Characterization of the Effects of Diffusive Reequilibration on the Compositions of Olivine-Hosted Melt Inclusions

Woods Hole Oceanographic Institution, Woods Hole MA

Investigators

Abstract

Gaetani EAR-0087525 The objectives of this project are (1) to identify elements whose concentrations are conserved once incorporated into an olivine-hosted melt inclusion, and (2) to quantify the amount of post-entrapment crystallization that is typically "erased" by diffusive reequilibration of Fe and Mg in the host olivine. These goals will be achieved by (1) determining experimentally the diffusivities of select minor elements (Ca, Al, Ti) in magnesian olivine, (2) determining experimentally the mineral-melt partitioning systematics of elements present in olivine as minor constituents for which there is currently very little data (Al, Ti), and (3) combining the experimental results with a secondary ion mass spectrometry study of the olivine adjacent to melt inclusions to identify and characterize concentration gradients in slow diffusing minor or trace elements that result from post-entrapment crystallization. The data collected over the course of this experimental and analytical study will provide a better understanding of the effects of post-entrapment crystallization and diffusive reequilibration on the major element compositions of olivine-hosted melt inclusions, increasing their value as sources of geochemical information about the processes of melt generation and extraction in the upper mantle of the Earth.