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Origin of transverse faulting, Rocky Mountain Front Ranges, Canmore, Alberta

Ian W. Moffat and John H. Spang
Origin of transverse faulting, Rocky Mountain Front Ranges, Canmore, Alberta
Bulletin of Canadian Petroleum Geology (June 1984) 32 (2): 147-161


A system of transverse faults, oriented at high angles to predominant northwest-southeast trending structures, is contained within the major Rundle and Sulphur Mountain Thrust Sheets of the Canadian Rocky Mountain Front Ranges near Canmore, Alberta. These transverse faults have been mapped in detail at a scale of 1:12,000. Structural observations at the megascopic, mesoscopic and microscopic levels have been used to develop a comprehensive kinematic model for the origin of transverse faults in this area. Shortening within the structurally lower Rundle Thrust Sheet was accomplished by folding and imbricate thrusting, whereas the overlying Sulphur Mountain Thrust Sheet was deformed solely by thrusting in the study area. Analysis of field data suggests that progressively eastward-advancing deformation, characterized by early thrusting in the Sulphur Mountain Sheet, was followed by folding and then thrusting in the Rundle Sheet. The transverse fault system consists of several minor transverse faults apparently restricted to the individual thrust sheets, as well as a major fault that offsets the Sulphur Mountain Thrust and terminates at a major hanging-wall imbricate in the Rundle Thrust Sheet. Interpretation of palinspastic cross sections through the Rundle Thrust Sheet, constructed for the time interval between folding and thrusting, suggests that the aforementioned imbricate thrust, against which the major transverse fault terminates, steepens rapidly northward from the transverse fault. This geometry determined that strata north of the transverse fault would be forced higher than their southern counterparts during thrusting, thus resulting in a transverse fold and, with further displacement, a transverse fault. Following the major faulting event, the combined thrust sheets were essentially separated into two distinct composite structural domains. As lock-up occurred along the lower bounding imbricate thrust, further shortening within the combined thrust sheets proceeded by sliding along pre-existing hanging-wall imbricate thrusts. This additional shortening contributes to the net slip observed across the major transverse fault in both the Sulphur Mountain and Rundle Thrust Sheets.

ISSN: 0007-4802
Serial Title: Bulletin of Canadian Petroleum Geology
Serial Volume: 32
Serial Issue: 2
Title: Origin of transverse faulting, Rocky Mountain Front Ranges, Canmore, Alberta
Affiliation: Univ. Calgary, Dep. Geol., Calgary, AB, Canada
Pages: 147-161
Published: 198406
Text Language: English
Summary Language: French
Publisher: Canadian Society of Petroleum Geologists, Calgary, AB, Canada
References: 38
Accession Number: 1985-011910
Categories: Structural geology
Document Type: Serial Map
Bibliographic Level: Analytic
Illustration Description: illus. incl. strat. col., sects., block diags.
Map Scale: 1:50,000
Map Type: structure contour map
N49°00'00" - N60°00'00", W120°00'00" - W110°00'00"
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2020, American Geosciences Institute.
Update Code: 1985
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