Physical and biological events across the Frasnian–Famennian boundary in oxic carbonate successions in the Carnic Alps (Italy–Austria)

Two continuous carbonate sequences across the Frasnian–Famennian boundary in the Carnic Alps (Italy and Austria) have been studied intensively. According to conodont data, the sampled part of the Pramosio A section (Italy), ranges from Frasnian Zone 12 to Upper trachytera Zone. Around the F–F boundary this sequence, which is easily accessible for sampling, reflects a rather high sedimentation rate (centimetric scale per thousand years) in facies typical of an open shallow marine environment (shelf–shore) with a well ventilated bottom. The Freikofel T section (Austria–Italy border), ranging from Frasnian Zone 13a to Middle crepida Zone, is characterized by shallow-water to pelagic facies. Oxygen isotopes—measured on whole-rock and on conodont apatite—display conspicuous variations up-sequence conceivably corresponding to shortand medium-term climate changes.