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40Ar/39Ar laser probe evidence concerning the age and associated hazards of the Lake Nyos Maar, Cameroon

Natural Hazards

By:
,
DOI: 10.1007/BF00124394

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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.

Additional Publication Details

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
Number of Pages:
6