Paleomagnetic Constraints On Allochthonous Canadian Cordilleran Displacement: Results From Stikinia, British Columbia

In this study the Canadian Cordilleran displacements inferred from paleomagnetic results have been reevaluated by reviewing the existing data base with the addition of new data. Results from the Eocene Ootsa Lake Group yield a pole position which is statistically indistinguishable from published 50 Ma reference poles for North America. This is consistent with paleomagnetic results from Stikinia, Quesnellia, southern Wrangellia, and the Coast Belt indicating that much of the allochthonous CC had docked with the craton by 50 Ma.;Paleomagnetic directions from the Early Jurassic Telkwa Formation from this study confirm, with improved precision, the data obtained by Monger and Irving (1980). The reanalysis of the tectonic displacements indicated by all the CC Early Jurassic paleomagnetic data indicates that Terrane I, from the Permian to Early Jurassic, was in its present latitudinal position relative to the craton. Similar latitudinal concordance of southern Wrangellia with Terrane I and North America is suggested by the reanalysis of the Bonanza Group result.;The significant implication which has not been considered by previous large-scale northward displacement models is that the pre-Cretaceous data requires first large-scale southward displacement after the Early Jurassic. Paleomagnetic constraints from rocks with reasonable paleohorizontal control were provided by the Kasalka Group of this study and several other recent studies which support moderate ({dollar}\approx{dollar}1000 km) northward translation consistent with geologic estimates of maximum strike-slip along major CC transcurrent faults. Thus, the Cretaceous CC data is best explained by a CC displacement model in which moderate ({dollar}\approx{dollar}1000 km) northward translation has taken place, combined with local tilting of the Coast Belt intrusives and local block rotations principally in the Intermontane Belt. The solution to the tilt vs. translation controversy appears to be a combination of the two models. This interpretation has the desirable attribute of not requiring data selectivity as a prerequisite to the model as all the CC Cretaceous paleomagnetic results can be accommodated by this model. In addition, it is consistent with moderate post mid-Cretaceous northward displacements originally proposed by Monger and Irving (1980) and later reconfirmed by Armstrong et al. (1985)