Ruohan Gao

The Hawaiian Islands are a chain of volcanoes formed as the Pacific plate moves northwestwards across a relatively stationary mantle plume. Hawaiian volcanoes commonly evolve through four stages that are characterized by different lava types, magma supply rates and inferred degrees of mantle melting: pre-shield stage, shield stage, post-shield stage, and a final rejuvenated stages.

 

Hawaiian lavas display significant chemical and isotopic variations. There is still no consensus as to whether these variations reflect intrinsic heterogeneity of the mantle plume, mixtures of the plume source with entrained mantle, or contamination by Pacific lithosphere. These debates are largely due to lack of constraints on the processes of magma mixing and evolution during transportation and the compositions of local Pacific lithosphere beneath the Hawaiian Islands.

 

Therefore, I approach these problems through examining the chemical and isotopic compositions of Pacific lower oceanic crust xenoliths and Hawaiian magma cumulates.