Figure F10. A. Variations in ²⁰⁶Pb/²⁰⁴Pb along the Southeast Indian Ridge between 115°E and 140°E. The present position of the isotope boundary between Indian- and Pacific-type mid-ocean-ridge basalt provinces is located at ~126°E. These data are taken from Klein et al. (1988), Pyle et al. (1992), and Pyle et al. (1995). AAD = Australian Antarctic Discordance. B. Variations of Zr/Ba vs. ²⁰⁶Pb/²⁰⁴Pb showing the data distribution for determining Indian- and Pacific-type mantle provinces. These data are taken from Klein et al. (1988), Pyle et al. (1992), Pyle (1994), Pyle et al. (1995), and D.G. Pyle and D.M. Christie (unpubl. data).