40Ar/39Ar laser probe evidence concerning the age and associated hazards of the Lake Nyos Maar, Cameroon
Natural Hazards
By: G. B. Dalrymple and J. P. Lockwood
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Abstract
The waters of Lake Nyos are impounded by a fragile natural dam composed of pyroclastic rocks ejected during the formation of the lake crater (maar). Lateral erosion of this dam has reduced its width from over 500 m to only 45 m. Published whole-rock K-Ar ages of about 100 ka on juvenile basalt from the dam suggests that erosion has been slow and that the dam poses no imminent threat. New apparent 40Ar/39Ar ages of 1.4 to 232 Ma on xenocrystic K-feldspar contained in the basalt show that the xenocrysts, whose source is the 528-Ma crystalline basement, are carriers of inherited radiogenic 40Ar and would cause the whole-rock K-Ar ages to be too old. The best estimate for the age of the maar is provided by a 14C age of 400 ?? 100 yr BP on charcoal from the base of the dam. This young age indicates that the dam is eroding at a relatively rapid rate; its failure, perhaps within a few decades, would result in a major flood and imperil thousands of people living downstream in Cameroon and eastern Nigeria. ?? 1990 Kluwer Academic Publishers.
Suggested Citation
Dalrymple, G.B., and Lockwood, J.P., 1990, 40Ar/39Ar laser probe evidence concerning the age and associated hazards of the Lake Nyos Maar, Cameroon: Natural Hazards, v. 3, no. 4, p. 373-378, https://doi.org/10.1007/BF00124394.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | 40Ar/39Ar laser probe evidence concerning the age and associated hazards of the Lake Nyos Maar, Cameroon |
| Series title | Natural Hazards |
| DOI | 10.1007/BF00124394 |
| Volume | 3 |
| Issue | 4 |
| Year Published | 1990 |
| Language | English |
| Publisher location | Kluwer Academic Publishers |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Natural Hazards |
| First page | 373 |
| Last page | 378 |