Acquisition of a State-of-the-Art Multi-Collector Inductively-Coupled Plasma Mass Spectrometer

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This project is supporting the acquisition of a new, state-of-the-art Multi-Collector Inductively-Coupled Plasma Mass Spectrometer (MC-ICP-MS) for the Department of Geology of the University of Maryland at College Park (UMD). This type of instrument uses a high temperature plasma to efficiently ionize elements in a given sample of material so that the relative abundances of different chemical elements can be determined very precisely. The instrument has multiple detectors which are used to simultaneously quantify the intensity of ion beams of different isotopes of a given element, allowing high precision isotopic analysis. The new instrument is replacing an aging (17 year old), increasingly unreliable, first generation Nu Plasma instrument we currently utilize, and will facilitate current NSF-sponsored research, as well as anticipated future research needs. The instrument will be used to make high precision measurements of the isotopic compositions of a number of chemical elements. These measurements are used to study, for example, the chemical evolution of the Earth, interactions between rocks and fluids, and ore formation processes.The requested instrument will permit researchers at the University of Maryland to precisely measure the isotopic compositions of Li, Sr, Pb, and Ru extracted from rocks hosting comparatively low concentrations of these elements, and will also allow continued pursuit of high precision measurements of siderophile element abundances in various mantle and crustal rocks by means of the isotope dilution method. Specific analytical tasks to be tackled with the proposed new MC-ICP-MS instrument include: 1) high precision Li isotopic analysis of mantle and crustal rocks, including subduction zone related rocks, as a means of studying fluid flow in the crust and the weathering history of the continents, 2) high precision measurement of siderophile element abundances to constrain the origin and evolution of silicate reservoirs in early Earth history, as well as to study the roles of partial melting and mantle metasomatism on the chemical evolution of the mantle and crust, and 3) the study of Pb isotopes in crustal rocks as a means of constraining heat production. Aspects of each of these tasks are currently supported by NSF grants, and are also likely to be targeted by future research of our group.