Advertisement

Bulletin of Volcanology

, Volume 56, Issue 1, pp 47–61 | Cite as

Volcanological and petrological evolution of Nyiragongo volcano, Virunga volcanic field, Zaire

  • Alain Demant
  • Patrick Lestrade
  • Ruananza T Lubala
  • Ali B Kampunzu
  • Jacques Durieux
Article

Abstract

Three major phases are distinguished during the growth of Nyiragongo, an active volcano at the western limit of the Virunga Range, Zaire. Lavas erupted during phase 1 are strongly undersaturated melilities characterized by the presence of kalsilite phenocrysts, perovskite, and the abundance of calcite in the matrix. Such lavas crop out mainly on the inner crater wall and progressively evolve toward more aphyric melilite nephelinites well represented on the flanks of the volcano. Adventive vents lying at the base of the cone developed along radial fracture systems and erupted olivine and/or clinopyroxene-rich melilitites or nephelinites. Stage 2 lavas are melilite-free nephelinites. Clinopyroxene is the main phenocryst and feldspathoids are abundant in the lavas exposed on the crater wall. These flows result from periodic overflowing of a magma column from an open crater. Extensive fissure flows which erupted from the base of the cone at the end of this stage are related to widespread draining out of magma which in turn induces the formation of the summit pit crater. Magmas erupted during stage 3 are relatively aphyric melilite nephelinites and the main volcanological characteristic is the permanent lava lake observed into the pit crater until the 1977 eruption. Fluctuations of the level of the lava lake was responsible for the development of the inner terraces. Periodic overflowing of the lava lake from the central pit formed the nepheline aggregate lava flows. Petrography and major element geochemistry allow the determination of the principal petrogenetic processes. Melilitites and nephelinites erupted from the summit crater are lavas derived, via clinopyroxene fractionation, from a more primitive melt. The abundance of feldspathoids in these lavas is in keeping with nepheline flotation. Aphyric melilite nephelinites covering the flanks and the extensive fissure flows have a homogencous chemical composition; rocks from the historical lava lake are slightly more evolved. All these lavas differentiated in a shallow reservoir. Lavas erupted from the parasitic vents are mainly olivine and/or clinopyroxene-phyric rocks. Rushayite and picrites from Muja cone are peculiar high-magnesium lavas resulting from the addition of olivine xenocrysts to melilitic or nephelinitic melts. Fluid and melt inclusions in olivine and clinopyroxene phenocrysts indicate a crystallization depth of 10–14 km. A model involving two reservoirs located at different depths and periodically connected is proposed to explain the petrography of the lavas; this hypothesis is in accordance with geophysical data.

