9614178 Sparks Komatiite lavas, with extremely high eruption temperature provide unique information about the Archean mantle. Simple models of the major element compositions of Archean komatiites indicate melting at very high temperatures and pressures (potential temperatures greater than 1800C and depths of at least 250 km), but the dynamics of upwelling, melting and melt extraction in these areas of the mantle are not understood. The PI proposes to integrate a numerical model of mantle convection and melting with parameterizations of melt compositions from high pressure melting experiments. These models will be used to systematically explore the effects of poorly constrained properties of and conditions in the Archean mantle (temperature, composition, viscosity, melt migration permeability, lithospheric thickness) on the major and trace element composition of the melts that are produced. The compositions of ultramafics and other Archean rocks will be used to constrain the hypotheses and assumptions of the models. A flexible and efficient model that can determine the dependencies and interactions between the fluid dynamics and chemistry of mantle melting will provide both insight into the dynamics of the Archean mantle and guidance in setting the priorities of future experimental programs.
