Other discrimination diagrams using Ti-Zr-Y-Nb variations

A number of other tectono-magmadc discrimination diagrams have been proposed based upon Ti-Zr—Y variations and these are discussed below. In addition the HPS element Nb is used, although diagrams which introduce Nb should be used with care. Nb concentrations cannot be accurately determined by XRF below about 10 ppm and precise analyses must be made by INAA. 

Within-plate alkali basalts plot in field A within-plate riioleiites plot in fields All and C. E-type MORB plots in field B whilst N-type MORB plots in field D. Volcanic-arc basalts also plot in fields C and D. The several areas of overlap mean that only within-plate alkali basalts and E-type MORB can be identified without ambiguity, 

---