This is a petrologic, geochemical and isotopic study of eclogite xenoliths in kimberlite pipes of the Roberts Victor mine in South Africa, and from the Colorado-Wyoming state line district in the U. S. Standard petrologic methods will be used, followed by Sm- Nd, Rb-Sr, U-Pb and Lu-Hf isotope studies. In addition Concentration of rare-earth elements, K, and Ba in the constituent minerals of the eclogites will be measured. Finally, analyses will be made of O and H isotopic compositions from the hydrous phases and these will be compared with similar measurements from coexisting garnets and clinopyroxenes. The ultimate goal is to better understand the igneous, metasomatic, and hydrothermal processes which contribute to the evolution of the earth's crust-mantle system.
