Interpretation of the Central Metamorphic terrane metabasites as the lower-plate of a Devonian intraoceanic subduction zone is a basic tenet of paleotectonic models for the eastern Klamath province. Specifically, such models hold that the (1) east-dipping Central Metamorphic terrane represents a subducted piece of oceanic lithosphere accreted to the overlying Trinity subterrane; (2) Trinity and Redding subterranes represent mantle and magmatic-arc crust of the overriding lithospheric plate; and (3) east-dipping Trinity thrust, separating the Central Metamorphic terrane and Trinity subterrane, represents the paleo-plate boundary. The subduction-zone model predicts that mid-ocean ridge basalt (MORB)-type oceanic basalts formed the protolith of Central...