SKS SPLITTING AND UPPER MANTLE ANISOTROPY BENEATH THE SOUTHERN NEW ENGLAND APPALACHIANS: CONSTRAINTS FROM THE DENSE SEISCONN ARRAY

The crustal structure of eastern North America was created during two supercontinent cycles over the past 1.35 billion years. The present structure of the crust and mantle lithosphere beneath eastern North America preserves evidence of this complicated tectonic history, and new geophysical datasets are shedding light on its physical structure. Here we present seismic observations from the SEISConn array, a deployment of 15 broadband seismic stations across northern Connecticut. We studied the seismic waves that have passed through the upper mantle beneath southern New England, traveling nearly vertically beneath the seismic stations. Through measuring how these waves propagate differently in different directions (known as seismic anisotropy), we can learn about how past tectonic events have affected the deep part of the plate, and how the upper mantle is flowing today beneath southern New England. We find evidence for average fast splitting directions that are generally parallel to the absolute motion of the North American Plate. Additionally, there may be mantle upwelling (vertical flow) beneath the eastern portion of Connecticut today, and that the deep structure of the plate was altered by past tectonic events during Appalachian orogenisis.