Structural and Thermal Control on the Depth to Bottom of Magnetic Sources – A Case Study from the Mid – Norwegian Margin

We discuss the correlation between the depth extent of magnetic sources, the Curie temperature depth and crustal structures on the mid-Norwegian margin. Our results show that classical spectral methods can be used to estimate the depth extent of magnetic sources, even if the bottom is located in the lower crust, and only with limited resolution since large analyzing windows (> 200 km) have to be used to resolve the deep sources. The depth extent of the magnetic sources is controlled by the crustal<br>geometry and not the temperature distribution in the crust. Comparison with thermal modeling allows us to argue that the observed magnetic field on the mid-Norwegian margin does not reflect the Curie temperature depth as previously assumed, but the geometry of the basement and lower crust.