Crustal structure of the western New England Appalachians and the Adirondack Mountains

Presents an interpretation of the crustal velocity structure based on a seismic refraction/wide-angle reflection experiment in eastern North America extending from the Adirondacks in New York State through the northern Appalachians in Vermont and New Hampshire to central Maine. Modeling of the eastern portion of the profile within the New England Appalachians shows a subhorizontal layered crust with upper crustal velocities ranging from 5.5 to 6.2 km/s, a midcrustal velocity of 6.4 km/s, and a lower crustal velocity of approximately 6.8 km/s. Crustal thickness increases from 36 km beneath Maine to 40 km in Vermont. This experiment provides further evidence for the obduction of the allochthonous western Appalachian units onto Grenvillian crust above the azone of detachment that penetrates at least to midcrustal depths and was the locus of successive Paleozoic thrusting. -from Authors