Single-Crystal 40Ar/39Ar Dating of the Eocene-Oligocene Transition in North America
作者： C. C. Swisher , D. R. Prothero
DOI: 10.1126/SCIENCE.249.4970.760
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摘要: Explanations for the causes of climatic changes and associated faunal floral extinctions at close Eocene Epoch have long been controversial because of, in part, uncertainties correlation dating global events. New single-crystal laser fusion (SCLF) 40Ar/39Ar dates on tephra from key magnetostratigraphic fossilbearing sections necessitate significant revision North American late Paleogene chronology. The Chadronian-Orellan Land Mammal "Age" boundary, as a result, is shifted 32.4 to 34.0 Ma (million years ago), Orellan-Whitneyan boundary 30.8 32.0 Ma, Whitneyan-Arikareean now approximately 29.0 Ma. new shift Chron C12R Chadronian within interval, becomes age, Oligocene restricted Orellan, Whitneyan, early Arikareean. Eocene-Oligocene its climate change extinction events, correlates with not Duchesnean-Chadronian boundary.
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