FAULTING WITHIN THE HORSE CREEK STRUCTURE OF NORTHEASTERN OKLAHOMA?

A moderate-resolution (10m) digital elevation model along with field observations allow re-evaluation of the Horse Creek structure in Northeastern Oklahoma. This structure was previously identified as an asymmetric, southeast-vergent fold called the Horse Creek anticline (Siebenthal, 1907). The Horse Creek structure is a prominent, ENE-trending, ~80km long, arcuate topographic escarpment passing through Mayes, Craig, Delaware, and Ottawa Counties with maximum local relief of ~65m (200ft). The Horse Creek structure lies within a regionally extensive exposure of Lower Mississippian strata (Keokuk, Reed Springs, St. Joe Group and equivalents), but a linear isolated band of Upper Mississippian strata (Pitkin, Fayetteville, Batesville, Hindsville, and Moorefield Formations) marks the base of the escarpment for a distance of ~60 km. Through preliminary examination of field relationships and groundwater wells, the structure has been documented to have ~10 degrees of dip and is classified as an asymmetric fold along the exposed western section of Horse Creek. The Horse Creek structure intersects the NE-striking Seneca fault near the convergence of the Neosho and Elk Rivers. The axis of the Horse Creek anticline and the Upper Mississippian strata appear to be offset by the Seneca fault in an apparent dextral sense. This could potentially show that the Horse Creek structure is older than the Seneca fault. Although the Horse Creek structure was originally mapped as a regional contractional asymmetric fold, the current observations suggest there may be unrecognized faulting along the SW and NE sections of the Horse Creek structure. Through further analysis of petroleum exploration, and groundwater wells in the area around the Horse Creek structure, it should be telling in testing the fault origin of the SW and NE sections of the Horse Creek Structure. Acquisition of shallow seismic reflection data should test the hypothesis of a fault-related origin for the structure.