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Salt Tectonics in the Upper Silurian Salina Group, Appalachian Basin, NE Pennsylvania: Results From 3-D Seismic Analysis and Analogue Modelling


The Upper Silurian Salina Group in Pennsylvania's Appalachian basin consists of several hundred feet of salt, which have been a significant influence on the tectonic and structural development of the Appalachian Mountains during the late Paleozoic. Understanding how halokinesis and décollement thrusting within the Salina Group has contributed to the present-day structure of the Appalachian Basin is of great importance due the organic-rich shale plays (Marcellus and Utica) currently being explored and developed within this region. Current seismic data indicate 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. These apparent interactions were investigated 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. The results of sandbox modelling of thin-skinned thrusting in a salt-analogue décollement, with multiple runs in the presence and absence of preexisting basement structures provide insight into how the modern structures observed in the seismic data formed and evolved during progressively more intense orogenesis. The proposed linkage between pre-existing basement structures and halokinetic processes during deformation of the Salina Group suggest that structures generated during previous tectonic episodes were an important control on the Paleozoic structural development of the Appalachian Basin; this may also be the case in other basins with similar tectonic and depositional histories.