9526344 Halliday This project will develop the new technique of ICP magnetic sector multiple collector mass spectrometry (MC-ICPMS) for application in two areas of relevance to petrology and geochemistry - higher resolution geochronology and precise in situ isotopic measurements. MC-ICPMS combines the advantages of very efficient plasma ionization with the precision of multiple collector magnetic sector mass spectrometry. The addition of a laser facilitates studies for which spatial resolution is needed. The P.I.s will focus their development work in new techniques that provide a capability not well duplicated by other methods. In particular, high sensitivity U-Th measurements on low 230Th/232Th samples, Hf isotopic studies of small samples and high precision in situ laser Sr, Pb, and Hf isotopic measurements will be made with MC-ICPMS. In the first instance the P.I.s propose using these methods for Sr and Pb isotopic studies of fluid inclusions, elucidating magmatic histories using high precision in situ isotopic measurements, U-Th disequilibrium studies of igneous systems, Hf isotopic studies of zircons and the determination of P-T-time paths using microscopic mineral inclusions.
