Figure 18.1

Index map, showing locations of stratigraphic cross sections and localities mentioned in text.

Figure 18.2

Schematic maps of Western Canada (palinspastically restored) for: a. Early Jurassic (Sinemurian), b. Middle Jurassic (Early Bajocian) and c. Earliest Cretaceous (Berriasian) times, showing major changes of tectonic setting and sediment source direction (shown by arrows) in the epicratonic stratigraphic record.

Figure 18.3

East-west schematic cross section from southeastern British Columbia to Manitoba.

Figure 18.4

Correlation chart of the Jurassic and lowest Cretaceous formations in the Western Canada Sedimentary Basin. The representation of sporadically preserved Bathonian and Callovian sandstone and shale units in central Alberta is schematic. Stratigraphic placement of J1-J3 sands stems from Hopkins (1981).

Figure 18.5

Characteristic log responses for Jurassic (and, locally, lowermost Cretaceous) formations in: a. northeastern British Columbia, based on well d-97-I, 93-P-7; b. west-central Alberta, based on well 6-36-49-23 W5; c. southern Alberta, based on well 10-31-4-3 W4; d. southern Saskatchewan, based on well 4-32-2-20 W2; and e. southern Manitoba, based on well 13-20-4-27 W1.

Figure 18.6

East-west cross section C°-C* across northeastern British Columbia and northwestern Alberta. The shales that lie above the Lower Fernie ("Nordegg") limestone and shale unit are not subdivided in this transect (see also Fig. 18.7). The western two sections are generalized from unpublished descriptions by D.F. Stott of foothills outcrop sections. The pattern of colours depicting different interbedded lithologies in the Minnes Group do not imply detailed correlations.

Figure 18.7

East-west cross section H-H' across northwestern Alberta (from Poulton et al., 1990), parallel to and north of that shown in Figure 18.6. Palynological data from cores, combined with sample analyses, permit the recognition of a disconformity within the Fernie shales, at which Upper Jurassic shales overlie those of the Lower (and rarely Middle) Jurassic. Removal of the Poker Chip Shale below the Upper Jurassic in the westernmost well is unproven.

Figure 18.8

Northwest-southeast cross section A*-A** in northwestern Alberta, near the eastern erosional edge of the Jurassic. The Fernie shales probably include undifferentiable Poker Chip (Lower Jurassic) and Upper Fernie (Upper Jurassic) shales.

Figure 18.9

Northwest-southeast cross section J-J'from northwestern to west-central Alberta. The transect is west of A-A'(Fig. 18.8) and shows a more complete Jurassic section, in which detailed study of palynomorphs and samples permits subdivision of the Fernie Formation. Insets A and B show previous and alternative interpretations. Horizontal scale not consistent.

Figure 18.10

East-west cross section D°-D* in west-central Alberta.

Figure 18.11

Southwest-northeast cross section K-K'through west-central Alberta. This transect lies north of D°-D* (Fig. 18.10) and gives a different perspective on the distribution of Jurassic units. Individual sandstone and shale subunits of the Rock Creek Member are correlated in and around the Niton Field (inset).

Figure 18.12

East-west schematic cross section through west-central Alberta, from Bighorn Creek (west) to Gilby-Medicine River Field (east) (from Poulton et al., 1990). Superposed valley-fill sandstones in the east are adapted from Hopkins (1981).

Figure 18.13

East-west cross section F°-F' from southeastern British Columbia, across southern Alberta to south-central Saskatchewan. The western two sections include data from Gibson (1985). The colours depicting different interbedded lithologies in the Kootenay Group do not imply detailed correlations.

Figure 18.14

Northwest-southeast cross section A***-A', from southwestern to south-central Saskatchewan.

Figure 18.15

Easterly prograding clinothem model for correlation of Roseray sandstones, southwestern Saskatchewan, shown in correlated east-west stratigraphic cross section (from Christopher, 1966, 1974). The screening highlights individual depositional units.

Figure 18.16

Southwest-northeast cross section G-G* from south-central Saskatchewan to southwestern Manitoba.

