Geochemistry and source of tourmaline from the Soheyle-Pakuh granitoid body (North of Nain)

The Oligocene Soheyle Pakuh granitoid body is located in the Urumieh- Dokhtar zone, which composed predominately of granodiorite, diorite and granite with mafic, aplite dikes and iron-tourmaline veins. On the base of geochemical characteristics, the composition of the tourmalines is schorl-dravite series with more tendency toward schorl component. The R1 versus R3 diagram as well as by changing the tuormaline composition from Schorl to Dravite, depletion from alkali increases. Using of the Ca-Fe-Mg and Al-Fe-Mg ternary diagrams display that the The tourmalines from the Soheyle Pakuh granitoid body associated with quartz- tourmaline, meta- pelites, ca- depleted meta- psamite and meta- pelites associated with Al-phase. Oscillatory chemical zoning in the tourmaline crystals by increasing of Mg, Na and Al values in the rims than to the core, point to effect of the hydrothermal fluids. The substitution process in the structure of the tourmalines Soheyle Pakuh granitoid body mostly in accordance with the AlNa-1Mg-1,lOMg-1(OH)-1 AlOR2 -1(OH)-1, Al(NaR)-1 FeAl-1exchange vectors. Since, the FeO/FeO㈃ ratio for is limited to 0.60-0.79 values, therefore, their source may be supposed by the way from magmatic system to a hydrothermal environment.