The reprocessing and extended interpretation of seismic reflection data recorded over the Hayesville-Fries thrust sheet in southwestern North Carolina

Reprocessing of Appalachian Ultradeep Core Hole (ADCOH) southern Appalachian seismic reflection data was focused on improving the reflection imaging and hence interpretability of seismic signatures previously interpreted as duplexes created by thrust stacking of thin beds of Paleozoic shelf strata. The reprocessed data are used to determine a more unique depth domain geometry for one of the proposed duplexes. Reprocessed data are partially improved through an increase in both stacking velocity coverage and datum statics velocity coverage as well as an appropriate use of residual statics. Interpretability increases from the improvement in resolution and the consideration of geologic strike direction relative to profile direction. Initial shotpoint ray trace modeling shows the chaotic nature of raypaths and some of the problems associated with the imaging of reflections when complex geology is involved. Data reprocessing and two-dimensional ray trace modeling yield results which suggest that the studied seismic signature is part of a broad hinterland-dipping duplex. At the trailing edge of the duplex itself beds appear to be successively fault truncated, perhaps explaining the increased amplitude and reflectivity in this zone. The truncations result in a wedge-shaped geometry that resembles the trailing edge of an antiformal stack duplex. The improved data also show 1) a shallow band of reflections that correlate with the Shope Fork and Chunky Gal Mountain faults within the Blue Ridge allochthon, 2) thrust ramping initiated by basement faulting that extends only a short distance into the overlying sedimentary strata, 3) a more highly faulted Grenville basement surface and, 4) almost intact Paleozoic shelf strata (?) being carried along the thrust surface serving and bounding the hinterland-dipping duplex.