Belt-Purcell Basin: Keystone of the Rocky Mountain fold-and-thrust belt, United States and Canada

2007 ◽  
pp. 147-166 ◽  
Author(s):  
J.W. Sears
Keyword(s):  
United States ◽  
Rocky Mountain ◽  
Thrust Belt ◽  
Fold And Thrust Belt

A SEISMIC STRUCTURAL OVERVIEW OF LIARD BASIN, NORTHEAST BRITISH COLUMBIA, CANADA

2021 ◽  
pp. 1-53
Author(s):  
Jennifer Leslie-Panek ◽  
Margot McMechan
Keyword(s):  
British Columbia ◽  
Rocky Mountain ◽  
Structural Features ◽  
Boundary Structure ◽  
Thrust Belt ◽  
Western Canada Sedimentary Basin ◽  
Large Structures ◽  
Fold And Thrust Belt ◽  
High Level ◽  
Extensional Structures

The Liard Basin is an important sub-basin of the Western Canada Sedimentary Basin located in Northeast British Columbia along the eastern margin of the Canadian Cordillera. It contains significant potential unconventional gas resources but is largely underrepresented in public literature. Using available-for-purchase 2D seismic data, a regional structural interpretation of the basin was completed providing the first seismically controlled, high-level overview of the structural features of the basin and its surrounding area. The shape of the Liard Basin largely reflects the orientation of older Paleozoic and Proterozoic extensional structures that localized structures formed during Cretaceous - Tertiary compressive deformation. The eastern boundary of the basin is marked by the well-documented Bovie Structure. The Liard Anticline and the Liard River Anticline found near 60o N latitude are the only large structures located within the Liard Basin proper. Inversion of the herein named Liard Basin Boundary Structure, a west-side-down fault zone of Early Paleozoic age, localized the northwest boundary of the basin with the Liard Fold and Thrust Belt. A triangle zone bounds the Rocky Mountain Foothills and the Liard Basin to the southwest. Reflectors in the Proterozoic strata below the Liard Basin were deformed by compressive and then extensional structures prior to the deposition of Paleozoic strata. Proterozoic strata are involved in all the major structures of the adjacent Liard Fold and Thrust Belt, the Rocky Mountain Foothills and the Bovie Structure. These structures controlled the location of the Liard Basin.

Anomalous paleomagnetism of the Crowsnest Formation of the Rocky Mountains

1986 ◽  
Vol 23 (5) ◽  
pp. 591-598 ◽  
Author(s):  
E. Irving ◽  
P. J. Wynne ◽  
M. E. Evans ◽  
W. Gough
Keyword(s):  
North America ◽  
Early Cretaceous ◽  
Rocky Mountains ◽  
Remanent Magnetization ◽  
Rocky Mountain ◽  
Thrust Belt ◽  
Present Position ◽  
Paleosecular Variation ◽  
The Third ◽  
Fold And Thrust Belt

The volcanic Crowsnest Formation of Albian age (late Early Cretaceous) from the Rocky Mountain fold and thrust belt of Alberta has a stable remanent magnetization with a mean direction of 349°, 59 °(α95 = 5°) and paleopole at 78°N, 108°E(dm = 7°, dp = 5°). The inclination is lower than, and the declination clockwise of, the expected mid-Cretaceous paleogeomagnetic field for cratonic North America. Taken at face value the result indicates that the Crowsnest Formation and the thrust sheet in which it occurs have been transported from the south relative to cratonic North America by 17 ± 6 °(about 1800 km) and rotated 24 ± 10° clockwise. It is also possible that flattening of inclination is caused by magnetic anistropy, but tests show this to be unlikely. A third possibility is that the magnetization is secondary and of latest Cretaceous age, but there are good reasons for believing this is not so. Lastly, it is possible that the unit could have been formed close to its present position relative to the craton but was deposited so quickly that the paleosecular variation was not adequately sampled, and the result is only a "spot" reading of the paleofield. The last is our preferred interpretation of the flattened inclination, but the clockwise deflection of the declination could reflect rotation. Other paleomagnetic data from the fold and thrust belt are generally consistent with the third interpretation.

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