between natrocarbonatite and nephelinite, with about one third natrocarbonatite and two thirds nephelinite component. The data are consistent with a model in which the carbonated silicate magma has evolved from the common combeite–wollastonite nephelinite (CWN) of OL by enrichment of CO2 and alkalies and is close to the liquid immiscible separation of natrocarbonatite from carbonated nephelinite. Material ejected in April/May 2008 indicates reversion to a more common CWN composition.

Keywords

Oldoinyo Lengai Explosive eruptions 2007–2008 paroxysms New silicate magma composition Carbonated nephelinite 

Notes

Acknowledgments

Access to the summit of Oldoinyo Lengai had become difficult since the paroxysm of 4 September 2007. Tim Leach from Ngare Sero Lodge explored and opened, together with local Maasai, a new route from the east–southeast. The expedition of 7 December 2007 used this route with the help of the Maasai guides Saringe, Tumba, and Lekoko from Engare Sero. This logistic support is gratefully acknowledged. We thank Benoît Wihelmi, Tim Leach, and Tom Pfeiffer for providing and granting permission to use some of their spectacular pictures. Julie Albaric, Evelyne Pradal, and Chris Weber contributed the additional samples of November 2007 and February 2008 ashes and lava bombs of April 2008, respectively. We also thank all who contributed with observations and photographs, which enabled to follow the activity evolution from distance. This includes in particular Thomas Holden, Jens Fissenebert, and Chris Weber. We acknowledge stimulating discussions with Barry Dawson, Roger Mitchell, and Bruce Kjarsgaard. Research of JKe and JKl at OL is supported by DFG project Ke 136/40. MK and GGJE are supported by postdoctoral grants of the Fonds voor Wetenschappelijk Onderzoek-Vlaanderen. Melanie Schrage, Sigrid Hirth-Walther, Isolde Schmidt, and Dagmar Flemming of MGI Freiburg were of invaluable help in sample and thin section preparation and chemical analyses. Hiltrud Müller-Sigmund gave expert advice at the electron microprobe. Jörg Erzinger of GFZ Potsdam is thanked for his spontaneous availability when asked for additional fluorine and chlorine determinations. The paper greatly benefited from the careful, competent, and constructive reviews by Barry Dawson and Bruce Kjarsgaard.

