My research focuses on the understanding of the present-day physical and chemical structure of the Earth's mantle and crust as well as its physical and chemical evolution over geologic time. Within this general framework, my research has covered a range of subjects from global questions addressing the causes and development of mantle heterogeneity, the interaction of the Earth's mantle with other major reservoirs (continental crust, core), and the estimation of the bulk composition of major Earth reservoirs, to more localized aspects of melt generation and melt evolution. Hereby, the development of analytical techniques for high-precision isotope and trace element measurements and the development of quantitative tools for the investigation of local and large-scale chemical cycles is an integral part of my research.