Mineralogy, petrogenesis and tectonic setting interpretation of Kuh-e-Sarhangi area granites (northwest of Lut block)


1 Department of Geology, School of Basic Sciences, Tarbiat Modares University, Tehran, Iran

2 گروه زمین شناسی دانشگده علوم پایه دانشگاه بین المللی امام خمینی


Numerous granitic bodies have been injected into the Precambrian basement of Central Iran in Kuh-e-Sarhangi area. Microscopic investigations and mineral chemistry point to the existence of white mica, biotite and epidote as primary (magmatic) and secondary (alteration) or re-equilibrated types. The important mineralogical indicators such as the presence of two separate feldspars and the existence of spessartine-poor garnet and magmatic epidote indicate magma crystallization at relatively high depths. Whole rock and mineral geochemical evidences of these bodies show granitic composition, with calc-alkaline characteristics and weak per-aluminous nature. In discrimination diagrams, the studied granites are I-type belonging to volcanic arc. The spider diagrams pattern of these granites are resemble to the subduction zone magma. There is considerable compositional overlap of rare earth and trace elements patterns of Kuh-e-Sarhangi granites and continental active margin of southern Andes. Considering of continental active margin setting for Central Iran in upper Precambrian-lower Cambrian is the involvement of this micro continent setting in the northern edge of Gondwana and subduction of Prototethys oceanic basin underneath it. The existence of some anorogenic intrusion bodies with mineralogical and whole rock alkaline characteristics in this area is probably related to the extensional basins of back arc or the influence of deep lithospheric faults.