References

  1. Barns TA (1921) The highlands of the Great Craters, Tanganyika Territory. Geogr J 58:401–416CrossRefGoogle Scholar
  2. Bell K, Dawson JB (1995) Nd and Sr isotope systematics of the active carbonatite volcano, Oldoinyo Lengai. In: Bell K, Keller J (eds) Carbonatite volcanism: Oldoinyo Lengai and the petrogenesis of natrocarbonatites. IAVCEI Proc Volcanol 4. Springer, Berlin, pp 113–123Google Scholar
  3. Bell K, Keller J (eds) (1995) Carbonatite volcanism: Oldoinyo Lengai and the petrogenesis of natrocarbonatites. IAVCEI Proceedings in Volcanology 4. Springer, Berlin, 210 ppGoogle Scholar
  4. Bell K, Simonetti A (1996) Carbonatite magmatism and plume activity: implication from the Nd, Pb and Sr isotope systematics of Oldoinyo Lengai. J Petrol 37:1321–1339CrossRefGoogle Scholar
  5. Belton F (2007, 2008, 2009) Oldoinyo Lengai: the mountain of God. http://www.mtsu.edu/∼fbelton/lengai.html
  6. Church AA, Jones AP (1995) Silicate–carbonate immiscibility at Oldoinyo Lengai. J Petrol 36:869–889Google Scholar
  7. Dawson JB (1962) The geology of Oldoinyo Lengai. Bull Volcanol 24:348–387CrossRefGoogle Scholar
  8. Dawson JB (1998) Peralkaline nephelinite–natrocarbonatite relationships at Oldoinyo Lengai, Tanzania. J Petrol 39:2077–2094CrossRefGoogle Scholar
  9. Dawson JB (2008) The Gregory Rift Valley and Neogene—recent volcanoes of Northern Tanzania. Geol Soc London Mem 33:1–102CrossRefGoogle Scholar
  10. Dawson JB, Bowden P, Clark GC (1968) Activity of the carbonatite volcano Oldoinyo Lengai, 1966. Geol Rundsch 57:865–879CrossRefGoogle Scholar
  11. Dawson JB, Smith JV, Jones AP (1985) A comparative study of bulk rock and mineral chemistry of olivine melilitites and associated rocks from East and South Africa. Neues Jahrbuch für Mineralogie, Abhandlungen 152:143–175Google Scholar
  12. Dawson JB, Garson MS, Roberts B (1987) Altered former alkalic carbonatite lava from Oldoinyo Lengai, Tanzania: inferences for calcite carbonatite lavas. Geology 15:765–768CrossRefGoogle Scholar
  13. Dawson JB, Smith JV, Steele IM (1989) Combeite (Na2.33Ca1.74others0.12)Si3O9 from Oldoinyo Lengai, Tanzania. J Geol 97:365–372CrossRefGoogle Scholar
  14. Dawson JB, Pinkerton H, Norton GE, Pyle D (1990) Physicochemical properties of alkali carbonatite lavas: data from the 1988 eruption of Oldoinyo Lengai, Tanzania. Geology 18:260–263CrossRefGoogle Scholar
  15. Dawson JB, Smith JV, Steele IM (1992) 1966 ash eruption of the carbonatite volcano Oldoinyo Lengai: mineralogy of lapilli and mixing of silicate and carbonate magmas. Mineral Mag 56:1–16CrossRefGoogle Scholar
  16. Dawson JB, Pinkerton H, Pyle DM, Nyamweru C (1994) June 1993 eruption of Oldoinyo Lengai, Tanzania; exceptionally viscous and large carbonatite lava flows and evidence for coexisting silicate and carbonate magmas. Geology 22:799–802CrossRefGoogle Scholar
  17. Dawson JB, Keller J, Nyamweru C (1995) Historic and recent eruptive activity of Oldoinyo Lengai. In: Bell K, Keller J (eds) Carbonatite volcanism: Oldoinyo Lengai and the petrogenesis of natrocarbonatites. IAVCEI Proc Volcanol 4. Springer, Berlin, pp 4–22Google Scholar
  18. Donaldson CH, Dawson JB, Kanaris-Sotiriou R, Batchelor RA, Walsh JN (1987) The silicate lavas of Oldoinyo Lengai, Tanzania. Neues Jahrbuch für Mineralogie, Abhandlungen 156:247–279Google Scholar
  19. Fischer GA (1885) Bericht über die im Auftrage der Geographischen Gesellschaft in Hamburg unternommene Reise in das Masai-Land 1882–1883. II: Begleitworte zur Original-Routenkarte. Mitt Geogr Ges Hamburg 1885:189–237Google Scholar
