Jf. Bratton et al., Anoxia pre-dates Frasnian-Famennian boundary mass extinction horizon in the Great Basin, USA, PALAEOGEO P, 154(3), 1999, pp. 275-292
Major and trace metal results from three Great Basin stratigraphic sections
with strong conodont biostratigraphy identify a distinct anoxic interval t
hat precedes, but ends approximately 100 kyr before, the Frasnian-Famennian
(F-F, mid-late Devonian) boundary mass extinction horizon. This horizon co
rresponds to the final and most severe step of a more protracted extinction
period. These results are inconsistent with data reported by others from t
he upper Kellwasser horizon in Europe, which show anoxia persisting up to t
he F-F boundary in most sections. Conditions returned to fully oxygenated p
rior to the F-F boundary in the study area. These data indicate that the wo
rst part of the F-F extinction was not related directly to oceanic anoxia i
n this region and potentially globally. (C) 1999 Elsevier Science B.V. All
rights reserved.