The Geological Atlas of the Western Canada Sedimentary Basin

Chapter 16

Triassic Strata

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Figure 16.1

Index map of Triassic rocks in the Western Canada Sedimentary Basin.

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Figure 16.2

Total Triassic isopach map, with major producing fields highlighted (see tables 16.2a and 16.2b)

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Figure 16.3

Triassic structure map, and subcrop paleogeology.

Figure 16.4a

Northwestern portion of Atlas cross section A-A', in the Alberta Basin.

Figure 16.4b

Southeastern portion of Atlas cross section A-A', in the Williston Basin.

Figure 16.5

Cross section G-G*, showing the separation of the Williston Basin Triassic into the Watrous Sub-basin in the west and the Amaranth Sub-basin in the east, separated by the Birdtail-Waskada Axis.

Figure 16.6

Triassic nomenclature and correlation chart for the Alberta Basin portion of Western Canada Sedimentary Basin, from the Rocky Mountain Front Ranges, through the foothills to the Interior Plains, Alberta and British Columbia.

Figure 16.7

Schematic cross section illustrating Triassic formations, stratigraphic relations and depositional environments, Peace River Embayment area, northeastern British Columbia outcrop (SW) to the Peace River subsurface (NE), (modified from Gibson and Edwards, 1990b).

Figure 16.8

Generalized stratigraphic cross section, illustrating Triassic lithologies and regional relations between Rocky Mountain Front Ranges, foothills and subsurface plains of Alberta and British Columbia. Lithofacies assemblages 1, 2 and 3 correspond to broad regional transgressive-regressive packages and are related to relative sea-level changes. Major unconformities include the sub-Triassic, sub-Jurassic and sub-Cretaceous surfaces. The heavy black curve depicts relative sea level.

Figure 16.9

Schematic longitudinal section illustrating nomenclature and stratigraphic relations between Banff, Alberta (SE) and the Alaska Highway in northeastern British Columbia (NW) (prepared by E.T. Tozer, modified from Gibson and Barclay, 1989).

Figure 16.10

Model of inferred depositional environments for the Doig, Halfway and Charlie Lake formations, northeastern British Columbia. This scenario depicts progradation of a barrier-tidal inlet complex (Halfway Fm) over offshore shelf shale, siltstone and sandstone (Doig Fm). The barrier is capped by Charlie Lake sabkha facies (after Barclay and Leckie, 1986).

Figure 16.11

Cross section C-C*, Peace River Embayment. The datum is the top Halfway in the west and the sub-Jurassic unconformity in the east.

Figure 16.12

Cross section H-H', northeastern British Columbia to west-central Alberta. Datum is the top of the Halfway Formation, except at the extremities, where the sub-Jurassic unconformity is used as datum.

Figure 16.13

Cross section J-J', Pine River/Williston Lake outcrop in northeastern British Columbia to Clear Hills/Osborn subsurface, northwestern Alberta, west-southwest to east-northeast. The vertical scale is Atlas cross section standard (1:6000), but the horizontal scale is expanded.

Figure 16.14

Cross section K-K', Smoky River outcrop to Sturgeon Lake subsurface, west-central Alberta, southwest to northeast.

Figure 16.15

Typical spontaneous potential, gamma-ray, density and sonic response for the total Triassic succession in the Peace River Embayment and adjacent areas, Alberta and British Columbia. Vertical scale is 1:3000.

Figure 16.16

Type Montney Formation geophysical gamma-ray/density reference well logs (1:3000 vertical).

Figure 16.17

Geophysical gamma-ray/density logs of Montney Formation near subcrop edge (1:3000 vertical), illustrating four coarsening-upward, shale to sandstone cycles (units 1 to 4).

Figure 16.18

Geophysical and lithological reference well logs for the Doig and Halfway formations (see also on cross section K-K', Fig. 16.14). Note the abrupt contact between the Montney and Doig formations, the coarsening-upward character of the gamma-ray signature in the Doig Formation and the blocky gamma-ray profile of the Halfway Formation. Vertical scale is 1:3000.

Figure 16.19

Typical geophysical reference well logs of 'channel' sandstone in the upper Doig Formation (1:3000 vertical). Note the typical blocky character of the 'channel' sandstone and the abrupt and possibly unconformable contact with the overlying Halfway Formation.

Figure 16.20

Typical geophysical well log signatures of the Halfway Formation and contact signatures with the Doig and Charlie Lake formations. Upper and lower contacts of the Halfway may represent unconformities. Note the lithological signature of the Worsley Member. Note that the vertical scale (1:1500) is expanded from Atlas standard (1:3000).

Figure 16.21

Typical geophysical reference well logs of the lower Charlie Lake Formation, illustrating formal and informal members. Note that the vertical scale (1:1500) is expanded from Atlas standard (1:3000).

Figure 16.22

Typical geophysical reference well logs of the upper Charlie Lake Formation, illustrating formal and informal members. Note that the vertical scale (1:1500) is expanded from Atlas standard (1:3000).

Figure 16.23

Typical geophysical reference well logs of the Baldonnel and Pardonet formations. Note the two regionally distinct high gamma-ray kicks at the base of the Pardonet Formation, and the abrupt contact (unconformable) with the Jurassic Fernie Formation. Note that the vertical scale (1:1500) is expanded from Atlas standard (1:3000).

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Figure 16.24

Montney isopach map, and generalized lithofacies distribution.

Figure 16.25

Ring-Border Field area, illustrating the erosional edge of the Montney Formation and several small subparallel faults that offset the gas/water interface (after Sturrock and Dawson, 1990).

Figure 16.26

Stratigraphic dip section in the Montney Formation of the Ring-Border Field area, illustrating the sub-Cretaceous unconformity and hydrocarbon-bearing sandstones. Note the Cretaceous Gething Formation valley fill (after Sturrock and Dawson, 1990).

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Figure 16.27

Halfway-Doig isopach map, and generalized lithofacies distribution.

Figure 16.28

Schematic stratigraphic cross section illustrating: 1) probable unconformities between the Doig and Halfway and Charlie Lake formations; 2) blanket or continuous sandstone of the Halfway Formation; and 3) incised sandstone/coquina-filled channels in the upper Doig Formation (after Campbell et al., 1989).

Figure 16.29

Clean or gross sandstone isopach map showing bifurcating Doig Formation "channel" facies in the Sinclair Field of west-central Alberta.

Figure 16.30

Clean or gross sandstone isopach map of the barrier island shoreface and tidal inlet facies in the Halfway Formation in the Wembley Field, Alberta.

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Figure 16.31

Charlie Lake isopach map, and generalized lithofacies distribution.

Figure 16.32

Net pay isopach map of the Artex Member, lower Charlie Lake Formation, Brassey Field area, northeastern British Columbia (after Klein and Woofter, 1989).

Figure 16.33

Porosity isopach map (porosity less than 8%), showing thickness of productive and potentially productive occurrences of tidal flat and intertidal algal carbonates of the Boundary Member, Charlie Lake Formation, in Bonanza Field, northeastern British Columbia.