Geochemistry and petrogenesis of plagiogranites in the Neyriz ophiolitic sequence, Iran: Constraints on their origin

Plagiogranite intrusive rocks are outcropped in the gabbroic section of the Neyriz ophiolitic sequence in the south east of Shiraz. Petrographically, they are comprised of tonalite, trondhjemite and their contact with surrounding gabbros is either sharp or covered. Predominant textures are hypidiomorphic inequigranular, granophyry and micrographic. Mineralogically, they are consisting of plagioclase, quartz, sodium feldspars as major minerals and less than 10% amphibole ± pyroxene, opaques and rarely titanite and zircon as minor minerals. Geochemical studies show that their magma is sub-alkaline type (calc-alkaline series) and metaluminous. Typologically, plagiogranites have characteristics of oceanic ridge granite (ORG) toward I-type granites. Chonderite normalized REE patterns of Neyriz plagiogranites show depletion in LREEs along with a flat HREE patterns and it seems that they were formed in supra-subduction zone environment by partial melting of mafic rocks which in turn were formed by the anatexis of a previously depleted harzburgitic mantle.