Sedimentology and stratigraphy of a continental terrace wedge: the Lower Cambrian Sekwi and June Lake formations (Godlin River Group), Mackenzie Mountains, Northwest Territories, Canada

• Main Author: Krause Schroeder, Federico Fernando
• Other Authors: Oldershaw, Alan E.
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: University of Calgary 1979
• Subjects: Geology; Stratigraphic - Cambrian; Geology - Northwest Territories - Mackenzie Mountains; Sedimentation and deposition; Canada; Godlin River; Northwest Territories; Selwyn; Mackenzie mountains
• Online Access: http://hdl.handle.net/1880/15557; https://doi.org/10.11575/PRISM/10856

Bibliography: p. 219-244. There are oversized diagrams at the end of the thesis. Lower Cambrian sedimentary rocks exposed in the Western Mackenzie Mountains are present over an area of approximately 50000 sq. km. They represent a continental terrace wedge that evolved during the Lower Cambrian on the northwestern flanks of the North American continent. The continental terrace wedge belongs to the Mackenzie Platform and Selwyn Basin and is located west of the Mackenzie Arch. Strata of the continental terrace wedge comprise two formations: June Lake (new) and Sekwi (redefined). The Lower Cambrian rocks can be further described in terms of five major depositional regimes: (1) Tidal and supratidal deposits - muddy and peloidal dolostones and limestones with cryptalgal fabrics, dessication cracks, karst, Runzel marks, intraclasts, fenestral textures, ripple marks, crossbeds, fossil coquinas and bioturbation; (2) Intertida, shallow subtidal, slope and rise deposits - micritic, peloidal and bioclastic limestones and dolostones with shaly interbeds. The deposits are characterized by bioturbation, early cementation, turbidites and breccia beds; (3) Oolite shoal deposits- oolitic, oncolitic, bioclastic packstones and grainstones which can be further subdivided into two Subfacies I and II. Subfacies I is characterized by plane parallel beds, is typically developed at the base of the oolite facies, and is interbedded with bioturbated horizons and bioclastic archeocyathid-Renalcis sp. boundstones. Interpreted as a product of relatively deep or low energy conditions of deposition, Subfacies I is generally succeeded by high angle crossbedded lithologies of Subfacies II which reflect higher energy conditions and constant agitation; (4) Submarine slope and fan deposits - dark brown shaly siltstones with fine grained sandstone interbeds. These deposits are characterized by plane parallel, wavy and ripple cross-laminations, load casts, lenticular bedding and graded layers. Breccia beds with shelf-derived clasts and isolated ...