Figure 8. Compositional changes in magmas produced by the Hawaiian hotspot through time. The shaded field shows the range of published 87Sr/86Sr of tholeiitic basalts vs. age and distance along the Hawaiian-Emperor chain. Note that data from Detroit seamount are significantly less radiogenic than at younger volcanoes. The crossed circles connected by the thick dotted line shows the trend in age difference between seamounts and the underlying ocean crust (from Keller et al., 2000).