Chapter 18: A crust/mantle structural framework of the conterminous United States based on gravity and magnetic trends

Crust and Lithospheric Structure - Global Crustal Structure

“…Short-wavelength (<250 km) gravity anomalies are usually correlated with crustal structures, while long-wavelength (< 1000 km) gravity anomalies are correlated with lateral variations of mantle densities. Kane and Godson (1989) demonstrated that longwavelength gravity highs are correlated with high mantle seismic velocities and gravity lows with low mantle velocities. Kaban et al (2003) showed that upper mantle density variations contribute long-wavelength gravity anomalies ranging from À250 mGal to þ150 mGal.…”

Laccolith complexes of southeastern Utah: Time of emplacement and tectonic setting — Workshop proceedings

“…The plateau is situated on the axial crest and west flank of the regional elevation anomaly of the Western United States (the Cordilleran "geanticline" of Hunt, 1956). This long-wavelength topographic feature corresponds very closely to the 1,000-km low-pass Bouguer gravity anomaly depicted on the map of figure 6 (modified from others, 1982, andGodson, 1989; a color plate accompanying the latter paper also displays a map of the elevation anomaly). This map shows the deep low that remains after removal from the Bouguer data set of all spectral components with wavelengths less than 1,000 km.…”

“…Possible origins of the long-wavelength Cordilleran anomaly, in consideration of gravity and seismic data, have been discussed by Kane and Godson ( 1989). In their view the Bouguer gravity low cannot be accounted for by crustal variations alone and must involve a buoyant upper mantle (75 percent of the buoyancy residing in the upper 160 km) in order to maintain a condition of regional isostatic equilibrium as implied by near-zero average (long-wavelength) free-air anomalies (as shown by Simpson and others, 1987, for instance).…”

“…These included maps of the Bouguer and isostatic gravity anomalies, aeromagnetic total-intensity anomaly, aeromagnetic anomaly reduced to pole, and selected derivatives of these parameters. Smaller-scale maps that were used include (1) wavelength filtered gravity maps of Hildenbrand and others (1982) and Kane and Godson (1989); (2) a wavelength terrain map of Kane and Godson (1989); and (3) basement and tectonic compilations of Bayley and Muehlberger (1968), Bayer (1983), Muehlberger (1992), and Reed (1993). Reed's (1993) basement compilation is also overprinted on isostatic residual gravity and magnetic anomaly maps of the conterminous United States (Jachens and others, 1993, and Committee for the Magnetic Anomaly Map of North America, 1993, respectively).…”

Analysis of gravity and magnetic fields in the Canadian Shield using standard and wavelet-based methods

“…Magnetization is principally a function of magnetic mineral content and is affected by metamorphism and alteration. It is not directly related to lithology but we can correlate its patterns with known geology [Kane and Godson, 1989]. This is clearly seen by comparing analysis [Isnard et al, 1998].…”