Upcoming Division Events
An overview of the Chinook compilation map series, SW Alberta and SE B.C.
Speakers: Glen S. Stockmal | Geological Survey of Canada
Location: Schlumberger Palliser One Building, 200, 125 - 9th Ave SE Calgary
Date: March 07, 2019 | 12:00 noon
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Fig. 1. Locations of the Chinook map sheets. Base map is a portion of Wheeler and McFeely (1991: GSC Map 1712A). NTS numbers of 1:50k topographic sheets are indicated.
The Chinook GIS compilation map series, compiled at a nominal scale of 1:100,000 on 1:50,000-scale topographic bases, comprises three GSC open files (7475, 7476, and 7477) that encompass twenty-six 1:50,000-scale map sheets in the Rocky Mountains and Foothills of southwestern Alberta and southeastern British Columbia (Fig. 1). Source maps and other data used in compilation include GSC and provincial survey maps and reports, published page figures, unpublished thesis maps, unpublished GSC field notes, aerial photos, and field maps, as well as spot field checking. Revision and reinterpretation during compilation involved extensive use of Google Earth™ and traditional aerial photograph imagery.
The most intensive revisions or reinterpretations of source maps and other data were made to the following areas or features, listed approximately from foreland to hinterland:
1. Fault and fold linkages and associations in the Foothills encompassed by GSC NATMAP open files south of Castle River.
2. In the hanging walls of the Livingstone Thrust and Station Creek Fault.
3. In the footwall of the Lewis Thrust, including the Oyster Syncline, the Etherington Creek Fault, and the Carbondale River–Goat Creek structure.
4. The controversial Howell Creek and Squaw Creek structures.
5. Structures bounding, within, and north of the Fernie Basin, adjacent to Wisukitsak Range and Erickson Ridge, where the Fernie Formation hosts the Fernie and West Line Creek detachments.
6. The Bourgeau Thrust – inferred to terminate at the town of Elkford, B.C.
7. The Hosmer Thrust sheet – reinterpreted as two or possibly three distinct fault slices, where the underlying thrusts merge upward with the Fernie Detachment.
8. The Gypsum Fault – formerly interpreted as the Bull River Thrust but reinterpreted as a folded, east-dipping, and east-directed detachment that separates folded sub-Devonian strata of the inverted White River Trough from overlying Devonian and younger strata.
9. The structure from Mount Broadwood northward to Mount Hosmer – reinterpreted as a blind thrust stack between the Fernie Detachment above and two overlapping detachments below: beneath the Middle Aldridge Formation in the south and the Gypsum Fault in the north.
10. Structures along Inverted Ridge, including the Hefty and Macdonald faults (the former was previously interpreted as a thrust, but is reinterpreted as a normal fault).
Some of these reinterpretations offer comprehensive solutions to well-known enigmatic structures (e.g., Howell Creek, Carbondale River – Goat Creek, Hosmer Thrust), some reconcile confusing, problematic, or contradictory previous interpretations (e.g., multiple structures on NATMAP Foothills maps), whereas others offer new views of supposedly well-understood features (e.g., Wisukitsak Range and Erickson Ridge, Bourgeau Thrust, Hefty and Macdonald faults). This overview of the Chinook compilation maps will touch briefly on each of these areas or features.
Glen Stockmal received a B.Sc. from the University of Manitoba (1977), an M.Sc. from the University of Calgary (1979), and a Ph.D. from Brown University (1983). Following a post-doctoral fellowship at Dalhousie University, in 1985 he joined the Geological Survey of Canada in Dartmouth, N.S. In 1991, having endured a dozen years living out of sight of the Rockies, he transferred to the GSC’s Calgary office, where he has been involved in a variety of structural geology activities. He was Editor-in-Chief of the Bulletin of Canadian Petroleum Geology from 2004 to 2009, and received a CSPG Tracks Award for his service.