An investigation of P-wave reflectivity of the Southern Appalachian lithosphere using global seismic phases

The Southeastern Suture of the Appalachian Margin Experiment (SESAME) was designed to investigate the role of lithospheric deformation associated with Alleghanian collision and Mesozoic extension across the southeastern United States. In this study, we use zero-offset reflections generated by global seismic phases, PKiKP/PKIKP, as a virtual source to image lithospheric structure. Results from migrated images along the three profile lines of the SESAME array indicate Moho reflections from ~30 km beneath the Coastal Plain to ~45 km beneath the Blue Ridge and a lithosphere-asthenosphere boundary reflection at ~100 km. Two sets of reflectors with differing orientations, at Moho depths to ~70 km and ~70 km to ~100 km, likely indicate frozen anisotropy from fossil plate motion. Deeper reflections in the asthenosphere (~100-250 km) could indicate preserved present plate motion in the study area. These findings provide insight into the complex deformational history of the southern Appalachian system.