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An interpretation is presented of a 219 km regional profile which traverses the eastern Columbia River Plateau in Washington State. Aeromagnetic, magnetotelluric (MT), and gravity data were first interpreted separately. All three data sets then were satisfied by a single geologic model. The objective of this case study is to illustrate the individual contributions derived from these three geophysical data sets to a final integrated interpretation. The aeromagnetic interpretation has produced regional structural information and data from which rock compositions can be inferred. The MT interpretation shows that the basalt/sediment interface can be determined, and thus a relative sediment thickness can be inferred. The gravity interpretation is dependent upon an additional method to determine either the basalt or basement horizon. In order for the gravity interpretation to approximate depth to basement or sedimentary thickness, the base of the basalt must be determined from another scientific method. From comparison of the regional structural results of the three geophysical techniques we conclude that aeromagnetic or MT data can be used to determine major structural trends. Reasonable rock compositions are also determined from the combined data sets. The interpreter must be aware of the different rock properties measured by each tool when performing an integrated interpretation; comparisons between the various techniques must be based upon similar assumptions. We recommend that detailed, integrated models be included for a thorough evaluation of any basalt‐covered area. The analysis of rock composition and regional structural information thus derived provides a sound basis for a regional tectonic interpretation and subsequent prospect evaluation.

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A new quantitative magnetic interpretation of the northern Gulf basin maps magnetic basement structure in greater detail over a wider area than is known to be available elsewhere. This interpretation is based on magnetic depth estimates derived from the analysis of over 100,000 line miles of aeromagnetic data and 25,000 line miles of marine magnetic data. Depth estimates have been correlated with published seismic reflection and refraction data, well data, and to a lesser extent, published gravity data. The integration of various independent data sets thereby permits a more confident separation of, and mapping of, magnetic anomaly sources as either basement related or intrasedimentary. Results of the quantitative interpretation demonstrate that qualitative gravity/magnetic interpretations must be used with care. There are strong correlations between many of the geologic trends documented onshore Texas and Louisiana and the interpreted magnetic basement features, both onshore and offshore. Most basement features are either subparallel or subnormal to the coast. NE structures and fault trends are dominant offshore Texas and form important crosstrends offshore Louisiana. At lease three named NW-SE crosstrends or transfer zones continue from onshore Texas into the Texas offshore. There are good correlation between interpreted basement block boundaries and major Tertiary fault zones such as the Corsair, Wanda, South Cameron, and South Timbalier-Ship Shoal. Magnetic basement indicates that presence of more that twenty subbasins with sufficient sediments to be of exploration interest. Offshore, the basement depths range from about 30,000 feet (9.1 km) over features such as at the Perdidio Uplift to 70,000 feet (over 21 km) in some of the Tertiary deeps.

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