It is widely known that, in order to model tectonic processes accurately, 3D approaches are required. However, due to the greater numerical challenges and much enhanced costs, most commercially available software packages only offer two-dimensional or “pseudo three-dimensional” (2.5-D) applications to simplify the underlying mathematics. In the 2.5-D approach, the third dimension is generally created by a mere orthogonal projection of a single section in two directions at a certain distance from its original position. Yet, despite creating a 3D space, lateral variations in the subsurface are ignored and the resulting model often remains an oversimplification that often does not represent natural observations. A particular problem is given in sedimentary basins containing salt. The fluidlike behavior of salt over geological times requires true 3D models to allow for in- and out-of section salt flow and to preserve both the salt mass and its volume. None of this can be achieved in 2D or 2.5-D, respectively. Evaluation of evolutionary models derived from 2D restoration must therefore consider the associated geometric simplifications.

There are many publications describing a thermal gravity anomaly associated with young oceanic crust at mid-ocean ridges. This anomaly is due to lateral density changes in the lithosphere resulting from temperature variations within the asthenosphere. The amplitude of this thermal Bouguer gravity anomaly can be as large as-300 milliGals at the location where new oceanic crust is formed and is easily observed in the gravity data. A detailed gravity model extending from the West African Craton across the Mid-Atlantic Ridge clearly shows this thermal gravity anomaly and its lateral extent. The model also clearly shows that there is no evidence of a thermal gravity anomaly at the rifted continental margin of the Kwanza basin, offshore Angola.