Estimation of the Depth to the Magnetic Basement in Europe Using the Spectral Method

Despite several geological and geophysical studies that have focused on the estimation of the geometry of the sedimentary basins, the seismic documentation of sediment thickness is inadequately constrained due to the sparse spatial resolution of the expensive seismic and borehole measurements. To provide a new complementary insight into the morphology of the crystalline basement, I have re-examined the radially averaged power spectrum of magnetic anomalies for mapping depth to magnetic basement (DMB). DMB is a proxy of the non-magnetized sediment cover thickness over the magnetized crystalline basement. Synthetic models suggest that the accuracy of the method is not significantly influenced by the unknown magnetic fractal parameter and depth to the bottom of the magnetic slab. The windowing and window size effect on the estimated DMB can be substantial. Our synthetic tests suggest that the uncertainty of the calculated DMB increases with depth if the chosen window size is less than eight times the real DMB. I applied this method to the European, Greenland and North Atlantic regions because of the availability of seismically constrained sediment thickness or depth to the seismic basement (DSB), which allows comparison between DMB and DSB. The estimation of DMB was done by assuming a constant fractal parameter of three within a sliding window and with a variable size from 100 × 100 km in 10 km steps to a maximum size of 200 × 200 km until the estimated DMB is less than one eighth times of the window size. Comparison of DMB with DSB indicates a striking long-wavelength correlation along major sedimentary basins, while discrepancies may indicate limitations in the estimation methods for DMB and DSB.