  20. Freestone IC, Hamilton DL (1980) The role of liquid immiscibility in the genesis of carbonatites—an experimental study. Contrib Mineral Petrol 73:105–117CrossRefGoogle Scholar
  21. Global Volcanism Network Bulletin (2007) Oldoinyo Lengai (Tanzania). GVN 32, no. 11, 10–16Google Scholar
  22. Global Volcanism Network Bulletin (2008) Oldoinyo Lengai (Tanzania), GVN 33, no. 2, 2–6 (J Keller et al.), GVN 33, no. 8, 12–14Google Scholar
  23. Global Volcanism Network Bulletin (2009) Oldoinyo Lengai (Tanzania), GVN 34, no. 8, 9–12Google Scholar
  24. Guest NJ (1956) The volcanic activity of Oldoinyo L'Engai, 1954. Rec Geol Surv Tanganyika 4:56–59Google Scholar
  25. Hamilton DL, Bedson P, Esson J (1989) The behaviour of trace elements in the evolution of carbonatites. In: Bell K (ed) Carbonatites—genesis and evolution. Unwin Hyman, London, pp 405–427Google Scholar
  26. Hay RL (1983) Natrocarbonatite tephra of Kerimasi volcano, Tanzania. Geology 11:599–602CrossRefGoogle Scholar
  27. Hobley CW (1918) A volcanic eruption in East Africa. J East Africa Uganda Nat Hist Soc 13:339–343Google Scholar
  28. Keller J, Krafft M (1990) Effusive natrocarbonatite activity of Oldoinyo Lengai, June 1988. Bull Volcanol 52:629–645CrossRefGoogle Scholar
  29. Keller J, Spettel B (1995) Trace element composition and petrogenesis of natrocarbonatites. In: Bell K, Keller J (eds) Carbonatite volcanism: Oldoinyo Lengai and the petrogenesis of natrocarbonatites. IAVCEI Proc Volcanol 4. Springer, Berlin, pp 70–86Google Scholar
  30. Keller J, Zaitsev AN (2006) Calciocarbonatitic dykes at Oldoinyo Lengai, Tanzania: the fate of natrocarbonatite. Can Mineral 44:857–876CrossRefGoogle Scholar
  31. Keller J, Zaitsev AN, Wiedenmann D (2006) Primary magmas at Oldoinyo Lengai: the role of olivine melilitites. Lithos 91:150–172CrossRefGoogle Scholar
  32. Keller J, Zaitsev AN, Klaudius J (2007) Geochemistry and petrogenetic significance of natrocarbonatites at Oldoinyo Lengai, Tanzania: composition of lavas from 1988 to 2007. Goldschmidt Conference 2007, Cologne, AbstractsGoogle Scholar
  33. Kervyn M, Klaudius J, Keller J, Kervyn F, Mattsson H, Belton F, Mbede E, Jacobs P, Ernst GGJ (2008a) Voluminous lava floods at Oldoinyo Lengai in 2006: chronology of events and insights into the shallow magmatic system. Bull Volcanol 70:1069–1086CrossRefGoogle Scholar
  34. Kervyn M, Klaudius J, Keller J, Mbede E, Jacobs P, Ernst GGJ (2008b) Remote sensing study of sector collapses and debris-avalanche deposits at Oldoinyo Lengai and Kerimasi volcanoes, Tanzania. Int J Rem Sens 29:6565–6595CrossRefGoogle Scholar
  35. Kervyn M, Ernst GGJ, Keller J, Vaughan G, Klaudius J, Pradal E, Belton F, Mattsson H, Mbede E, Jacobs P (2010) Fundamental changes in the activity of the natrocarbonatite volcano Oldoinyo Lengai, Tanzania. II. Eruptive behaviour. Bull Volcanol. doi: 10.1007/s00445-010-0360-0
  36. Kjarsgaard BA (1998) Phase relations of a carbonated high CaO-nephelinite at 0.2 and 0.5 GPa. J Petrol 39:2061–2077CrossRefGoogle Scholar
  37. Kjarsgaard BA, Hamilton DL (1989) The genesis of carbonatites by immiscibility. In Bell K (ed) Carbonatites—genesis and evolution. Unwin Hyman, London, pp 388–404Google Scholar
