Abstract

The lower Paleozoic strata of the Northern Canadian Cordilleran Miogeocline document a non-passive tectonic evolution of the rifted northern margin of Laurentia. The stratigraphy of the Kechika Formation, Road River Group and Skoki Formation in northern British Columbia has been described previously during reconnaissance mapping. This study provides detailed stratigraphic descriptions of Upper Cambrian to Lower Silurian units from 9 key sections which span an east-west transect from the Macdonald Platform to the Kechika Trough, and 3 sections across the parautochthonous Cassiar Terrane. The transect lies within an interpreted upper plate of an asymmetrically rifted margin. Regionally, renewed phases of extension of the margin throughout the lower Paleozoic are recorded in abrupt lateral and vertical facies changes and pulses of volcanism. The tectono-stratigraphic framework was influenced by eustatic sea-level changes.

Revised stratigraphic terminology proposed herein includes the division of the Kechika Formation into 5 formal members: the Lloyd George, Quentin, Grey Peak, Haworth and Mount Sheffield members. The Skoki Formation comprises three distinct, formal members defined as the Sikanni Chief, Keily and Redfern members. The Road River Group is divided into three new formations: the Ospika Formation, the Pesika Formation (formerly the Silurian Limestone) and the Kwadacha Formation (formerly the Silurian Siltstone). The Ospika Formation is further subdivided into five formal members: the Cloudmaker, Finlay Limestone, Chesterfield, Finbow Shale and Ware members.

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