Mafic and felsic magma mingling and mixing in Alvand pluton: evidences of co-existing magma

Category Petrology
Group GSI.IR
Location 23th symposium on geosciences
Holding Date 05 May 2008

      Main volume of the Alvand pluton consists of porphyritic granite and gabbro that they are intruded by later pegmatite-aplitic veins. Relationship of gabbro and porphyritic granite appeared everywhere of pluton in interaction zone. Obviously, wide ranges of mafic-felsic magma mingling and mixing exist in interaction zone. Mingling evidences are lobate or/and ellipsoidal micro granular mafic enclaves sometimes with chilled margins in porphyritic granite or in hybrid rocks; net-veining granite; synplutonic brecciated mafic dikes. Coarse-grain alkali-feldspars phenocrysts in mafic rocks of interaction zone, biotitization of these rocks and intermediate rocks of gabbro and granite in interaction zone are obvious features of magma mixing. Abovementioned evidences demonstrate coexistence of the mafic and felsic (with exception of the pegmatitic) magma in Alvand area.
   Key words: magma mingling and mixing, coexisting magmatism, Alvand, granite, Iran.