Regional gravity and magnetic anomalies in the eastern Snake River Plain, Idaho

摘要: Over the eastern Snake River Plain, Bouguer gravity anomaly and magnetic intensity are, in general, high. In detail, both anomalies are a complex of highs lows, contrast to simpler over western Plain. The broad high associated with Plain cannot be produced by dense mass at shallow depth under plain, but must either deep feature plain or broader, shallower extending well beyond plain. could thinning crust 4.5 7 kilometers. data suggest that Cenozoic rocks underlain have density magnetization similar pre-Cenozoic north south do not rifting upper such as is inferred for approximate isostatic equilibrium adjoining regions thus contrasts areas where basin-and-range topography equilibrium. localmore » on probably variations thickness rocks, wavelength about twice structural features expression does extend far onto plain.Magnetic volcanic rocks.« less