From mantle geodynamics to environmental processes: a geochemical perspective

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Modern geochemistry is concerned with quantifying and explaining the transfer of elements within and between the different major geological reservoirs of the Earth, including the mantle, the crust, the oceans, and the atmosphere. Geochemistry provides answers and tools for the fundamental understanding of our planet, including the environment, global change, resources, human health and natural hazards. Such research requires precise analysis of isotopic ratios and elemental concentrations in rocks, minerals, water, or organic matter. Multiple collector inductively coupled plasma mass spectrometers dramatically expand the potential isotopic systems that can be measured and allow for unprecedented sensitivity and precision. I propose to investigate three main themes of geochemical applications: 1) Earth's mantle and solid earth, 2) environmental impact, and 3) analytical developments in mass spectrometry. As the Earth's deep interior cannot be sampled directly, geochemists rely on analyzing basalts to infer the composition of the mantle. I propose to study two of the largest modern mantle plumes (Hawaii and Kerguelen) that originate in the deep mantle and, as well as Cascade Arc volcanoes and sediments to model the amount of recycling into the mantle. The results of this research will contribute to the global understanding of the composition and distribution of components in the mantle and their variation over geologic time. In the environmental theme, I will use heavy stable isotope systems (Cd, Zn, Si coupled with Pb) to investigate element cycling and metal pollution in marine and terrestrial systems. This work will increase our understanding of ancient climates and oceanographic conditions and has implications for British Columbia fisheries and aquaculture industry. Research within the third theme includes systematic studies to characterize reference materials and identify problematic matrix effects during mass spectrometry. This work will lead to an invaluable reference database and methodology for the scientific community. The overall objective of the proposed 5-year research program is to evaluate the geochemical evolution of our planet and its environment through the use of new analytical possibilities in isotopic geochemistry.