Mountain building‐enhanced continental weathering and organic carbon burial as major causes for climatic cooling at the Frasnian–Famennian boundary (<i>c</i>. 376 Ma)?

Abstract

Abstract The Late Devonian was a period of drastic environmental changes, as exemplified by a major biotic crisis at the Frasnian–Famennian boundary (FFB) and the onset in Famennian times of glaciations across southern Gondwana. Worldwide evidence for the coeval development of the major Acadian–Eovariscan belt led us to propose a model relating the Late Frasnian–Famennian environmental perturbations to extensive continental uplift through two atmospheric CO 2 ‐depleting mechanisms: (1) the intensification of silicate weathering on the continental areas as attested by a major rise in the 87 Sr/ 86 Sr composition of sea water at the FFB; and (2) the massive burial of organic carbon (Kellwasser events) in partially confined basins due to the collisional‐induced reduction of equatorial oceanic communications between the Palaeotethysian and Panthalassic oceans. This process is also suggested to have been controlled by an important primary productivity connected to an increased nutrient availability triggered by the enhanced continental run‐off.