The tectonic histories of several continental regions were elucidated in greater detail as a result of the interpretation of higher resolution magnetic anomaly data sets in conjunction with gravity, seismic, and geologic data. These data sets were used to characterize the subsurface in order to develop a more accurate picture of the magmatic and deformational evolution of areas now hidden beneath sedimentary cover. Blakely and Jachens [1991] delineated the extension of the northern Nevada Rift into southern Nevada and mapped the thickness of sedimentary cover from a joint interpretation of gravity and magnetic data. They inferred that the mid-Miocene northern Nevada rift enhanced the strength of the crust, as demonstrated by its apparent immunity to later deformation that formed most of the sedimentary basins.
Holbrook et al. [1994] and Lizarralde et al. [1994] combined seismic reflection and refraction data with magnetic and gravity anomaly data to investigate the structure and evolution of the U.S. Atlantic continental margin. Holbrook et al. [1994] interpreted magnetic susceptibilities, inferred from modeling the East Coast and Brunswick magnetic anomalies using seismic constraints on crustal thickness, to indicate highly mafic material in the continent-ocean transition zone emplaced during rifting. An abrupt change in seismic and magnetic properties occurs at the landward edge of the 80-km wide transition zone, which results in the prominent Brunswick magnetic anomaly; a similar contrast in crustal properties is observed offshore Georgia, where an abrupt change to more mafic crust occurs seaward of this anomaly [ Lizarralde et al., 1994]. The documentation of a thick volcanic sequence in the ocean-continent transition zone, equivalent in volume to large igneous provinces associated with plume heads but for which no evidence of a plume origin exists, implies that enhanced convection during rifting is responsible for this massive igneous event [ Holbrook et al., 1994].
Finn [1994] produced a revised basement map of northeast Japan based on interpretation of a recently acquired high-resolution aeromagnetic data set, guided by drill hole, seismic, and gravity data. She mapped the extent of a buried and previously unrecognized Early Cretaceous batholith and inferred a large amount of tectonic erosion or thrusting at the margin in order to explain the lack of Cretaceous forearc deposits implied by the position of the paleo-magmatic arc. In a more contemporary setting, Blankenship et al. [1993] mapped an active volcano within the West Antarctic rift system beneath the West Antarctic Ice Sheet with combined airborne ice-penetrating radar, magnetic, gravity, and altimetry data. Their interpretations, that volcanism is currently active and that the lithosphere participates in controlling ice sheet stability, will have important implications for the neotectonic and glacial history of West Antarctica.