Abstract
Magnetic anomaly data, acquired by NASA's MAGSAT satellite, have been processed, analyzed, and interpreted in terms of causative crustal sources (major structures, tectonic development, geologic provinces, crustal composition and magnetic properties) in the central U.S. midcontinent. An optimum data set was developed by cleaning, correcting, and editing, and then reduced to a 1° × 1° latitude/longitude grid at a common altitude of 400 km, then wavelength filtered and reduced to the magnetic pole. The resulting satellite anomalies have a magnitude range up to ±15 nT in the region. The relationship between these long-wavelength anomalies and crustal sources is investigated. A magnetic high over Kentucky/Tennessee is associated with more mafic and thicker lower crust, and a high over Texas/Oklahoma and trending northeast through Missouri may be due to a geologic province and anomalously-magnetic lower crust. A magnetic low over the Mississippi Embayment/aulacogen can be explained by crustal thinning and less-magnetic crust, and one over Georgia by less-magnetic lower crust. The magnetic anomaly gradient pattern generally follows and reflects the southern ancient rifted continental margin of the North American craton, and there is a lack of apparent magnetic expression of the Central North American Rift system (Midcontinent Geophysical Anomaly).
Published Version
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