Long-lived Panthalassic remnant: The Bridge River accretionary complex, Canadian Cordillera

International audienceNewly identified radiolarians from ribbon chert of the Bridge River complex in the southeastern Canadian Coast Mountains range in age from Mississippian to late Middle Jurassic. The Bridge River complex and the associated Cadwallader arc and Tyaughton and Methow basins lie between the Intermontane superterrane to the east and the Insular superterrane to the west. Triassic-Middle Jurassic development of the Bridge River subduction-aecretion complex records an important component of convergence between these superterranes. The time span represented in the Bridge River complex (-170 m.y.), one of the longest known age ranges for chert sedimentation, suggests that the Bridge River complex contains remnants of a long-lived, potentially far-traveled Panthalassic oceanic domain. Figure 1. Location map of Bridge River complex and main geologic units of south-central British Columbia (after Monger, 1986). Pattern indicates main chert-bearing complexes