This project is to study four new eclogite xenolith localities from Yakutia, Siberia. It will provide a three-dimensional view of the craton edifice at various depths and distances from the craton edge. There has been much speculation and discussion over the petrogenesis of eclogite inclusions in kimberlite with some authors favoring high pressure igneous fractionation and others low pressure igneous fractionation. This study will compare and contrast pertinent chemical and isotopic signatures from the widely separated Kaapvaal and Siberian cratons. This multinational approach will include petrographic and mineral-chemical analyses of selected xenoliths. The study will include an exchange of scientific personnel between the United States and the Soviet Union. A representative suite will be chosen for further whole-rock, major-and trace-element analyses and O, Rb-Sr, Sm-Nd, U-Pb, and Re-Os isotopic analyses. Finally, the PI will use the results of this comprehensive study of the eclogite xenoliths of the SIberian craton, along with other data, to achieve a more complete and global picture of the formation of mantle eclogites and the structure and evolution of old cratons.