Key words

Nyiragongo volcanology petrology melilitite nephelinite feldspathoid flotation 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Albarède F (1992) How deep do common basaltic magmas form and differentiate. J Geophys Res 97:10997–11009Google Scholar
  2. Albarède F, Tamagnan V (1988) Modelling the recent geochemical evolution of the Piton de la Fournaise volcano, Réunion Island, 1931–1986. J Petrol 29:997–1030Google Scholar
  3. Aoki KI, Yoshida T, Yusa K, Nakamura Y (1985) Petrology and geochemistry of the Nyamuragira volcano, Zaire. J Volcanol Geotherm Res 25:1–28CrossRefGoogle Scholar
  4. Bagdasaryan GP, Gerasimovski VI, Polyakov AI, Gukasyan RK (1973) Age of volcanic rocks in the rift zones of East Africa. Geokhimiya 1:84–90Google Scholar
  5. Demant A, Lestrade P, Lubala T, Kampunzu A (1993) Volcanological and petrological evolution of Nyiragongo volcano, Virunga volcanic field, Zaire. Terra Abstracts 5:570Google Scholar
  6. De Mulder M, Pasteels P (1986) K−Ar geochronology of the Karisimbi volcano (Virunga, Rwanda-Zaire). J Afric Earth Sci 5:575–579Google Scholar
  7. De Mulder M, Hertogen J, Deutsch S, Andre L (1986) The role of crustal contamination in the potassic suite of the Karisimbi volcano (Virunga, African rift valley). Chem Geol 57:117–136Google Scholar
  8. Denaeyer ME (1954) Les anciens volcans sous-lacustres de la bordure nord du lac Kivu. Bull Soc Belge Géol Paléont Hydro 63:280–298Google Scholar
  9. Denaever ME (1960) Composition de la lave actuelle du Nyiragongo et de quelques laves similaires de ce volcan. Bull Acad R Sc Outre-Mer (Bruxelles) 6:999–1013Google Scholar
  10. Denaeyer ME (1963) Les hyaloclastites de la rive nord du lac Kivu (Congo). Bull Volcanol 25:201–215Google Scholar
  11. Denaeyer ME (1965) Recueil d'analyses des laves du fossé tectonique de l'Afrique Centrale (Kivu, Rwanda, Toro-Ankole). Mus R Afr Centr-Tervuren Belg, Ann série in-8° Sci Géol 49:234 ppGoogle Scholar
  12. Denaeyer ME (1966) La rushayite, homologue sodique de la katungite, lave nouvelle du volcan Nyiragongo (Kivu, Afrique Centrale). Bull Soc Franç Miné Cristallogr 89:107–119Google Scholar
  13. Denaeyer ME (1972) Les laves du fossé tectonique de l'Afrique Centrale (Kivu, Rwanda, Toro-Ankole). I. Supplément au recueil d'analyses de 1965. II. Magmatologie. Mus R Afr Centr-Tervuren Belg, Ann série in-8° Sci Géol 72:134 ppGoogle Scholar
  14. Hertogen J, Vanlerberghe L, Namegabe MR (1985) Geochemical evolution of the Nyiragongo volcano (Virunga, Western African Rift, Zaire). Bull Geol Soc Finland 57:21–35Google Scholar
  15. Krafft M, Krafft K (1983) La réapparition du lac de lave dans le cratère du volcan Nyiragongo de juin à septembre 1982 (Kivu-Zaïre). Histoire, dynamisme, débits et risques volcaniques. CR Acad Sci Paris 296:797–802Google Scholar
  16. Louaradi D, Pineau F, Javoy M, Demant A (1992) Origin of carbonates in the Nyiragongo magma: evidence from carbon and oxygen isotopes. EOS 73:352Google Scholar
  17. Louaradi D, Clochiatti R, Pineau F, Javoy M (1993) Magma storage beneath Nyiragongo volcano (Zaire): evidence from fluid and melt inclusions. Terra Abstracts 5:573Google Scholar
  18. Marcelot G, Rançon JP, Demange J (1985) The potassic series of Karisimbi volcano (Virunga Range, Rwanda): volcanological and petrological aspects. J Volcanol Geotherm Res 26:99–129CrossRefGoogle Scholar
  19. Martin B (1987) Etude détaillée de la solidification d'un filon de basalte alcalin du Lodévois. Thèse Univ P et M Curie 87-24:105 ppGoogle Scholar
  20. Peck DL, Wright TL, Decker RW (1982) The lava lakes of Kilauea. In: Decker RW, Decker B (eds) Scientific American, ‘Volcanoes and the Earth's interior’. Freeman, San Francisco 48–56Google Scholar
  21. Pottier Y (1978) Première éruption historique du Nyiragonog et manifestations advantives simultanées du volcan Nyamuragira (chaîne des Virunga-Kivu-Zaïre: Déc 76-Juin 77). Mus R Afr Centr-Tervuren Belg, Dépt Géol Min Rapp ann: 157–175Google Scholar
