Stratigraphic evidence indicating syndepositional faulting along the Cass fault system in the South Ozarks, Northwestern Arkansas

The Cass Fault system of north-central Arkansas is composed of monoclines and normal faults that strike in an east-west direction. This complex structural system forms a transitional boundary between the Arkansas structural platform to the north and the Arkoma basin to the south. Paleozoic strata of the structural platform are essentially horizontal. The Arkoma basin south of the Cass system is characterized by southward-dipping normal faults that extend into the Precambrian basement strata.;During the late Pennsylvanian Period, tectonic activity associated with the Ouachita orogeny created four main structural and physiographic areas illustrating the depositional activity: Ozark Uplift, North Arkansas Structural Platform (NASP), Arkoma Basin and the Ouachita Fold Belt. Based on additional investigation and the use of magnetic data throughout the region, more complex structures were noted. The Cass fault system is an example of one such complex structure in the region.;Due to the tectonic activity of the Cass system at the northern margin of the Arkoma basin, variable structural orientations are visible at land surface and influence the Cass present-day appearance. Previous investigations have provided insight regarding the depositional history, activity and geology of the Ozark Uplift, NASP, Arkoma Basin and the Ouachita Fold Belt. However, with regards to the Cass system, aside from its stratigraphy, there is a dearth of information available to the precise age of system.;Insofar as conflicting interpretations regarding the timing and degree of basin subsidence along and adjacent to the Cass fault system still exists. It was the intent of this thesis to determine and document a more precise timeframe regarding the depositional and structural history of the system. This documentation is based primarily on structural maps and borehole log interpretation.;Data interpretation and conclusions were derived based on the variations of Morrowan strata thickness, depicted during the correlation of wireline logs and structural calculations, example regional dip determination. Strata orientation indicated down-to-the-south faulting within the Cass system during the late Mississippian and early Pennsylvanian periods and other evidence useful for corroborating syndepositional faulting along the Cass.