Petrography and Major-Element Geochemistry of the Gharebagh Phlogopite Deposit, North-Western Iran

The gharebagh phlogopite deposit hosts phlogopite megacrysts up to 30 cm in diameter. it is associated with syenite intruded by mafic dykes. phlogopite-bearing glimmerite veins are oriented along the dykes. the glimmerite is accompanied by a metasomatic sequence consisting of largely monomineralic, pyroxene-rich transition rocks and metasomatic, dark syenite. petrography revealed abundant reaction textures in syenite host rock and mafic rocks. comparing mineral relationships across host rocks and metasomatic rocks with data from whole-rock geochemistry indicate that k2o, mgo, cao, and na2o were highly mobile. we suggest that the deposition of those elements was controlled by the phlogopite crystallisation. the phlogopite accumulated k2o and mgo, whereas excess material was either incorporated in transition rocks (cao) or transported further (na2o). the abundance of calcite in all rocks suggests that co2 played a major role in the metasomatic process