Geomagnetic variation studies in the southern Appalachians: preliminary results

摘要: Magnetic field variations have been recorded at 12 stations located on a traverse across the Blue Ridge and the Piedmont provinces of the southern Appalachian system in Georgia. The records were Fourier analyzed, and the transfer functions, relating the anomalous vertical magnetic field variations to the horizontal field, were obtained for different periods ranging between 16 and 4000 s. The transfer functions for the southeasternmost stations seem to be affected by the coast effect and possibly by the Coastal Plain sediment. In the northwestern part of the survey, the direction of the transfer functions was away from the coast. This suggests the presence of a strong conductor in the lower crust or the upper mantle beneath the Blue Ridge and extending farther toward the northwest.