The influence of pre-existing basement structures on salt tectonics in the Upper Silurian Salina Group, Appalachian Basin, NE Pennsylvania: results from 3D seismic analysis and analogue modelling

The Upper Silurian Salina Group in Pennsylvania's Appalachian basin consists of several hundred feet of highly deformable and mobile salt that was a significant influence on the tectonic and structural development of the Appalachian Mountains during the late Paleozoic. Understanding how halokinesis and décollement thrusting of the Salina Group has contributed to the present-day structure of the Appalachian Basin is of intense current interest due to the energy resource potential of the overlying Marcellus Shale and underlying Utica Shale. Seismic data suggest that halokinesis of the Salina Group in the Appalachian Basin might be strongly influenced by the presence of preexisting faults in the underlying Neoproterozoic basement, which suggests that these structures may have interacted with the Salina Group or its interior during deformation. We examine these apparent interactions in more detail using high-resolution 3D seismic data from the Appalachian Basin of NE Pennsylvania to identify and characterize salt tectonic-related structures developed above and within the Salina Group during orogenesis, verify their geographic association with major basement faults, and document how reactivation of these preexisting faults might have influenced later deformation within and above the salt units. We also present the results of sandbox modelling of thin-skinned thrusting in a salt-analogue décollement. Multiple runs in the presence and absence of preexisting basement structures provide insight into how the modern structures observed in the seismic data initiated and evolved during progressively more intense orogenesis, and better constrain the physical processes that control the structural linkage through the Salina décollement.