%0 Journal Article %J Geological Magazine %D 1998 %T New Uppermost Cambrian U-Pb Date from Avalonian Wales and Age of the Cambrian-Ordovician Boundary %A Davidek, K. E. %A E. Landing %A Bowring, S. A. %A Westrop, S. R. %A Rushton, A. W. A. %A Fortey, R. A. %A Adrian, J. M. %K Cambrian–Ordovician boundary %K Late Cambrian %K North Wales %K U–Pb zircon age %X

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.

%B Geological Magazine %V 135 %P 305-309 %G eng %U http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=4489&fileId=S0016756898008711