2.2 Ga age of zircons in three occurrences of Upper Proterozoic clastic rocks of the northern Cassiar terrane, Yukon and British Columbia

Analyses of detrital zircons from three occurrences of Upper Proterozoic clastic rocks of the northern Cassiar terrane in Yukon and northern British Columbia yield a U–Pb age of 2224 ± 22 Ma. The zircons apparently belong to a single population similar in age to zircons in stratigraphically equivalent rocks of the southern Cassiar terrane and to zircons in rocks in the Yukon–Tanana terrane of Alaska. A source terrane or area of the required age and extent has not yet been identified.