CORRELATION OF THREE-DIMENSIONAL VARIATIONS OF SEISMIC MOHO WITH TECTONIC TERRANES IN THE NORTHERN APPALACHIAN MOUNTAINS

Teleseismic P-wave receiver functions are calculated to image the Moho variations in the northern Appalachian Mountains in order to explore its linkage with the geologically-defined surface terranes. Waveforms from 1995-2016 are analyzed for a total of ~200 broadband seismic stations. Consistent P-to-S phases converted at the Moho can be clearly observed. The phase arrival time shows a ribbon-shaped distribution pattern, which increases from the coastal plain northwestward to the Appalachian and Laurentian Plateaus. A distinct “sub-rectangular basin” anomaly of the Moho is observed in northern New Hamphire and western Maine. The Moho variation is roughly correlated with the Bouguer gravity anomaly and the NE-SW trending terrane boundaries. The spatial offset observed between the surface terrane boundaries and underlying Moho variations provides tight geophysical constraints on the three-dimentional distribution of accreted terranes within the crust, which significantly contribute to our understanding of the tectonic history in the northern Appalachian Mountains.