petrogenesis of plutons of west of baneh

baneh pluton is located in northwest of kordestan province and sanandaj-sirjan zone. this body has been injected into low-grade metamorphic rocks in cretaceous and so it is attributed to upper cretaceous-paleocene. this complex is composed of three distinct intrusive phases. these phases are diorite, biotite-granite and garnet-bearing granite. diorites is the first constituent unit that is intruded by biotite granite in some areas. in other areas interaction of these two bodies is clear. therefore, biotite granite has intruded simultaneousey with diorite or sometimes after it. garnet-bearing granite is the youngest unit of this complex that usually intrudes as dyke in to biotite granite. there are hornblende, titanite and magnetite in diorites, also asi>1, cipw-normative diopside and high degree of cao, na2o, sr suggest that diorite related to i-type granitoides. the aboundant existence of biotite, muscovite and surmicaceous enclaves in biotite granite and presence of garnet in garnet-bearing granite classify them under s-type group. furthermore, asi>1, cipw-normative corundum and high degree of rb, k2o is used as an evidence for this issue. from tectonic setting point of view,baneh pluton is located in vag granitoides which is related to continental subduction zone. geochemical data indicates that diorites originates from enriched mantle over the subduction zone or from subducted oceanic crust. biotite granites and garnet-bearing granites are produced by fractional melting of metasedimentary rocks. some biotite granites have a metapellitic origin and others are derived from metagreywacks where garnet-bearing granites are the product of fractional melting of metapellitic rocks.