Rapid light carbon releases and increased aridity linked to Karoo-Ferrar magmatism during the early Toarcian oceanic anoxic event - INSU - Institut national des sciences de l'Univers Accéder directement au contenu
Article Dans Une Revue Scientific Reports Année : 2022

Rapid light carbon releases and increased aridity linked to Karoo-Ferrar magmatism during the early Toarcian oceanic anoxic event

Eric Font
  • Fonction : Auteur
Luís Vítor Duarte
Mark J. Dekkers
  • Fonction : Auteur
Ramon Egli
Jorge E. Spangenberg
  • Fonction : Auteur
Joana Ribeiro
  • Fonction : Auteur
Elsa Gomes
  • Fonction : Auteur
José Mirão
  • Fonction : Auteur
Thierry Adatte

Résumé

Large-scale release of isotopically light carbon is responsible for the carbon isotope excursion (CIE) of the Toarcian Oceanic Anoxic Event during the Lower Jurassic. Proposed sources include methane hydrate dissociation, volcanogenic outgassing of carbon dioxide and/or thermogenic methane release from the Karoo-Ferrar magmatic province (southern Africa). Distinct small-scale shifts superimposed on the long-term CIE have been interpreted as rapid methane pulses linked to astronomically forced climate changes. In the Peniche reference section (Portugal), these small-scale shifts correspond to distinct brownish marly layers featuring markedly high mercury (Hg) and magnetic mineral concentration. Total organic carbon and Hg increase are uncorrelated, which suggests input of Hg into the atmosphere, possibly released after the intrusion of the Karoo-Ferrar sills into organic-rich sediments. Enhanced magnetic properties are associated with the presence of martite, washed-in oxidized magnetite, inferred to be due to increased aridity on the continental hinterland. This study provides strong evidence for a direct link between the Karoo-Ferrar magmatism, the carbon-isotope shifts and the resulting environmental changes.
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insu-03691309 , version 1 (09-06-2022)

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Eric Font, Luís Vítor Duarte, Mark J. Dekkers, Celine Remazeilles, Ramon Egli, et al.. Rapid light carbon releases and increased aridity linked to Karoo-Ferrar magmatism during the early Toarcian oceanic anoxic event. Scientific Reports, 2022, 12, ⟨10.1038/s41598-022-08269-y⟩. ⟨insu-03691309⟩
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