  38. Kjarsgaard BA, Hamilton DL, Peterson TD (1995) Peralkaline nephelinite/carbonatite liquid immiscibility: comparison of phase composition in experiments and natural lavas from Oldoinyo Lengai. In: Bell K, Keller J (eds) Carbonatite volcanism: Oldoinyo Lengai and the petrogenesis of natrocarbonatites. IAVCEI Proc Volcanol 4. Springer, Berlin, pp 163–190Google Scholar
  39. Klaudius J, Keller J (2004) Quaternary debris avalanche deposits at Oldoinyo Lengai (Tanzania). IAVCEI General Assembly, Pucón, Chile 2004, AbstractsGoogle Scholar
  40. Klaudius J, Keller J (2006) Peralkaline silicate lavas at Oldoinyo Lengai, Tanzania. Lithos 91:173–190CrossRefGoogle Scholar
  41. Koster van Groos AF, Wyllie PJ (1968) Liquid immiscibility in the join NaAlSi3O8-Na2CO3-H2O and its bearing on the genesis of carbonatites. Am J Sci 266:932–967CrossRefGoogle Scholar
  42. Macdonald R, Kjarsgaard BA, Skilling IP, Davies GR, Hamilton DL, Black DS (1993) Liquid immiscibility between trachyte and carbonate in ash flow tuffs from Kenya. Contrib Mineral Petrol 114:276–287CrossRefGoogle Scholar
  43. Mattsson HB, Reusser E (2010) Mineralogical and geochemical characterization of ashes from an early phase of the explosive September 2007 eruption of Oldoinyo Lengai (Tanzania). J Afr Earth Sci (in press)Google Scholar
  44. McDonough WF, Sun SS (1995) The composition of the Earth. Chem Geol 120:223–253CrossRefGoogle Scholar
  45. Mitchell RH (2006) Sylvite and fluorite microcrysts, and fluorite-nyerereite intergrowths from natrocarbonatite, Oldoinyo Lengai, Tanzania. Mineral Mag 70:103–114CrossRefGoogle Scholar
  46. Mitchell RH (2009) Peralkaline nephelinite–natrocarbonatite immiscibility and carbonatite assimilation at Oldoinyo Lengai, Tanzania. Contrib Mineral Petrol 158:589–598. doi: 10.1007/s00410-009-0398-1 CrossRefGoogle Scholar
  47. Mitchell R, Dawson B (2007) The September 24th, 2007 ash eruption of the carbonatite volcano, Oldoinyo Lengai, Tanzania: mineralogy of the ash and implications for the formation of new hybrid magma type. Mineral Mag 71:483–492CrossRefGoogle Scholar
  48. Neumann O (1894) In: Matschie P, Nachrichten aus den deutschen Schutzgebieten. Deutsch-Ostafrika. Von der wissenschaftlichen Expedition Oskar Neumanns. Deutsches Kolonialblatt 21, pp 421–424Google Scholar
  49. Nyamweru C (1990) Observations on changes in the active crater of Oldoinyo Lengai from 1960 to1988. J Afr Earth Sci 11:385–390CrossRefGoogle Scholar
  50. Nyamweru C (1997) Changes in the crater of Oldoinyo Lengai. J Afr Earth Sci 25:43–53CrossRefGoogle Scholar
  51. Peterson TD (1989a) Peralkaline nephelinites. I. Comparative petrology of Shombole and Oldoinyo L`engai, East Africa. Contrib Mineral Petrol 101:458–478CrossRefGoogle Scholar
  52. Peterson TD (1989b) Peralkaline nephelinites. II. Low pressure fractionation and the hypersodic lavas of Oldoinyo Lengai. Contrib Mineral Petrol 102:336–346CrossRefGoogle Scholar
  53. Peterson TD (1990) Petrology and genesis of natrocarbonatite. Contrib Mineral Petrol 105:143–155CrossRefGoogle Scholar
  54. Peterson TD, Kjarsgaard BA (1995) What are the parental magmas at Oldoinyo Lengai? In: Bell K, Keller J (eds) Carbonatite volcanism: Oldoinyo Lengai and the petrogenesis of natrocarbonatites IAVCEI Proc Volcanol 4. Springer, Berlin, pp 148–162Google Scholar
  55. Petibon CM, Kjarsgaard BA, Jenner GA, Jackson SE (1998) Phase relationships of a silicate bearing natrocarbonatite from Oldoinyo Lengai at 20 and 100 MPa. J Petrol 39:2137–2153CrossRefGoogle Scholar
