Using geochemical tools to answer natural questions ranging from mantle dynamics and subduction zone processes to paleo- and present-day climate and environmental change. Primary tools include major and trace elemental concentrations, radiogenic isotopes (Sr-Nd-Pb-Hf-Os), non-radiogenic isotopes (B, Li), as well as geochronology (K-Ar, U-Pb, Sm-Nd, Lu-Hf).