This project addresses one of the fundamental issues about the evolution of the Earth ? how continental form and grow through time. Cratons are the oldest and most stable parts of our continents and act as the nuclei for the formation and growth of our continents. Stable and old cratons are believed to be formed early in the history of our planet through a process that involves the extraction of magma that eventually yields a compositionally buoyant crust and underlying lithospheric mantle. Old cratons such as the Kaapval Craton in South Africa, Slave Craton in Canada, and the Siberian Craton in Russia are well-known for their occurrences of diamond-bearing kimberlites as well as the sites for finding other valuable mineral resources. Because these cratons are deep and we cannot sample them adequately through drilling, their study require access to samples of the deep Earth (xenoliths, diamonds, diamond inclusions) that are carried to the surface in explosive volcanic eruptions (kimberlites, lamproites). The Siberian Craton contains >1000 kimberlites that are distributed across the craton and contain evidence that will be used to reconstruct the formation, development, and evolution of this core of the upper Asian continent. The proposed research will be conducted as a consortium effort, built on a formal scientific treaty between the University of Tennessee (UT) and the V.S. Sobolev Institute of Geology and Mineralogy in the Siberian Branch of the Russian Academy of Sciences (IGM) in Novosibirsk, under the direction of Akad. Nickolai P. Pokhilenko.
The research plan includes the investigation of geochemical and mineralogical variations of peridotite xenoliths from kimberlite pipes of different age groups across the Siberian Craton in order to address the following questions: a) What were the composition and thermal structure of its sub-continental mantle over time; b) What were the styles, processes, and sources of metasomatism that occurred in the mantle and their timing; and c) What were the conditions and time scales of the metasomatic events that led to the formation of zoned garnets (sub-calcic to eclogitic) in peridotite xenoliths? It is expected that these various data sets will be integrated to provide a more comprehensive view of the Siberian craton.
