Metamorphic decarbonation, silicate weathering and the long‐term carbon cycle

The seawater 87 Sr/ 86 Sr curve implies a 50–100 Myr episodicity in weathering rate which requires a corresponding variation in CO 2 degassing from the solid earth to the atmosphere. It is proposed that this is caused by orogenesis, which both produces CO 2 as a result of metamorphic decarbonation reactions, and consumes extra CO 2 as a consequence of erosion‐enhanced weathering. Global climate on the geological time‐scale is therefore contTolled by the difference between the relatively large and variable orogenic‐moderated degassing and weathering CO 2 fluxes.