9505770 Haggerty The primary objective is to test the Core/Mantle Boundary-plume origin by studying the geochemistry and mineralogy of kimberlites and entrained xeonoliths. Theoretical, experimental, and geochemical templates will be applied to identify the various components that have been sampled along the 2900 km conduit. One section of the conduit, between 410 and 660 km (the transition zone, TZ), is of particular interest because the boundaries are marked by dense mineral phase transitions, deep focus earthquakes, high pressure minerals capable of water retention, and a layer that may harbor the accumulation of subducted ocean floor basaltic slabs. A second objective is to place limits on the extent of chemical heterogeneity, and to describe the geology of the TZ. This will be done through a mineral and geochemical study of ultradeep xenoliths, eclogites (high pressure basalt), and xenoliths modified by fluidal melt processes (metasomites). A third objective is to study an unusual form of diamond known as carbonado, which is sintered but also porous. Resolving the origin of carbonado will have geological implications and technological applications. These studies will be undertaken on rocks from South Africa, Botswana, and Sierra Leone, and on carbonado from Brazil. Standard techniques with state-of-the-art instruments, will be applied to the study in laboratories at the University of Massachusetts, and in collaboration with other institutes.
