SCHLISCHE, R. W.¹, M. O. WITHJACK², and G. EISENSTADT^2
1Rutgers University, Piscataway, NJ
²Mobil Technology Company, Dallas, TX

Abstract: Using Scaled Physical Models to Study Deformation Patterns Produced by Oblique-Slip Normal Faulting

The movement on reactivated faults is rarely either pure dip slip or strike slip. We used scaled physical models to study the deformation in the cover above a fault that is reactivated during oblique extension. The models consist of 4 cm of layered wet clay over a pre-cut 45° master fault striking at 45° to the horizontal component of fault displacement.

During the experiments, a highly faulted extensional forced fold forms in the clay layer above the master fault. Two fault populations develop in the cover sequence: one is subparallel to the trend of the underlying master fault; the other is subperpendicular to the horizontal component of fault displacement. The subparallel faults are mostly oblique-slip normal faults. This population increases with increasing depth and increasing deformation. The subperpendicular faults are mostly dip-slip normal faults. Commonly, these faults dip in the same direction as the master fault and, if overlapping, are separated from each other by well-developed relay ramps. Faults of the subperpendicular trend that dip opposite the master fault decrease in number with depth. Our work shows that hard fault linkage is strongly reduced in oblique-slip experiments compared to dip-slip experiments. Consequently, sediment and hydrocarbon migration pathways are potentially enhanced in oblique-slip fault zones relative to dip-slip fault zones. Deformation patterns observed in the models closely resemble those associated with oblique-slip normal faults from Australia, southeast Asia, and southeastern Canada.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas