Jane Barling

Mantle heterogeneity is identified by both geophysicists and geochemists. Their observations are complementary but not well integrated. Geophysicists measure the travel times of seismic waves through the earth which enables them to identify mantle regions through which seismic waves travel faster or slower than average. In contrast geochemists document the chemical heterogeneity of the mantle by analysing magmas erupted from volcanoes. Using radiogenic isotopes such as Nd, Sr & Pb has enabled them to characterise the extremes of compositional heterogenety in the mantle, these extremes are called mantle components. In the last 10 years the first steps have been taken towards mapping of these components onto the geophysically identified heterogeneities. The application of non-traditional stable isotopes to mantle geochemistry is also very recent but has already proved useful in constraining subduction zone processes. The extent to which fractionation of non-traditional stable isotopes at the surface and during subduction is detectable in the mantle materials and the degree to which high temperature mantle processes can fractionate them, is as yet unknown.

My focus is on investigating Ni and Mo isotope variations in OIB in order to contribute to our understanding of the processes involved in developing large-scale mantle source heterogenity and using this information to further enhance the linking of geochemical and geophysical heterogeneities. The simple binary mixing systematics seen in radiogenic isotopes in Heard Island lavas makes this OIB suite particularly useful for interpreting non-traditional stable isotope systematics.