The general aim of this project is to understand planetary constitution and evolution. Throughout their history, planets are extensively processed chemically and each is uniquely differentiated. Laboratory experiments are used to investigate the physical chemistry of those liquid and solid-state processes thought to be responsible for particular processing effects. Pressure is an important dimension in experimental studies of planetary interiors. The major expression of planetary differentiation is the separation of core and mantle. The means by which the core and mantle continue to interact chemically after their separation depends, among other things, on the solubility of nonmetals in the liquid outer core, and the physical chemistry of the core-mantle interface. This project will make use of equipment developed in team mode at the Advanced Light Source/Lawrence Berkeley Lab, that will unable the investigators to make significant progress in determining nonmetal solubility in liquid Fe at a very high pressure.
The partitioning of trace elements among inner core, outer core, and mantle is a useful tracer of the planetary evolutionary process. Pressure variations of trace element partitioning are often obscure because pressure is not usually an independent variable in an equilibrium system. One of the goals of the project will be to exploit a favorable opportunity in the physical chemistry of the model system Fe-FeS to dispel some of this obscurity, initially for Mo and W, an element pair with particularly irksome and unexplained contrasts in their behavior including their apparent pressure variations.
The prevalence of solutions among minerals of planetary interiors makes the rules of solution behavior a subject of importance. Another task to be undertaken will be to explore the effects of pressure on garnet solid solutions, as garnets are important repositories of fusible components that contribute to basalt upon deep partial melting in the Earth's mantle - a most important activity in planetary differentiation.
