Abstract – The intensity and extent of anoxia during the two Kellwasser anoxic events has been
investigated in a range of European localities using amultidisciplinary approach (pyrite framboid assay,
gamma-ray spectrometry and sediment fabric analysis). The results reveal that the development of the
Lower Kellwasser Horizon in the early Late rhenana Zone (Frasnian Stage) in German type sections
does not always coincide with anoxic events elsewhere in Europe and, in some locations, seafloor
oxygenation improves during this interval. Thus, this anoxic event is not universally developed. In
contrast, the Upper Kellwasser Horizon, developed in the Late linguiformis Zone (Frasnian Stage) in
Germany correlates with a European-wide anoxic event that is manifest as an intensification of anoxia
in basinal locations to the point that stable euxinic conditionswere developed (for example, in the basins
of the Holy Cross Mountains, Poland). The interval also saw the spread of dysoxic waters into very
shallow water (for instance, reefal) locations, and it seems reasonable to link the contemporaneous
demise of many marine taxa to this phase of intense and widespread anoxia. In basinal locations,
euxinic conditions persisted into the earliest Famennian with little change of depositional conditions.
Only in the continental margin location of Austria was anoxia not developed at any time in the Late
Devonian. Consequently it appears that the Upper Kellwasser anoxic event was an epicontinental
seaway phenomenon, caused by the upward expansion of anoxia from deep basinal locales rather than
an ‘oceanic’ anoxic event that has spilled laterally into epicontinental settings
