Geochemical provincialism in the Iceland plume

The spatial trends that we observe on Iceland are similar to those seen on Hawaii between the Loa and Kea volcanic chains, which also show shifts in mean Pb isotopic composition and binary mixing array. However, on Iceland we are able to see that, rather than representing dichotomous compositional domains on either side of the island, the change in mean composition and mixing array occurs continuously. Geochemical structure only shows segmentation on the scale of a neovolcanic zone. Discrete arrays in isotopic space on the scale of volcanic systems may develop in response to mixing in the melt transport and storage system and require neither the shallow nor the deep mantle to exhibit sharp (<100km) lateral contrasts in composition.