--> Abstract: Newly Formed vs Reactivated Strike-Slip Faults in a Mud-Dominated Fold Belt, Mackenzie Delta; #90063 (2007)

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Newly Formed vs Reactivated Strike-Slip Faults in a Mud-Dominated Fold Belt, Mackenzie Delta

 

Schoenborn, Greg1 (1) Chevron, San Ramon, CA

 

The Mackenzie delta is located at the lateral termination of the Brooks range against the Canadian shield. Abundant 2D seismic lines of various vintages, several new 3D cubes, and numerous wells provide a good database to decipher the multiphased structural evolution of the area.

 

In much of the delta geometric relationships of anticlines, strike-slip faults, and normal faults to each other are very predictable, despite local rotations of stress directions. Steep faults trending at a 60deg angle to anticlinal axes look like normal faults in vertical seismic sections, but in many cases the predicted strike-slip components can be verified and quantified by offset channels on horizon slices or even timeslices. Most strike-slip faults are short and straight.

 

In other areas, however, strike-slip faults reactivated pre-existing normal faults that originated as Early Cretaceous rift faults or as Early Tertiary collapse faults in the quickly growing delta. These reactivated faults do not follow such a well organized pattern, with left-lateral and right-lateral fault-trends separated by as little as 5deg. They tend to be much longer and not as straight as the newly formed strike-slip faults. Irregularities give raise to releasing and restraining bends, several of which are beautifully imaged in 3D. Despite these complexities, fault geometries in this mud-dominated region are much simpler than many reactivated fault systems in better lithified rocks.

 

AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California