f Subtle traps in extensional terranes

In mature basins like the North Sea Basin, exploration efforts are increasingly centered towards the search for subtle traps, including structural as well as stratigraphic traps. Subtle traps obviously develop in a wide range of geological settings (Halbouty 1980, 1982), but due to the extensional nature of the North Sea Basin this paper will focus on subtle traps in extensional terranes (Fig. 1).