Simultaneous Inversion of Vector and Total Field Aeromagnetic Data Using Bayesian Inference: A Case Study from the Cobb Offset of the Juan de Fuca Ridge

摘要

The application of the measurement of all three components (north, east, and downward) of the Earth's magnetic field is introduced. In addition, numerical inversion techniques are presented which facilitate the interpretation of the data over an active oceanic ridge, the Cobb Offset of the Juan de Fuca Spreading Center. High resolution bathymetry, obtained using a state-of-the-art mapping system, SEABEAM, and single channel seismic data, numerically provide geologic constraints in the inversion process. The research represents the first application of vector magnetic observations for a geophysical investigation. The Juan de Fuca Spreading Ridge, located off the coast of the states of Washington and Oregon, demonstrates tectonic motion not fully explained by rigid plate theory. In particular, the Cobb Offset, a horizontal displacement between two opposing ridge segments, is shown to be the product of opposing along-strike ridge propagation rather than transform faulting. Estimates of the apparent magnetization and the geometry of the magnetic source material (i.e., basalt) are also presented.