This grant is for continuing operation of the campus part of the Berkeley Center for Isotope Geochemistry. The research emphasis is on using isotopic and trace element measurements to elucidate the nature of solid earth geochemical cycles; in particular the focus is on processes related to the differentiation and evolution of continental lithosphere and its relationship to the structure and evolution of the mantle. The research includes field, laboratory, experimental and theoretical components. Analytical work includes measurements of isotope ratios of Ca, Nd, Sr, Pb, O and H on geological materials using clean chemistry laboratories and high precision mass spectrometric measurements. Activities proposed for the grant period are: (1) measurements of Ca isotopic ratios in island arc rocks and continental granitic rocks; (2) studies of crustal and mantle xenoliths in a transect from unrifted to recently extended craton to establish the nature of deep lithospheric modification during extension; (3) studies of the temporal evolution of basalt source regions during continental extension; (4) pilot studies of granitic petrogenesis in the USSR; (5) mathematical modelling of fluid-rock interaction and magmatic processes.
