4 Billion Years of Maturation of the Continental Crust

Key findings:

The key finding from the project is that the continental crust is heterogenous in it's Mg isotope composition, and that the absolute composition of any given rock apparently depends on the age of the rock.

This must relate to water-rock interaction (weathering) influencing the composition of the continental crust at the Earth's surface (Tipper et al in Prep).

A second key finding is that the Mg isotope composition of the mantle is constant (Bourdon et al 2010).

However, individual minerals from the mantle show a wide variation in Mg isotope composition, reflecting equilibration amongst individual phases (Stracke et al in prep)

Another key finding is that Mg and Li isotopes co-vary in the Mackenzie River basin, and a model of clay formation has been developed to explain this (Tipper et al 2012).