  56. Pyle DM, Dawson JB, Ivanovich M (1991) Short-lived decay series disequilibria in the natrocarbonatite lavas of Oldoinyo Lengai, Tanzania: constraints on the timing of magma genesis. Earth Planet Sci Lett 105:378–396CrossRefGoogle Scholar
  57. Reck H (1914) Oldoinyo L’Engai, ein tätiger Vulkan im Gebiete der Deutsch-Ostafrikanischen Bruchstufe. Branca-Festschrift, Berlin, pp 373–409Google Scholar
  58. Reck H, Schulze G (1921) Ein Beitrag zur Kenntnis des Baues und der jüngsten Veränderung des L´Engai Vulkans im nördlichen Deutsch-Ostafrika. Z Vulk 6:47–71Google Scholar
  59. Richard JJ (1942) Volcanological observations in East Africa. I Oldoinyo Lengai. The 1940–1 eruption. J East Africa Uganda Nat Hist Soc 16:89–108Google Scholar
  60. Simonetti A, Bell K, Shrady C (1997) Trace and rare-earth-element geochemistry of the June 1993 natrocarbonatite lavas, Oldoinyo Lengai (Tanzania). Implications for the origin of carbonatite magmas. J Volcanol Geotherm Res 75:89–106CrossRefGoogle Scholar
  61. Uhlig C (1905) Bericht über die Expedition der Otto-Winter-Stiftung nach den Umgebungen des Meru. Zeitschrift der Gesellschaft für Erdkunde zu Berlin, Jg 1905, 120–123Google Scholar
  62. Uhlig C, Jaeger F (1942) Die Ostafrikanische Bruchstufe und die angrenzenden Gebiete zwischen den Seen Magad und Lawa ya Mweri sowie dem Westfuss des Meru. Deutsches Inst Länderkde, Wissensch Veröffentlichungen, Neue Serie 10, 284 ppGoogle Scholar
  63. Vaughan G, Kervyn M, Realmuto V, Adams M, Hook S (2008) Satellite measurements of recent volcanic activity at Oldoinyo Lengai, Tanzania. J Volcanol Geotherm Res 173:196–206CrossRefGoogle Scholar
  64. Veksler IV, Petibon C, Jenner GA, Dorfman AM, Dingwell DB (1998) Trace element partitioning in immiscible silicate–carbonate liquid systems: an initial experimental study using a centrifuge autoclave. J Petrol 39:2095–2105CrossRefGoogle Scholar
  65. Wiedenmann D, Zaitsev AN, Britvin SN, Krivovichev SV, Keller J (2009) Alumoåkermanite, (Ca, Na)2(Al, Mg, Fe2+)(Si2O7), a new mineral from the active carbonatite–nephelinite–phonolite volcano Oldoinyo Lengai, northern Tanzania. Mineral Mag 73:373–384CrossRefGoogle Scholar
  66. Williams RW, Gill JB, Bruland KW (1986) Ra-Th disequilibria systematics: timescale of carbonatite magma formation at Oldoinyo Lengai volcano, Tanzania. Geochim Cosmochim Acta 50:1249–1259CrossRefGoogle Scholar
  67. Zaitsev AN, Keller J, Spratt J, Perova EN, Kearsley A (2008a) Nyerereite–pirssonite–calcite–shortite relationships in altered natrocarbonatites, Oldoinyo Lengai, Tanzania. Can Mineral 46:1077–1094CrossRefGoogle Scholar
  68. Zaitsev AN, Keller J, Spratt J, Jeffries TE, Sharigin VV (2008b) Chemical composition of nyerereite and gregoryite in natrocarbonatites of Oldoinyo Lengai Volcano, Tanzania. Proc Russ Mineral Soc 137:101–111Google Scholar

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Jörg Keller
    • 1
    Email author
  • Jurgis Klaudius
    • 1
    • 4
  • Matthieu Kervyn
    • 2
  • Gerald G. J. Ernst
    • 2
  • Hannes B. Mattsson
    • 3
  1. 1.Institut für Geowissenscahften, Mineralogie–GeochemieAlbert-Ludwigs-Universität FreiburgFreiburgGermany
  2. 2.Mercator and Ortelius Research Centre for Eruption Dynamics, Department of Geology and Soil ScienceGhent UniversityGhentBelgium
  3. 3.Institute of Geochemistry and PetrologyETH Zürich, Swiss Federal Institute of TechnologyZurichSwitzerland
  4. 4.Terratec Geophysical ServicesHeitersheimGermany

Personalised recommendations