The Alkaline-Peralkaline Tamazeght Complex, High Atlas Mountains, Morocco: Mineral Chemistry and Petrological Constraints for Derivation from a Compositionally Heterogeneous Mantle Source

a multiphase alkaline to peralkaline intrusive complex. A large vari-ety of rock types (including pyroxenites, glimmerites, gabbroic to monzonitic rocks, feldspathoidal syenites, carbonatites and various dyke rocks) documents a progression from ultramafic to felsic mag-matism.This study focuses on the silicate plutonic members and the genetic relationships between the various lithologies. Based on detailed petrographic and mineral chemical data we show that the various units crystallized under markedly different oxygen fugacity and silica activity conditions and demonstrate how these parameters influence both the phase assemblage and the detailed chemical evolu-tion of the fractionating phases. Nepheline, olivine^clinopyroxene and hornblende^plagioclase thermometry indicate equilibration temperatures 8008C for all major rock types. Highly oxidized conditions (close to the hematite^magnetite buffer) are characteris-tic of the garnet-rich pyroxenites, ultrapotassic glimmerites and