Figure 2. (a) Zr/117–Nb/16–Th diagram showing the basaltic lavas with respect to the fields for within-plate basalt (WPB), volcanic-arc basalt (VAB), normal (N) MORB and enriched (E) MORB (after Wood, 1980). (b). Zr/Y v. Zr discriminant diagram for the basaltic lavas within the Tethyan suture zone in western Turkey. The fields of within-plate basalt (WPB), mid-ocean ridge basalt (MORB) and island arc basalt (IAB) are from Pearce & Norry (1979).