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

University Of Arizona, Tucson AZ

Investigators

Abstract

EAR-0001945 T. Gasparik, M. J. Drake, J. B. Parise: Collaborative Research of the Origin of Inclusions in Diamonds From the Deep Mantle In this CSEDI collaborative research project, we plan to continue our experimental investigation of the origin of inclusions in diamonds from the deep mantle using the minor and trace element contents of the inclusions. Observed element contents will be matched in high-pressure experiments on phase relations and element partitioning in those assemblages which include phases found as inclusions in diamonds. We will complete our ongoing studies of the origin of inclusions with CaSiO3 and (Mg,Fe)O compositions, and then extend the investigation to the origin of majoritic garnet inclusions. The minor and trace element contents to be matched by experiments are available for all three kinds of inclusions. Partitioning of these elements among phases in various assemblages, which include analogues of the selected inclusions and other phases observed as inclusions, is determined over a range of experimental pressures, temperatures and compositions, until a close match is found between the minor and trace element contents of the inclusions and of the analogue phases. The compositions of the coexisting phases then provide information about the original assemblage, from which the inclusion came, and thus constrain the mineral and chemical composition of the source region and the P-T conditions of origin.