Mesozoic plutons in the Klamath Mountains province (CA) intruded a structurally deformed oceanic crustal section and represent the eroded roots of an island arc volcanic belt. Emplacement of these magma brackets a major tectonic episode (the Nevadan orogeny) during which the style of magmatism changed significantly. This proposal will involve a detailed geochemical and petrologic study of four plutons spanning this time interval. Mineralogical data will be acquired to evaluate physical conditions (pressure, temperature, etc.) attending magma formation during the transition in magmatic style. Geochemical and isotopic data will be used to elucidate processes of magma evolution. This integrated study will hopefully provide important insights into the deep crustal processes associated with island arc magmatism.
