TECTONIC CONTROL ON SEQUENCE ARCHITECTURE AND PRESERVATION BETWEEN THE PINE CREEK AND SKELLEY LIMESTONES (UPPER PENNSYLVANIAN), SOUTHEAST OHIO

The distribution of cyclic sedimentation within the distal Appalachian foreland basin was due to a combination of glacial-eustatic sea level changes and rates of subsidence. Preservation of any one transgressive-regressive event depends on the amount of accommodation generated by subsidence during sediment deposition. The interval of Upper Pennsylvanian strata between the Pine Creek (Dennis) and Skelley (Deer Creek) limestones in the distal Appalachian basin contains an anomalous number of marine units whose preservation has been linked to high rates of tectonic subsidence. High-resolution sequence stratigraphic analysis of one well-exposed roadcut through this interval just north of Athens, Ohio shows that there are nine cycles preserved, all of which are different in terms of thickness and types of marine and nonmarine facies present. Changes in total accommodation space between the Pine Creek and Skelley limestones interpreted from variations in thickness and the presence or absence of marine limestones and paleosols are generally consistent with the timing of tectonic subsidence inferred by Heckel et al. (1998). Comparison of this section to two nearby measured sections through the same interval, which are 3.9 to 4.3 km to the south, shows that the northern section was affected by local changes in subsidence resulting in an increase in total thickness of 153%. This increase in total accommodation is interpreted to be a result of a local structural downwarping produced by contemporaneous, low-amplitude folding in the region.