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Window-based Euler deconvolution is commonly applied to magnetic and sometimes to gravity interpretation problems. For the deconvolution to be geologically meaningful, care must be taken to choose parameters properly. The following proposed process design rules are based partly on mathematical analysis and partly on experience. 1. The interpretation problem must be expressible in terms of simple structures with integer Structural Index (SI) and appropriate to the expected geology and geophysical source. 2. The field must be sampled adequately, with no significant aliasing. 3. The grid interval must fit the data and the problem, neither meaninglessly overgridded nor so sparsely gridded as to misrepresent relevant detail. 4. The required gradient data (measured or calculated) must be valid,with sufficiently low noise, adequate representation of necessary wavelengths and no edge-related ringing. 5. The deconvolution window size must be at least twice the original data spacing (line spacing or observed grid spacing) and more than half the desired depth of investigation. 6. The ubiquitous sprays of spurious solutions must be reduced or eliminated by judicious use of clustering and reliability criteria, or else recognized and ignored during interpretation. 7. The process should be carried out using Cartesian coordinates if the software is a Cartesian implementation of the Euler deconvolution algorithm (most accessible implementations are Cartesian). If these rules are not adhered to, the process is likely to yield grossly misleading results. An example from southern Africa demonstrates the effects of poor parameter choices.

The recently released gravity potential field development derived from the Gravity Recovery and Climate Experiment satellite allows an unprecedented opportunity to use the gravity field to make global comparisons of structures of geological interest. The spatial resolution of the gravity field is sufficiently good to map large-scale or intracratonic and cratonic basins, as the areal extent of these basins is 0.5 x 10 6 km 2 and greater. We present the gravity anomaly, Bouguer, geoid and terrain corrected geoid fields for a selection of nine large-scale basins and show that the satellite-derived field can be used to successfully identify distinctive structures of these basins, e.g., extinct rifts underlying the basins and generally the isostatic state. The studied basins are the Eastern Barents Sea, West Siberian, Tarim, Congo, Michigan, Amazon, Solimoes, Parnaiba and Parana basins. We complete the mapping of the gravity field with a description of the basins in terms of areal extension and depth, sedimentary age and presence and age of volcanism. Interpretation of the satellite gravity anomalies and considerations regarding the crustal thickness as known from seismic investigations, allows us to conclude that for the greater part of the basins there is evidence for high-density material in the lower crust and/or upper mantle. This density anomaly is, at least partly, compensating for the low-density sedimentary infill instead of the crustal thinning mechanism. For our selection of basins, crustal thickness variations and Moho topography cannot be considered as mechanisms of compensation of the sedimentary loading, which is a clear difference to well-defined rift basins.

We discuss the correlation between the depth extent of magnetic sources, the Curie temperature depth and crustal structures on the mid-Norwegian margin. Spectral methods can be used to estimate the depth extent of magnetic sources, even if the bottom is located in the lower crust, however, only with limited resolution. The bottom of the magnetic surfaces is often regarded to represent the depth to the Curie isotherm. However, comparison with a 3D model based on the interpretation of potential field and seismic reflection data and thermal modelling shows that the depth extent of the magnetic sources is merely controlled by the overall geometry of the crystalline crust and not the temperature distribution. The observed changes in the magnetic field between the inner and outer part of the mid-Norwegian margin appears not to reflect, as previously assumed, the depth to the Curie temperature but the geometry of the basement and lower crust. Our 3D model of the mid-Norwegian margin reveals a basement configuration that involves a basement with different petrophysical properties, which can be connected with lithological basement units of onshore Norway.

This study investigates the utility of the potential fields (gravity and magnetics) in volcanic settings as observed on the More margin. Synthetic models are used to investigate the effect of volcanics on the gravity and magnetic fields. The focus is on detecting sub-basaltic basement structures. The methods applied to the models are Euler deconvolution on magnetic data, gravity gradients and integrated 3D gravity and magnetic forward modelling. The same methods are used on the More margin and the results compared to the synthetic models. The Euler deconvolution on the magnetic signal does provide limited depth solutions in the volcanic environment and the use of different observation levels does not enhance the results. Forward gravity and magnetic models provide a valuable tool to estimate both the basalt and sub-basaltic sedimentary thickness but are limited by the ambiguity inherent in potential field methods. The use of gravity gradients significantly decreases the available model solutions and provides boundary detection even in sub-basaltic settings.