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Figure 18.17

Structure contour map on the top of Jurassic or lowest Cretaceous units in the subsurface: top of Neocomian Nikanassin Formation or Minnes Group in northwestern Alberta and northeastern British Columbia; top of the Fernie Formation or Kootenay Group elsewhere in Alberta; top of the Vanguard Group in southern Saskatchewan.

Figure 18.18

Distribution and thickness of the Fernie Formation.

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Figure 18.19

Distribution, thickness and lithofacies of sub-Poker Chip (pre-Toarcian) units of the Fernie Formation (see Fig. 18.4). Thicknesses in northeastern British Columbia outcrops, generalized from published and unpublished data by D.F. Stott, suggest more irregularity than is shown.

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Figure 18.20

Distribution, thickness and lithofacies of Poker Chip Shale (Fernie Formation; mainly Toarcian). The Poker Chip is readily differentiated from higher shales of the Fernie Formation only where detailed paleontological data are available or where the Rock Creek sandstone separates the two. Contours elsewhere (between 54°30' and 55°N latitude) are estimated. Thicknesses north of 55° N latitude are perhaps slightly less than shown, because the unit mapped includes the lowermost of the beds that are now included in the Upper Fernie Formation (see Fig. 18.7). A thin Poker Chip equivalent may be present in northeastern British Columbia, but cannot be mapped there.

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Figure 18.21

Distribution, thickness and lithofacies of the Lower Bajocian Rock Creek Member and presumed (undated or poorly defined) equivalents in Williston Basin - the upper Watrous, upper Amaranth, Reston and lower Gravelbourg formations.

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Figure 18.22

Distribution and thickness of the Bajocian or probably Bajocian Sawtooth, Shaunavon, upper Gravelbourg, Red Jacket, and lower Melita formations, and the Highwood Member of the Fernie Formation.

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Figure 18.23

Distribution, thickness and lithofacies of the Bathonian and Callovian formations - the Rierdon, Roseray, Rush Lake, and upper Melita formations, and equivalent beds in the Fernie Formation. The distribution of small occurrences of Upper Bajocian, Bathonian, and Lower Callovian strata in the subsurface of west-central Alberta as far north as 54° 30'N latitude cannot be shown reliably at present.

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Figure 18.24

Distribution, thickness and lithofacies of the Upper Fernie Formation in western Alberta and northeastern British Columbia and the Swift, Masefield and Waskada formations in the southern Plains. The unit mapped in northwestern Alberta and perhaps also in northeastern British Columbia may contain thin, undifferentiated Poker Chip Shale equivalents in places. Data from the surface in northeastern British Columbia suggest more complicated distributions than the generalized map shows. The sandstone-rich Swift Formation in southeastern Alberta probably includes equivalents of the Success Formation, shown in Figure 18.25.

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Figure 18.25

Distribution, thickness and lithofacies of the uppermost Jurassic and lowest Cretaceous sandstone wedges of western Alberta and eastern British Columbia - the Kootenay and Minnes groups and the Nikanassin Formation; the Success Formation in Saskatchewan and the Deville Formation in the undeformed subsurface of Alberta. The distribution and thicknesses of the subsurface units in Alberta are incompletely known because of their inconsistent treatment in available databases, and because of uncertainties regarding their correlation. The Swift Formation in southern Alberta (see Fig. 18.24) probably includes some equivalents of the Success Formation that cannot be differentiated at present. The distribution of the Success Formation in eastern Saskatchewan suggests that equivalents must occur in Manitoba, where they have not been distinguished from the Swan River Formation. The chert components mainly indicate clasts in sandstones derived from Paleozoic rocks.

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Figure 18.26

Distribution and thickness of the Jurassic and lowest Cretaceous strata in Alberta (but not including Deville Formation) and British Columbia, and of the sub-Success Jurassic strata in Williston Basin. The Success and Deville formations (see Fig. 18.25) are included in the Mannville and Lower Mannville isopach maps (Hayes et al., this volume, Chapter 19).

Table 18.26a

Oil production from the Jurassic

Table 18.26a

Gas production from the Jurassic