The “Schistes carton” of Quercy (Tarn, France): a lithological signature of a methane hydrate dissociation event in the Early Toarcian. Implications for correlations between Boreal and Tethyan realms

  title={The “Schistes carton” of Quercy (Tarn, France): a lithological signature of a methane hydrate dissociation event in the Early Toarcian. Implications for correlations between Boreal and Tethyan realms},
  author={Laurent Emmanuel and Maurice Renard and Ren{\'e} Cubaynes and Marc de Raf{\'e}lis and Micha{\"e}l Hermoso and Laurence Lecallonnec and Antoine le Solleuz and Jacques Rey},
  journal={Bulletin De La Societe Geologique De France},
  • L. EmmanuelM. Renard J. Rey
  • Published 1 September 2006
  • Environmental Science, Geography
  • Bulletin De La Societe Geologique De France
The geochemical events (negative shifts in [sigma]13C and [sigma]18O, and Mn peak) associated with the "Schistes carton" of Quercy (SW France) do not appear to be due only to lithological variations and a differential diagenesis. They correspond to the Lower Toarcian global event and seem to be connected to a destabilization phase of gas hydrates. During its oxidation by seawater, the release of methane gas with a very low carbon isotopic ratio (- 60%) led to the production of CO2 and… 

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