BASEMENT GEOPHYSICAL INTERPRETATION OF THE NATIONAL PETROLEUM RESERVE ALASKA (NPRA), NORTHERN ALASKA

To produce maps of the thickness and inferred geophysical properties of the crust beneath the Ellesmerian rocks in NPRA we combine information from 1. total field aeromagnetic data, 2. terraced pseudogravity transform of magnetic data, 3. isostatic residual gravity, 4. basement residual gravity (based on geologic-stripping using seismic depth and velocity interpretations), 5. terraced basement gravity, 6. inferred Moho depth (from gravity inversion), 7. basement thickness (from both gravity and seismic interpretation), 8. Ellesmerian section thickness (from seismic interpretation), 9. basement depth (from seismic interpretation), 10. basement structure (interpreted from seismic data), and 11. limited well penetrations. Sialic crust characteristic of the Barrow Arch is thinned and modified to the south. Crustal physical properties indicate that dense and magnetic rocks make up a significant proportion of the crust in the southern part of NPRA.