New Uppermost Cambrian U-Pb Date from Avalonian Wales and Age of the Cambrian-Ordovician Boundary
|Title||New Uppermost Cambrian U-Pb Date from Avalonian Wales and Age of the Cambrian-Ordovician Boundary|
|Publication Type||Journal Article|
|Year of Publication||1998|
|Authors||Davidek, KE, Landing, E, Bowring, SA, Westrop, SR, Rushton, AWA, Fortey, RA, Adrian, JM|
|Keywords||Cambrian–Ordovician boundary, Late Cambrian, North Wales, U–Pb zircon age|
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.