Publication Summary
Issue ID: GBCR2006-01-31
Title: Initiation and Deformation of the Jurassic-Cretaceous Bowser Basin: Implications for Hydrocarbon Exploration in North-Central B.C.
Author(s): Waldron, J.W.F., Gagnon, J.F., Loogman, W., Evenchick, C.A.
Purpose: The objectives of this paper are to improve understanding of the structural and sedimentological conditions during the initiation of Bowser Basin subsidence; and examine the Cretaceous-Tertiary deformation of the basin, with the goal of distinguishing and understanding deformation episodes in the Skeena fold belt.
Series Name: Geoscience BC Report
Publication Year: 2006
Other Citation Details: Geoscience BC Report 2006-1
Larger Work Citation: in Geological Fieldwork 2005, Geoscience BC Report 2006-01, pages 349 to 360
NTS Map Sheet(s): 093L, 093M; 094D, 094E; 103I, 103P; 104A, 104B, 104G, 104H
Place Keyword(s): British Columbia, Bowser Basin
Lat/Long (NSWE): 58, 56, -130.5, -127.5
Theme Keyword(s): Geoscience BC Fieldwork, Hazelton Group, Bowser Lake Group, structure, folds
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Abstract:
The Bowser Basin is a large (~53 000 km2) sedimentary basin located over the Stikine Terrane in the north-central Cordillera of British Columbia. The basin is filled by up to ~6 km of Jurassic to Cretaceous sedimentary rocks, mainly as signed to the Bowser Lake Group but potentially also including upper units of the Early to Middle Jurassic Hazelton Group, as well as Cretaceous strata of the Skeena Group in the southern part of the basin (Tipper and Richards, 1976; Ricketts et al., 1992; Bassett and Kleinspehn, 1997; Evenchick and Thorkelson, 2005). The economic significance of the basin includes, at the base, mineralized units (e.g., the Eskay Creek Au-Ag deposit; Anderson, 1993; Roth et al., 1999). Higher in the succession, the Bowser Lake Group contains significant coal beds and units with potential as petroleum source and reservoir rocks. The structure of the basin, dominated by folds, provides numerous potential traps. The petroleum potential of the basin has been discussed by Osadetz et al. (2003), and Evenchick et al. (2003). The aims of this study are to 1) improve understanding of the structural and sedimentological conditions during the initiation of Bowser Basin subsidence; and 2) examine the Cretaceous-Tertiary deformation of the basin, with the goal of distinguishing and understanding deformation episodes in the Skeena fold belt. Organic-rich shale units at the base of the succession deposited in the Bowser Basin were investigated by Ferri and Boddy (2005), who reported total organic carbon contents up to 6% in samples from mature to overly mature parts of the basin; they suggested that original organic contents may have been 24 times greater, representing the greatest source potential in the basin. An improved understanding of the stratigraphic and structural relationships of these rocks (objective 1) is therefore important for an assessment of the petroleum potential of the basin. Structurally, the Skeena fold belt contains overprinted folds of at least two generations, producing dome-and-basin fold-interference patterns (e.g., Evenchick 1991, 2001). Structural domes represent potential traps; an improved understanding of the origin and timing of folding, and the relationships between folds and faults (objective 2), may assist in the location of such structures in the subsurface. Fieldwork in 2005 focused on selected regions, chosen on the basis of previous mapping by Greig and Evenchick (1993), Evenchick et al. (2000), Evenchick (2001) and Evenchick and Thorkelson (2005) as displaying either field relations at the base of the Bowser succession or potential overprinting relationships between folds of different generations, or both. The results presented here are preliminary, and are based entirely on field results; thin section, paleontological and analytical work will be carried out later in the project.