CRUSTAL STRUCTURE OF NORTH AMERICA AND THE ADJACENT OCEAN BASINS

Since the 1960s, compilations of seismic data have been used to construct maps of properties of the Earth’s crust and mantle. We present new maps of the seismic properties of North America and the surrounding ocean basins, including contour maps of: 1) crustal thickness (hc); 2) average crustal p-wave velocity (Pc); 3) average p-wave velocity of the consolidated or crystalline crust (Pcc); and 4) sub-Moho p-wave velocity (Pn). Our crustal thickness map for North America and the surrounding ocean basins was recently updated using a database of about 2000 data points. One new feature of this map is an extension of the thin crust of the Basin and Range Province into Western Canada. We also find a close correspondence between high average crustal velocity and accretionary and magmatic orogenies.(e.g., Trans-Hudsonian, Grenvillian, Acadian, Appalachian, the Cascades, and the Alaskan Range). In contrast, there are a number of interesting anomalously low average crustal velocities in the Basin and Range Province, the Snake River Region, and the Northwest Territories of Canada. Many of these are regions of active or recent extensions or hotspot activity.