Newly Formed vs Reactivated Strike-Slip Faults in a Mud-Dominated Fold
Belt, Mackenzie Delta
Schoenborn, Greg1 (1)
Chevron,
The Mackenzie delta is located at the
lateral termination of the
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