CSEDI Collaborative Research: of the Origin of Inclusions in Diamonds from the Deep Mantle

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EAR-0001945T. Gasparik, M. J. Drake, J. B. Parise: Collaborative Research of theOrigin of Inclusions in Diamonds From the Deep MantleIn this CSEDI collaborative research project, we plan to continue ourexperimental investigation of the origin of inclusions in diamonds from thedeep mantle using the minor and trace element contents of the inclusions.Observed element contents will be matched in high-pressure experiments onphase relations and element partitioning in those assemblages which includephases found as inclusions in diamonds. We will complete our ongoingstudies of the origin of inclusions with CaSiO3 and (Mg,Fe)O compositions,and then extend the investigation to the origin of majoritic garnetinclusions. The minor and trace element contents to be matched byexperiments are available for all three kinds of inclusions. Partitioningof these elements among phases in various assemblages, which includeanalogues of the selected inclusions and other phases observed asinclusions, is determined over a range of experimental pressures,temperatures and compositions, until a close match is found between theminor and trace element contents of the inclusions and of the analoguephases. The compositions of the coexisting phases then provide informationabout the original assemblage, from which the inclusion came, and thusconstrain the mineral and chemical composition of the source region and theP-T conditions of origin.