Magsat data were used in many studies to investigate the regional extent and character of major continental and oceanic tectonic features. A fundamental problem in this regard is the apparent lack of a long-wavelength continent-ocean anomaly in many places, commonly explained in theoretical models as being caused by the spherical harmonic separation of the main field components. This expression of the continent-ocean boundary in Magsat data, or lack thereof, was the focus of several investigations.
Hinze et al. [1991] inverted 
reduced-to-pole Magsat anomalies to determine effective susceptibility
contrasts between thick continental crust and thin oceanic crust. By
examining mean susceptibility contrasts between oceanic and continental
regions, they hoped to determine if a simple binary distribution of
regional magnetization existed; i.e., if the integrated magnetization
of continental lithosphere is always greater than oceanic lithosphere.
If so, the ocean-continent anomaly could be masked by the main field.
The study found that, overall, the oceans have a wider range of
susceptibility contrasts (with a significantly negative mean) compared
to the continents. This supports the argument that harmonics generated
by the ocean-continent anomaly overlap with the main field harmonics.
Moreover, the more variable susceptibility of the oceanic crust can
explain in part the global variability in magnetic contrasts across the
continent-ocean transition seen in the Magsat anomaly field.
Bradley and Frey [1991] concluded that the positive contrast between Greenland and the Labrador Sea arises principally from the greater thickness of the continent rather than its greater susceptibility, indicating that anomalies over passive continent-ocean margins are edge-effects. Toft and Arkani-Hamed [1993] used forward models to derive an estimate of the magnetization contrast between the Precambrian microcontinent of Rockall Plateau and the induced magnetization of the surrounding North Atlantic oceanic crust. Their estimate, which they argued should represent an upper bound on contrasts at passive continental margins, is substantially lower than estimates from the margins of the Labrador Sea [ Bradley and Frey, 1991] and the range of vertically-integrated magnetization contrast across ocean-continent boundaries that was obtained in a global survey by Counil et al. [1991]. The variations in these estimates partially reflect the different methods used to derive them, but they also may reflect the variation in magnetic contrasts across ocean-continent transitions, which is indicative of their rifting styles and histories.
Major magnetic contrasts of South America and Africa were studied by Ravat et al. [1992], who found a remarkable correspondence of magnetic anomalies across the reconstructed rifted continental margins and a negative relationship between anomaly amplitude and Mesozoic hotspot tectonism in the continent. This study and a study of the satellite anomaly pattern over Europe by Ravat et al. [1993] indicate that the intruded lower crust at continental rifts is dominated by weakly magnetized to nonmagnetic titanomagnetite. Ghidella et al. [1991] correlated Magsat anomalies with aeromagnetic data in West Antarctica and used constraints from both to infer the lateral extent and probable thickness of the magmatic arc complex of the Antarctic Peninsula. They also modeled a prominent ocean-continent boundary anomaly in the Weddell Sea as an extension of the seaward-dipping seismic reflector sequences observed offshore Dronning Maud Land, Antarctica.
These studies, while not definitive in their conclusions because of the accuracy and resolution of the Magsat data, do offer valuable insights into the processes which create and modify the crust, particularly the lower crust, where the sources of the anomalies are frequently presumed to reside. The satellite-altitude magnetic anomaly field can contribute to mapping deeply buried continental rifts, while the persistence of magnetic contrasts across the South America/Africa margins, inherited from the Gondwana configuration, indicates little alteration of the lower crust since break-up. The subject of magnetic contrasts at (passive) continental margins remains controversial but should yield to more systematic efforts to understand if and how long-wavelength continent-ocean anomalies are masked by overlapping core harmonics. Proper resolution of this problem will require acquisition of higher accuracy and higher resolution satellite anomaly fields. The magnetic structure of the continental margins, reflecting variations in magma supply and composition, is a valuable constraint on models of rifting and hotspot versus passive convection models of volcanism at rifts. The unique capability of satellite magnetic anomaly data to detect lower crustal magnetization and its sensitivity to lateral thermal gradients within the lithosphere argue in favor of acquisition and interpretation of higher accuracy and higher resolution satellite magnetic field data. As an indication of the popularity of this view, Taylor et al. [1992] reported on the results of a survey of industry geopotential field specialists involved in resource analysis; the respondents find Magsat data useful in their evaluations, and have expressed interest in future lower altitude magnetic field missions.