La genèse des événements anoxiques de la période moyenne du Crétacé. Examen de l’hypothèse du méromictisme océanique
Year: 2001
Type: article
Abstract: The occurrence of oceanic anoxie events (OAE) during mid Cretaceous times have been explained by numerous hypotheses. Although the global tectonic effects constitute the frame in which these events take place, several authors have proposed different scenarios to explain it. Palaeogeographic, eustatic, climatic and trophic factors have been successively proposed since 25 years. The effects of an anoxic meromictism, due to volcanogenically derived carbon dioxide storage, have been recently suggested. In order to evaluate this latter hypothesis, the crust production of oceanic ridges and intraplate volcanic plateaus has been estimated for the major OAEs, and more specifically for OAE la (Early Aptian) and OAE 2 (Cenomanian-Turonian boundary). From these evaluations, the quantities of outgassing carbon dioxide have been calculated, for different duration in the case of the global ocean and the Atlantic ocean alone. These values are compared to the amounts measured in the modern maar-lakes from Cameroon, used to support the oceanic meromictism hypothesis. The results indicate that the duration necessary to reach the meromictism at both global or Atlantic scale are one or two magnitude-order higher than the duration of OAEs. The resulting carbon-dioxide concentrations are far from those observed in maar-lakes from Cameroon. Whatever the exact role of volcanogenic carbon dioxide in the genesis of OAE, it appears that a conjunction of causes is necessary, some of them being more crucial, such as superplumes and transgressions.
Authors: Jacques Sanfourche, François Baudin
Language: French
Subfield: Paleontology
Field: Earth and Planetary Sciences
Domain: Physical Sciences
SDG: Climate action
Open Access status: diamond
OpenAlex ID: W3113429366