The onset of the Permo-Carboniferous glaciation: reconciling global stratigraphic evidence with biogenic apatite delta O-18 records in the late Visean: Reconciling global stratigraphic evidence with biogenic apatite δ ¹⁸ O records in the late visean

The delta O-18 values of phosphatic microfossils recovered from NW Ireland are used to determine the timing and magnitude of cooling associated with the onset of the Carboniferous glaciation. Microfossil fish delta O-18(apatite) demonstrates a + 2.4% (V-SMOW) shift, which, once corrected for delta O-18(seawater) changes owing to evolving ice volumes, equates to an approximate 4.5 degrees C reduction in equatorial sea surface temperature between the earliest Asbian and the midBrigantian (late Visean). Both conodont and microfossil fish delta O-18(apatite) indicate stabilization of an icehouse climate during the Brigantian and into the Serpukhovian. Substantial late Visean cooling identified herein is in good agreement with global glacioeustatic records.