FAULT-SLIP ANALYSIS ON MESOFAULTS OF THE STE. GENEVIEVE FAULT SYSTEM, HICKORY CANYONS STATE RECREATION AREA, EASTERN MISSOURI

We measured and studied the orientations, striae, and sense of shears of the faults cutting the Cambrian Lamotte Sandstone which are well exposed in Hickory Canyons State Recreation Area, eastern Missouri. On the state geological map, several faults are seen paralleling one strand of the Ste. Genevieve Fault System, which appears to be an active zone of intracontinental seismicity in the central United States, bounding the Ozark Dome to the west and the Illinois Basin to the east. I plotted GPS locations and measured fault orientations, slip directions (striae), and sense of shears of 32 mesofaults which are beautifully exposed in a network of deep box canyons. I interpret three families of faults and one family of joints; Family 1) N-S dextral strike slip faults with an average dip of 60 degrees, Family 2) E-W normal faults with average dips greater than 53 degrees, Family 3) E-W normal faults dipping 20 to 25 degrees, Family 4) NE-SW joints with near vertical plunge. We interpret that these faults are the result of distributed deformation related to a slightly inboard zone of transtension on the Ste. Genevieve Fault System within Ste. Genevieve County, Missouri.