Garmichay S-type granites (northwestern Iran):Whole rock geochemistry, tectonic settingand generation mechanism

The Garmichay area in the north of Mianeh, NW Iran, features schists, amphibolites, calc-silicates, marbles and granitoids. Granitoids are of S- and A-type nature. Partial melting is the main generation mechanism, the progenitor is a pelite enriched in muscovite and the major melting reaction is muscovite dehydration. The ASI for the S-type granite varies between 1.12-1.5 indicating peraluminous character and crustal origin. Both granitic types are enriched in LREE in relation to HREE with negative Eu anomalies. Lan/Ybn ranges are 1.49-3.09 and 1.34-1.99 for the S-type and the A-type granites, respectively. Moreover, Lan/Gdn varies between 2.45 and 5 for the S-type granite and 1.53 and 1.75 for the A-type granite. The S-type granite has been generated in a collisional zone during Assyntic Orogeny.The A-type granite, however, is formed in a within-plate environment.The A-type granite belongs to A1 subtype formed in a continental rifting setting. The crystallization temperatures for the S-type and the A-type granites vary from 650 to 750 ºC and 800 to 850 ºC،respectively.