Crustal Structure of the Northeastern United States: Contrasts Between Grenville and Appalachian Provinces

See allHide authors and affiliations

Science  09 May 1980:
Vol. 208, Issue 4444, pp. 595-597
DOI: 10.1126/science.208.4444.595


Average crustal models for the northeastern United States are computed on the basis of the travel times of P and S waves from regional earthquakes. The Precambrian Grenville Province in New York State has a relatively homogeneous crust. The Paleozoic New England Appalachians have a well-defined, two-layer crust that is slightly thicker and shows a high-velocity lower layer relative to the Grenville. A time-term analysis based on Pn data (waves refracted from the Moho) shows that a relatively thick or low-velocity crust parallels northeast-trending geologic structures in central New England. The observed differences between the two orogenic belts may reflect contrasts in their tectonic evolution.