A crystal-rich volcaniclastic sandatone in the lower Peltura scarabaeoides Zone at Ogof-odi 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 comparble to that provided by Ordovician graptolites and Mesozoic ammonites.
|Title||New uppermost Cambrian U-Pb date from Avalonian Wales and age of the Cambrian-Ordovician boundary|
|Authors||K. Davidek, E. Landing, S.A. Bowring, S. R. Westrop, A.W.A. Rushton, R.A. Fortey, J.M. Adrain|
|Publication Subtype||Journal Article|
|Series Title||Geological Magazine|
|Record Source||USGS Publications Warehouse|