Measurements of the isotopic composition of the elements Sr, Nd, Ca, and O, and concentrations of Rb, Sr, Sm, Nd, K, Ca, and other major and trace elements will be made on rocks and minerals in order to address problems pertaining to the evolution and geochemical structure of the continental crust, the evolution of magmas in the crust, and the isotopic evolution of the mantle in Precambrian time. Particular problems that will be addressed are the composition of the lower parts of the continental crust (with K-Ca isotopes in conjunction with Rb-Sr, Sm-Nd, and O), the introduction and dispersal of contaminants into mafic magma chambers and the implications for magma chamber convection and crystallization modes, and the Sr isotopic evolution of the mantle in Proterozoic time and its implications for continental lithosphere recycling and models for crust-mantle evolution. Subjects of study will be island arc rocks and systematic collections of granitic rocks from Precambrian terranes for the K-Ca studies, the Stillwater and Muskox intrusions for the magma chamber studies, and ca. 1.8 Gyr mafic and intermediate intrusive rocks from central Arizona for the mantle evolution studies. This support is for a time period of less than one year in order to complete ongoing activities prior to the completion of a new laboratory at the University of California, Berkeley.
