Origin and age of the Lake Nyos maar, Cameroon

Abstract Lake Nyos occupies a young maar crater in the Precambrian granitic terrane of northwest Cameroon. The lake is partly surrounded by poorly consolidated, ultramafic nodule-bearing pyroclastic surge deposits that were explosively ejected from the Nyos crater at the time of its formation. Radiocarbon dates show that the maar probably formed about 400 years ago. Field evidence suggests that carbon dioxide could have been the principal volatile involved in the formation of the Nyos maar, and that the role of water may have been minor. The formation of the Nyos maar was preceded by a brief period of effusive basaltic volcanism, but the maar itself may have largely formed by cold, ‘dry’ explosive processes. Carbon dioxide may still be trapped interstitially in a diatreme inferred to underlie Lake Nyos; its gradual release into the waters of Lake Nyos may have set the stage for the tragic gas-release event of August 21, 1986. Only young maar lakes such as Nyos may pose a danger of future lethal gas releases.

[1]  B. C. Hearn.  Diatremes with Kimberlitic Affinities in North-Central Montana , 1968, Science.

[2]  George W. Kling,et al.  Comparative transparency, depth of mixing, and stability of stratification in lakes of Cameroon, West Africa1 , 1988 .

[3]  I. Barnes,et al.  Possible role of mantle-derived CO2 in causing two “phreatic” explosions in Alaska , 1979 .

[4]  V. Lorenz.  Vesiculated tuffs and associated features , 1974 .

[5]  V. Lorenz.  Explosive Volcanism of the West Eifel Volcanic Field/Germany , 1984 .

[6]  Stephen Self,et al.  Ukinrek Maars, Alaska, I. April 1977 eruption sequence, petrology and tectonic setting , 1980 .

[7]  William I. Rose,et al.  An estimate of gas emissions and magmatic gas content from Kilauea volcano , 1985 .

[8]  J. Lockwood,et al.  The potential for catastrophic dam failure at Lake Nyos maar, Cameroon , 1988 .

[9]  V. Lorenz.  On the growth of maars and diatremes and its relevance to the formation of tuff rings , 1986 .

[10]  A. Maréchal.  Géologie et géochimie des sources thermominérales du Cameroun , 1976 .

[11]  H. Tazieff.  Mechanisms of the Nyos carbon dioxide disaster and of so-called phreatic steam eruptions , 1989 .

[12]  B. Houghton,et al.  Mixed deposits of simultaneous strombolian and phreatomagmatic volcanism: Rothenberg volcano, east Eifel volcanic field , 1986 .

[13]  H. R. Compton,et al.  The 1986 Lake Nyos Gas Disaster in Cameroon, West Africa , 1987, Science.

[14]  J. Lockwood,et al.  Recovery of datable charcoal beneath young lavas: Lessons from Hawaii , 1980 .

[15]  J. Fitton,et al.  The Cameroon line, West Africa, and its bearing on the origin of oceanic and continental alkali basalt , 1985 .

[16]  Allan R. Chivas,et al.  Liquid carbon dioxide of magmatic origin and its role in volcanic eruptions , 1987, Nature.

[17]  I. Barnes,et al.  Volatiles of Mount St. Helens and their origins , 1984 .

[18]  S. J. Freeth.  The Lake Nyos gas disaster , 1987 .

[19]  S. J. Freeth.  Lake Nyos Dam , 1988 .

[20]  V. Lorenz,et al.  On the formation of maars , 1973 .