The tectonic history of eastern North America is both long and complex. We have a good understanding of the many tectonic processes that have affected this region, but deep-seated deformational patterns are not well constrained. With the deployment of the Earth Scope USArray Transportable Array (TA), we have the opportunity to provide high-resolution seismological observations throughout North America.
For this project we utilized the data recorded on TA stations, as well as stations from the PASEIS network, to provide 76 shear wave splitting observations in and around Pennsylvania to better understand remnant lithospheric deformation from previous orogenic events. Our results suggest that some of the lithospheric deformational patterns in the Mid-Atlantic North American lithosphere predate the Appalachian orogeny and can be associated with Grenville deformation. For those less familiar with shear wave splitting, the line segments in the figure can be thought of as the orientation of mineral crystals about 200 km (125 miles) beneath the surface.
Please see our published results.