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New Uppermost Cambrian U-Pb Date from Avalonian Wales and Age of the Cambrian-Ordovician Boundary

TitleNew Uppermost Cambrian U-Pb Date from Avalonian Wales and Age of the Cambrian-Ordovician Boundary
Publication TypeJournal Article
Year of Publication1998
AuthorsDavidek, KE, Landing, E, Bowring, SA, Westrop, SR, Rushton, AWA, Fortey, RA, Adrian, JM
JournalGeological Magazine
Volume135
Pagination305-309
KeywordsCambrian–Ordovician boundary, Late Cambrian, North Wales, U–Pb zircon age
Abstract

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.

URLhttp://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=4489&fileId=S0016756898008711