Isotopic and Chemical Investigation of Chromatographic Effects During Melt-Mantle Interaction

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9628674 Nelson This project is to refine models of chemical reactions during melt migration through the mantle sing an extension of chromatographic theory. In addition to the chromatographic principles outlined by previous workers, we will include consideration of changing porosity, melt fraction and variable mineralogy as a function of extent and type of melt-mantle reaction. To test the model predictions, we propose to obtain a unique data set from thick alkalic basalt sequences. Initial implementation of this model suggests at lease three distinct chemical characteristics to search for its alkalic basalt sequences. In published data, previously, these trends have been ascribed to mantle metasomatism and/or presence of trace mantle phases such as zircon or rutile. Preliminary evaluation suggests that the chromatographic model may be an equally viable alternative hypothesis to explain certain alkalic basalt trends. The need for a more definitive test of the model motivates an analytical program to obtain isotopic and trace element flow-by-flow characterization of selected alkalic basalt vents on Hawaiian and Canary Islands.