New uppermost Cambrian U–Pb date from Avalonian Wales and age of the Cambrian–Ordovician boundary

A crystal-rich volcaniclastic sandstone in the lower Peltura scarabaeoides Zone at Ogof-ddû near Criccieth, North Wales, yields a U–Pb zircon age of 491∓1 Ma. This late Late Cambrian date indicates a remarkably young age for the Cambrian–Ordovician boundary whose age must be less than 491 Ma. Hence...

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Veröffentlicht in:Geological magazine 1998-05, Vol.135 (3), p.303-309
Hauptverfasser: DAVIDEK, K., LANDING, E., BOWRING, S. A., WESTROP, S. R., RUSHTON, A. W. A., FORTEY, R. A., ADRAIN, J. M.
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Sprache:eng
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Zusammenfassung:A crystal-rich volcaniclastic sandstone in the lower Peltura scarabaeoides Zone at Ogof-ddû near Criccieth, North Wales, yields a U–Pb zircon age of 491∓1 Ma. This late Late Cambrian date indicates a remarkably young age for the Cambrian–Ordovician boundary whose age must be less than 491 Ma. Hence the revised duration of the post-Placentian (trilobite-bearing) Cambrian indicates that local trilobite zonations allow a biostratigraphic resolution comparable to that provided by Ordovician graptolites and Mesozoic ammonites.
ISSN:0016-7568
1469-5081
DOI:10.1017/S0016756898008711