In order to delineate magnetic lineaments, which may represent structural features, you can use several methods such as derivatives, source parameter imaging and Euler deconvolution. With some of them, you can also estimate the depth of these features. 

I crave your indulgence to start my submission from where Ashkan stopped or ended. The magnetic susceptibiliy between the two terrain will be different and as such delineation of the boundary will readily lend itself on either reduced to equator or reduced to pole magnetic intensity map. The sedimentary terrain should expectedly have low magnetic susceptibility compared to basement. This could be best done vis-a-vis the geological map of the area in question. The depths to magnetic source (basement) are determined from both Euler deconvolution and spectral analysis. Whilst Euler deconvolution gives all possible depths estimates together eith the associated shape of the body causing the anomalies due to non-uniqueness; the spectral analysis will reveal which of the depths estimates are acceptable and hence the shape of the body causing the anomaly. The structural framework is best carried out using toyal horizontal derivative or tilt derivative map derived from reduced aeromagnetic map (reducrd to equator or reduced to pole) especially in gray scale. Extract the lineaments from these maps and construct a stereonet showing the orientations of the extracted lineaments. With the orientations you could deduce the orogeny of the area. By overlain the extracted lineaments on both geologic map of the area and the reduced map, geologically tealistic structural interpretations can be carried out. You could also use upward continuation process to infer some structures especially faults. Moreso, faults can be mapped on the lineaments overlain on geological map.

to add to the submission of Adabanija, also performing ANALYTIC SIGNAL on the residual map would orientate the anomalies along the boundaries to appear directly on their sources.