Figure 6. Correlation of free-air anomaly and the discriminant D1 along the MAR axis in the study area. D1 computed from a sample of 2964 chilled glass analyses from the GEOKhI data base, including Volcanic Deep Sea Glass Data Base, W. G. Melson et al., Smithsonian Institution, Department of Mineral Sciences. 2000; Ridge Petrological Data Base, Lamont Doherty Earth Observatory, 2000, new and published data. Distributions of plume and spreading basalt associations shown by different symbols.