9505930 Taylor This is a comprehensive petrographic and geochemical study of eclogite xenoliths from the Siberian platform using a consortium of scientists, to establish the compositional and petrographical variation of eclogite xenoliths from Siberia. Major- and trace-element data will be collected on minerals by electron and ion microprobe. Bulk-rock compositions determined by x-ray fluorescence and instrumental neutron-activation analysis, and stable isotopic data (C and O) will be collected on mineral separates and bulk rocks (C isotopic compositions only on diamond). Radiogenic isotopic data (Sr-Nd-Os) will be collected on ultra-pure mineral separates and bulk rocks to evaluate the sources from which these samples were derived (e.g., crustal or mantle) and the age of these sources by model ages. Samarium-Nd isochrons from mantle xenoliths that are older than their host rock. Finally, a unique opportunity has presented itself in the form of five pairs of garnet-clinopyroxene inclusions which are hosted by diamonds and which, in turn, are hosted by eclogite modules from the Mir and Udachnaya pipes. A trace- and major -element study involving these paired inclusions and comparing them to the host eclogites is paramount to our understanding of eclogite and diamond formation and possible later metasomatism of the host. This study will be the first comprehensive detailed study of eclogite xenoliths from a northern hemisphere Archean-aged crustal segment.
