This award is for a year of development of U-, Th-disequilibrium analyses utilizing high precision thermal ionization mass spectrometry in the Keck Center for Isotope Geochemistry at UCLA. The requested funds will largely support personnel critically needed at this stage to develop protocols for the Th isotope analyses, and to perform and interpret the first generation of analyses on the new dual sector mass spectrometer. Using Th isotopic analyses, the PIs will evaluate the temporal and chemical evolution of magma processes for the lava fields of Craters of the Moon, Idaho, and Pisgah crater, California. Both fields have been interpreted as erupting from magma chambers which have undergone crustal assimilation, albeit of silicic material in the case of the former and mafic material in the case of the later. They will then investigate paired Th-Pb isotope systematics of selected lavas from diverse tectonic settings in the western U.S. for their utility in characterizing lithospheric (crust and Mantle) versus asthenospheric components to magmagenesis.
