Abstract

The Upper Jurassic Topley Intrusions intrude rocks of the tectonically stable Interior Plateau in central British Columbia. A stable primary remanent magnetization of both normal and reversed polarity was isolated after a.f. demagnetization in 19 of 22 sites (109 cores; 208 specimens) representing several of the plutonic units present in this sialic complex of quartz monzonite affinity near Endako, B.C. The unit mean remanence directions support some petrological correlations suggested by Carr, Bright, and White et al., but do not support others. The pole position derived from 13 sites representing 6 plutonic units with a K–Ar radiomelric age of 139 ± 4 m.y. (White et al.) is 128.6 °E, 70.0 °N(δm = 14.4°; δp = 11.4°). This position indicates a smooth polar wander path during the Jurassic between the well defined Upper Triassic and Lower Cretaceous pole positions. It also indicates that the northern Interior Plateau has not been tectonically rotated or translated since emplacement relative to the stable North American craton.

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