128 / 1971-01-01 00:00:00

Tectonic Setting Of Plagiogranites And Gabbros In The Shahre-babak Ophiolitic Sequence, (nain-baft B

,Shahre-Babak,plagiogranite,suprasubduction zone,volcanic arc,partial melt

Plagiogranite intrusive rocks crop out in the gabbroic section of ophiolitic sequence in the south east of the Shahre-Babak. Petrographically, they are comprised of tonalite, trondhjemite and gabbros are less differentiated to locogabbro type. Predominant textures plagiogranites are hypidiomorphic inequigranular, granophyry. Mineralogically, they are consisting of plagioclase, quartz, sodium feldspars as major minerals and less than 10% amphibole ± pyroxene, opaques. Gabbros consist of augite, plagioclase and amphibol as major mineral. Geochemical studies show that their magma is sub-alkaline (calc-alkaline series) and metaluminous type. Typologically, plagiogranites have characteristics of volcanic arc granite (VAG) and MORB toward I-type granites. Chonderite normalized REE patterns of Share-Babak plagiogranites and gabbroes show weekly light REE enriched along with a flat HREE patterns. it seems that they were formed in supra-subduction zone environment. It seems based on geochemical characteristics that parental magma of plagiogranties is reached partial melting of basic rocks such as gabbro at spreading basins associated with the subduction zone.