EVIDENCE FOR A DÉCOLLEMENT SOLED IN THE CHATTANOOGA SHALE IN THE SOUTHERN APPALACHIAN PLATEAU

To the northwest of the Wartburg basin (a region historically known for hydrocarbon production in Tennessee and Kentucky), trend surface residual anomaly (TSRA) maps illustrate deformational changes with respect to depth that may be caused by a décollement soled in the Chattanooga Shale. Horizons above the Chattanooga Shale TRSA map show pronounced linear trends parallel to regional strike, possibly indicating blind deformation associated with Alleghanian faulting. Mapped horizons below the Chattanooga Shale do not have these linear trends, signifying the units are below a detachment or that the trends were not able to be represented due to smaller amounts of data. Other detachment structures with more associated deformation and larger displacements are known to exist in the region (i.e., the Pine Mountain thrust and Cumberland Plateau overthrust). Hence, it is possible that a lower décollement is associated with these structures (e.g., the Cumberland Plateau overthrust could be soled in the Chattanooga Shale and ramp up-section into Mississippian and Pennsylvanian strata in different areas). This hypothesis could explain the tectonic stylolites identified west of Sequatchie valley, in Mississippian strata and faults soled in the Pennington Group (Mississippian) at Short Mountain, Tennessee. Lastly, the region northwest of the Wartburg basin corresponds to a possible small rift basin (identified in a Knox Group – basement isopach map) that connects with the Rome trough to the northwest. It is uncertain what role, if any, this structure had on petroleum sourcing, migration, and later deformation in the area.