  22. Pouclet A (1973) Contribution à la connaissance du volcan Nyiragongo (Rift ouest-africain). Les éruptions intra-cratérales de juillet 1971 à avril 1972. Bull Volcanol 37:37–72Google Scholar
  23. Sahama TG (1957) Complex kalsilite-nepheline phenocrysts in Kabfumu lava, Nyiragongo area, north Kivu in Belgian Congo. J Geol 65:515–526Google Scholar
  24. Sahama TG (1960) Kalsilite in the lavas of Mt Nyiragongo (Belgian Congo). J Petrol 1:146–171Google Scholar
  25. Sahama TG (1962) Petrology of Mt Nyiragongo. Trans Edinburgh Geol Soc 19:1–29Google Scholar
  26. Sahama TG (1968) Mineralogical composition of the Nyiragongo rocks. Geol Rund 57:564–573Google Scholar
  27. Sahama TG (1973) Evolution of the Nyiragongo magma. J Petrol 14:33–48Google Scholar
  28. Sahama TG (1978) The Nyiragongo main cone. Mus R Afr Centr-Tervuren Belg, Ann série in-8° Sci Géol 81:88 ppGoogle Scholar
  29. Sahama TG, Meyer A (1958) Study of the volcano Nyiragongo, a progress report. Inst Parcs nationaux Congo Belge, Missions d'études vulcanologiques 2:85 ppGoogle Scholar
  30. Tanaka K (1983) Seismicity and focal mechanism of the volcanic earthquakes in the Virunga volcanic region. In: Hamagushi H (ed) Volcanoes Nyiragongo and Nyamuragira: geophysical aspects. Univ. Tôhoku, Japan:19–28Google Scholar
  31. Tazieff H (1949) Première exploration du cratère du volcan Nyiragongo. Bull Soc Belge Géol 58:165–172Google Scholar
  32. Tazieff H (1966) Etat actuel des connaissances sur le volcan Nyiragongo (République démocratique du Congo). Bull Soc Géol France, (7) VIII:176–200Google Scholar
  33. Tazieff H (1977) An exceptional eruption: Mt Nyiragongo, Jan. 10th, 1977. Bull Volcanol 40:189–200Google Scholar
  34. Tazieff H (1984) Mt. Nyiragongo: renewed activity of the lava lake. J Volcanol Geotherm Res 20:267–280CrossRefGoogle Scholar
  35. Tazieff H (1985) Recent activity at Nyiragongo and lava lake occurences. Bull Geol Soc Finland 57:11–19Google Scholar
  36. Thompson RN (1975) The 1-atm liquidus oxygen fugacities of some tholeiitic intermediate, alkalic and ultra-alkalic lavas. Am J Sci 275:1049–1072Google Scholar
  37. Thonnard RL, Denaever ME (1965) Carte volcanologique des Virunga, feuille no1, groupe occidental. Centre National de Volcanologie (Belgique), publication no32Google Scholar
  38. Thorpe RS, Smith K (1974) Distribution of Cenozoic volcanism in Afrika. Earth Planet Sci Lett 21:91–95Google Scholar
  39. Vanlerberghe L, Hertogen J, MacDougall JD (1987) Geochemical evolution and Th-U isotope systematics of alkaline lavas from Nyiragongo volcano (African Rift). Terra Cognita Abstracts 7:367Google Scholar
  40. Velde D, Yoder HS Jr (1976) The chemical composition of melilite-bearing eruptive rocks. Carnegie Institution, Washington, Yearbook 75:574–580Google Scholar
  41. Vollmer R, Norry MJ (1983a) Unusual isotopic variations in Nyiragongo nephelinites. Nature 301:141–143CrossRefGoogle Scholar
  42. Vollmer R, Norry MJ (1983b) Possible origin of K-rich volcanic rocks from Virunga, East Africa, by metasomatism of continental crustal material: Pb, Nd and Sr isotopic evidence. Earth Planet Sci Lett 64:374–386CrossRefGoogle Scholar
  43. Vollmer R, Nixon PH, Condliffe E (1985) Petrology and geochemistry of a U and Th-enriched nephelinite from Mt Nyiragongo, Zaire: its bearing on ancient mantle metasomatism. Bull Geol Soc Finland 57:37–46Google Scholar
  44. Wood CA (1980) Morphometric evolution of cinder cones. J Volcanol Geotherm Res 7:387–413CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 1994

Authors and Affiliations

  • Alain Demant
    • 1
    • 2
  • Patrick Lestrade
    • 1
    • 2
  • Ruananza T Lubala
    • 3
  • Ali B Kampunzu
    • 3
  • Jacques Durieux
    • 4
  1. 1.Laboratoire de Pétrologie Magmatique URA 1277 CNRSUniversité Aix-Marseille IIIMarseille Cedex 13France
  2. 2.Centre de Recherches VolcanologiquesClermont-FerrandFrance
  3. 3.Laboratoire de PétrologieUniversité de LubumbashiLubumbashiZaïre
  4. 4.LyonFrance

Personalised recommendations