High-sensitivity aeromagnetic survey of the U.S. Atlantic continental margin

The U.S. Geological Survey contracted a high-sensitivity, digital aeromagnetic survey that was flown over the U.S. Atlantic continental margin over a period of 15 months between 1974 and 1976. The 185,000 km of profile data have a relative accuracy approaching a few tenths of a nanotesla, which allowed compilation into maps at a scale of 1:250,000, with a contour interval of 2 nT. Automatic data processing using the Werner method allowed calculations of apparent depth to sources of the magnetic anomalies on all of the profiles, assuming a dike or interface as a source. Comparison of the computed depths to magnetic basement with multichannel seismic profiles across the survey area helped to reduce ambiguities in magnetic depth estimates and enabled interpolation of basement structures between seismic profiles. The resulting map showing depth to basement of the Atlantic continental margin is compatible with available multichannel seismic data, and we consider it a reasonable representation of the base of the sedimentary column.