This is a proposal to study the petrogenesis of mantle eclogites and the dynamics of their emplacement within the framework of the evolution of ancient sub-cratonic mantle and the early evolution of the Earth. In this proposed research, work concerning two localities will continue, and study extended to two additional kimberlite localities in Yakutia, Siberia. These occurrences are postulated to have sampled a wide range of depths in the mantle and are situated at varying distances from the craton edge. The proposed study would continue the NSF-sponsored US/Russia Cooperative Research Program and agreement between Prof. L.A. Taylor of the University of Tennessee and Academician N.V. Sobolev of the Siberian Branch of the Russian Academy of Sciences. This multi-national approach will include petrographic and mineral-chemical analyses of selected xenoliths from the aforementioned kimberlite pipes in Siberia. This study will include an exchange of scientific personnel between the United States and Russia. O, Rb-Sr, Sm-Nd, and Re-Os analyses will be performed on mineral separates in diamonds to determine the involvement of mantle and crustal reservoirs in eclogite genesis. A new and exciting direction involves a study of major- and trace- element chemistry of eclogite minerals found in several of the Yakutian diamonds. The results will be used to achieve a more complete and global picture of the formation of mantle eclogites, the structure and evolution of old cratons, and the differentiation of the early Earth.
