A REASSESSMENT OF THE POSSIBLE ACTIVITY OF THE CRINER HILLS FAULT, SOUTH-CENTRAL OKLAHOMA

It has been suggested that there may have been Quaternary displacement along the Criner Hills fault, which is exposed at the ground surface in the Criner Hills, approximately 10 km southwest of Ardmore in south-central Oklahoma. The Criner Hills fault is generally on-trend with the active Meers fault (Crone and Luza, 1990), which has led some to suggest that the Criner Hills fault may also be active.

We have created a GIS database combining georegistered aerial photographs, satellite imagery, published geologic maps, and digital elevation models (DEMs) of the area around the surface trace of the Criner Hills fault. Through geological field work and analysis of the aerial imagery, geomorphic data and extant geologic maps, a new surface geologic map of the area has been compiled. Subsurface data from ~150 hydrocarbon exploration/production wells were used with the surface data to construct a 3D structural model of the volume that includes the Criner Hills fault, assisted by the structural modeling application LithoTect.

The Kirby fault is interpreted to be a major reverse fault, striking between ~320°-350° and dipping ~60°SW, that controls the topography and structure of the Criner Hills. We interpret the Criner Hills fault to be a secondary structure related to the Kirby fault. The Criner Hills fault strikes ~320° and dips ~80°NE, and may be associated with development of a "rabbit-ear" structure or backthrust within an anticline above the Kirby fault. The anticline probably originated as a fault-propagation fold. Our model accommodates ~6 km of displacement along the Kirby fault, and ~0.25 km of (primarily vertical) displacement along the Criner Hills fault. The Kirby fault cuts Cambrian rhyolite and the overlying Paleozoic cover sequence, and is cut by a lower Pennsylvanian unconformity, suggesting that it became inactive in the early Pennsylvanian after the end of the Wichita Orogeny. Cross-cutting relationships in the Hoxbar and Deese formations suggest that the Criner Hills fault was last re-activated during the late Pennsylvanian Arbuckle Orogeny, but accommodated only minor slip. We have not recognized any compelling data that support an interpretation of Quaternary activity along the Criner Hills fault.