Mid-Atlantic Coastal Plain and Continental Margin: Basement and Mantle Structure and Continent-Ocean Transition
R.E. Sheridan, D.L. Musser, W.S. Holbrook, L. Glover, III, 1995. "Mid-Atlantic Coastal Plain and Continental Margin: Basement and Mantle Structure and Continent-Ocean Transition", E-3 Southwestern Pennsylvania to Baltimore Canyon Trough
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The U.S. Mid-Atlantic continental margin was the site for the third project of EDGE, a program for seismic-reflection studies of the submerged continental lithosphere (Fig 1). The passive continental margin of eastern North America contains the roots of the Appalachian orogen which play a role in the formation of the modern margin. Consequently, the seismic data image major Appalachian structures as well as rift and drift structures. The EDGE transect includes a 560 km grid of seismic-reflection profiles MA 801-804 (Fig. 1). The grid is complemented by existing U.S.Geological Survey (USGS) line 28. The shots were recorded on 10 ocean bottom receivers (Holbrook and others, 1992,1993a) and 11 portable land seismic stations.
Several other recent seismic experiments have focussed on the poorly understood structural change across rifted continental margins. One of the most intriguing discoveries is the apparently widespread existence of usually high lower-crustal seismic velocities (7.2–7.4 km/s) in the continent-ocean transition zone (Diebold and others, 1988; Trehu and others, 1989a, b; Austin and others, 1990). These high velocities have been interpreted as evidence of voluminous magmatic underplating just prior to the initiation of seafloor spreading (White and others, 1987; White and McKenzie, 1989). In order to measure the amount of material that has been added to the crust of a continental margin by magmatism during rifting and breakup, accurate knowledge of the margin crustal structure is needed. The EDGE seismic data provide that information on the U.S. Atlantic continental margin. The data were collected off northern Virginia during the
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DNAG Transect E-3. Part of GSA’s DNAG Continent-Ocean Transect Series, this transect contains all or most of the following: free-air gravity and magnetic anomaly profiles, heat flow measurements, geologic cross section with no vertical exaggeration, multi-channel seismic reflection profiles, tectonic kindred cross section with vertical exaggeration, geologic map, stratigraphic diagram, and an index map. All transects are on a scale of 1:500,000.