Abstract

The chemistry of basaltic melts contains information about the nature of their mantle source regions, in particular their composition, temperature and flow rate. Such information places key constraints upon our understanding of mantle convection. However, the models used to link basalt compositions to mantle properties contain a number of key assumptions regarding the lengthscales of mantle heterogeneity, and the role of magmatic processes as a filter for the mantle signal. Melt inclusions which are trapped within olivines growing deep in the magmatic system provide a record of the evolution of melt compositions and can be used to understand the role of this magmatic filter. New results from Iceland indicate that the mantle is extremely heterogeneous on lengthscales of

References:

Meyzen, C. et al., Isotopic portrayal of the Earth’s upper mantle flow field, Nature, 447, 1069-1074, 2007.

Maclennan, J., Lead isotope variability in olivine-hosted melt inclusions from Iceland, Geochimica et Cosmochimica Acta, 72, 4159-4176, 2008.

Maclennan, J., Concurrent mixing and cooling of melts under Iceland, Journal of Petrology, doi:10.1093/petrology/egn052, 2008.