REGIONAL OZARK TO OUACHITA TRANSECTS: A TECTONOSTRATIGRAPHIC FRAMEWORK

Cary Croneis published a set of regional cross sections across the Arkansas Arkoma Basin in the Arkansas Geological Survey Bulletin 3, 1930. These were based largely on surface geology projected into the subsurface. They were the first sections to truly illustrate the regional structural configuration of the Ouachita-Arkoma-Ozark transition. More than 50 years later in 1988, the Ft Smith Geological Society published a regional, E-W, stratigraphic cross section. This section was based on well log data and presented the subsurface stratigraphic nomenclature commonly used by the Oil and Gas industry to correlate cyclic pay zones in the Carboniferous succession throughout the region. The current study presents a new set of regional cross sections based on well logs and 2D seismic data that link the stratigraphic nomenclature from the FSGS section to the regional structural transects of Croneis. The sections are ~70 miles in length and include ~ 20,000ft of vertical stratigraphic thickness. Structural versions of these sections illustrate the deep, extensional structure overlain by the contractional, low angle thrusted structure of the Ouachita fold and thrust front. The three-stage tectonostratigraphic basin fill of the region is illustrated on a set of stratigraphic versions of these sections datumed on the Top Lower Atoka and the Top Middle Atoka. The three stages include a passive margin phase controlled by glacio-eustacy followed by a subsidence dominated, early foreland basin fill and a sediment supply dominated, late foreland basin fill. A series of paleogeographic reconstructions illustrate the tectonically controlled depositional evolution of the Arkoma Basin fill. In addition, these sections provide the framework for surface mapping projects that link subsurface to surface correlations leveraged with high resolution lidar data to add detail to regions of the state geologic map currently defined as “Atoka Undifferentiated”.