Abstract

Bovie Structure, which marks the eastern limit of Upper Cretaceous strata in the Liard Basin, is interpreted from seismic and well data to be a product of two major stages of development: the first, crustal uplift and compression during the late-Carboniferous to early Permian; the second, horizontal convergence during the Laramide Orogeny. North of Trout Lake Fault zone the second phase involved a shallow décollement fault whereas south of Trout Lake Fault zone, Laramide stresses may have caused transpressional movement on the crustal scale fault and development of a ‘flower’ structure. Bovie Fault, which has long been considered to be extensional, is here interpreted to be convergent and a product of the earlier uplift.

The structure is here divided into three zones—northern and central zones, which lie north of Trout Lake Fault zone, and a southern zone. The central zone, where Bovie Structure is most fully developed, contains Bovie anticline, which is seen at surface as a chain of three N–S striking ridges. This anticline is interpreted to consist of blocks of Carboniferous strata that first have been uplifted on a west-directed, steeply-dipping, crustal-scale thrust fault. Then, during the Laramide Orogeny, blocks of these Carboniferous strata were severed and carried eastward on the shallow detachment of the Bovie Lake Thrust.

Bovie Fault rapidly diminishes northward across the northern zone until the remaining basement strain is transferred eastward to a second, smaller en échelon fault. In this zone, strata are interpreted to have responded to uplift of the eastern block with a combination of faulting and monoclinal folding. There is no evidence of a shallow Bovie Lake Thrust detachment in the northern zone.

Southward, Bovie Structure turns abruptly southwest across the Trout Lake Fault zone, and the west-directed deep fault steps eastward in an en échelon manner. In the southern zone, there is little evidence for a shallow-detachment fault, and the second phase of development is interpreted to be one of transpressional reactivation of the west-directed, crustal-scale fault producing ‘flower’ structures.

Uplift on Bovie Fault may have coincided with uplift of Celibeta High, which developed immediately east of Bovie Structure. Adoption of a two-stage contractional model has led to the identification of new conceptual plays on Bovie Structure.

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