Field Course Outline:
A full-day roadside field structural geology transect in the Laramide Orogeny of the Eastern Canadian Rockies, that will take place along the TransCanada Highway 1 from Calgary (AB) to Field (BC). The trip will include 8 to 10 stops and involve very short walking away from the vehicles. Stunning views of classic Rocky Mountain Geology features of the Laramide Orogeny in the Eastern Cordillera and Foreland Foothills belts, with explanations provided at each stop with useful diagrams and maps.
The structural architecture and evolution of compressive deformation will be discussed, throughout the Proterozoic to Tertiary stratigraphy. Influence of the mechanical stratigraphy on the deformation styles will be addressed for the Cretaceous clastic units in the Triangle Zone of the Foothills Belt and Paleozoic carbonaceous units in Front Ranges of the Cordillera Belt. Examples of localized accommodation features during folding, such as layer-parallel stretching and inner-arc fold compression will be shown.
Although the trip will be along the road, the leader will show the participants examples of along-strike deformation in the various mountain ranges and displacement transfer between thrust faults, using a collection of photos captured from hiking and climbing he did in the Kananaskis and Banff mountain parks over the last 30 years.
No hiking boots required, but binoculars and cameras will be good to have. An illustrated field guidebook will be provided.
Figure 1: View looking to the NW from the summit of Wind Tower toward the Bow Valley and Three Sisters Peaks (Big, Middle and Little) for Stop 3 of the field trip. The Rundle Thrust (RT) is outlined in yellow at the top of Wind Ridge in the foreground (red dotted line), and at the base of Little Sister Peak in the background. Trace of the footwall overturned syncline in the Jurassic units on Wind Ridge is shown in green over the mixed rock and treed area. The hangingwall section consists of a foreland-verging anticline-syncline pair in Paleozoic carbonate units. Abbreviations are RT = Rundle Thrust; Df = Devonian – Fairholme Group; Dp = Devonian – Palliser Formation; Mb = Mississippian - Banff Formation; Mr = Mississippian - Rundle Group.
Field Course Objectives:
1. Illustrate the main deformation features of the Laramide (Cretaceous) Orogeny in the Eastern and Main Ranges of the Canadian Rockies Belt, with thrusted and folded continental Paleozoic carbonate sequences overlain by the siliciclastic Mesozoic sequences of the foreland basin.
2. Get a general understanding of mountain belt evolution in the Front Ranges and observing good surface structural geology analogs of folded and fractured rocks explored and drilled in the subsurface of other thrust-fold belts.
3. Discuss the control of mechanical stratigraphy on the structural styles of compressive deformation, thrusting vs folding and presence of main detachment horizons.
4. Provide a visual representation of complexed leading-edge thrust sheet deformation, sometimes difficult to image and interpret on seismic data, both in the footwall and hanging wall compartments.
Figure 2: Stop 4 of the field trip. Panoramic view looking to the NW taken from the summit of Sulphur Mountain, above the Banff townsite. The TransCanada Highway 1 is outlined in red. We can see three of the major imbricate thrust sheets in the Front Ranges: the Rundle, Sulphur Mountain and Bourgeau Ranges. At this location the Rundle and Sulphur Mountain thrusts carry Upper Devonian Palliser carbonates in the immediate hangingwall, while Upper Cambrian carbonates are present in the immediate hangingwall of the Bourgeau thrust sheet. Foreland progression (SW to NE) of thrusting is evident - 15-25 degrees first order dips in Rundle Range, to second order (~35-45 degrees in Sulphur Mountain Thrust and vertical and third order (vertical to overturned) dips in Bourgeau Thrust are present. Progressive steepening of beds by younger, deeper thrust sheets is shown in the forward modelled three diagrams (Bégin and Veilleux, 2017; thrusts in red). Abbreviations are RT = Rundle Thrust; SMT = Sulphur Mountain Thrust; BT = Bourgeau Thrust; CA = Cambrian; Dp = Devonian – Palliser Formation; Mb = Mississippian - Banff Formation; Mr = Mississippian - Rundle Group; TR = Triassic.