Isotope sources of alkaline magmatism in the Clarion fracture zone, Pacific Ocean

The Pb-Sr-Nd isotope compositions of alkaline basalts from the Clarion Fracture Zone provide evidence for the lateral heterogeneity of the underyling mantle. The contributions of a variety of mantle reservoirs DM, EMI and HiMu were estimated using alkaline basalts from discrete portions of the fracture zone. The mantle source of basalts in its eastern sector was formed by the interaction of depleted mantle material and a mantle plume. The isotope signatures of basalts from the central sector indicate that the depleted mantle source like DM was mixed with approximately 0.15-1% pelagic sediments. Refs. 41, figs. 6