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The significance of siderite in the sediments from Lake Nyos, Cameroon

par Bernard, Alain ;Symonds, Robert B.
Référence Journal of volcanology and geothermal research, 39, 2-3, page (187-194)
Publication Publié, 1989-11

Article révisé par les pairs

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Résumé :

Small amounts (1-3 wt.%) of endogenic siderite (FeCO3) and traces of pyrite (FeS2) are present in a 1 m-long sediment core from Lake Nyos. Thermodynamic modeling shows that the deep waters are supersaturated with respect to siderite and pyrite. No other carbonates were found to be stable. This rare occurrence of siderite is symptomatic of the build-up of large concentrations of CO2 and Fe2+ in the Lake Nyos waters. A search for siderite in the deeper sediments could reveal the existence of previous gas burst events that have occurred at Lake Nyos or in other Cameroon lakes. © 1989.