Jurassic stratigraphy and history of north-central British Columbia

The Mesozoic rocks of north-central British Columbia are divided into five groups: the Upper Triassic basic volcanic Takla, the Lower to Middle Jurassic volcanic and sedimentary Hazelton, the mainly sedimentary Middle to Upper Jurassic Bowser Lake, the coal-bearing Lower Cretaceous Skeena, and the nonmarine Upper Cretaceous to Eocene Sustut. The Hazelton Group is subdivided into three formations, the Telkwa, Nilkitkwa, and Smithers, and these are further subdivided into several facies and members. The Hazleton Group accumulated in a nonmarine and marine basin, the Hazelton Trough, and, in the central Nilkitkwa Depression, up to 4200 m of marine volcanics and sediments accumulated. Intermittent but pervasive volcanism characterizes the group; transgressions and regressions throughout Hazelton time are recorded along the flanks of the trough; and subsidence by graben faulting in the Nilkitkwa Depression and en bloc movements of the entire trough persisted. The Hazelton Trough is one of several Early Jurassic basins of deposition in the Canadian Cordillera, which, with the exception of the Vancouver Basin, are still in their original positions relative to each other. In this report detailed information is rovided on the stratigraphy, paleontology, volcanic chemistry and physical characteristics, history, and paleogeography of the Hazelton Group.