Petrology and geochemistry of Aliabad-Daman granitic body (Rashtkhar, Khorassan-Razavi)

Aliabad-Daman granitoid body with NW-SE trend is located in northeastern of the Rashtkhar city (about 15 km) with an area of approximately 10 km2. This body with probably age of middle Jurassic is located above Darouneh fault and is part of Sabzevar zone. This pluton consists of alkali feldspar granite, syenogranite and monzogranite. In the discriminant diagrams of micas, biotites plot in the field of syderophyllite and are generated from the crystallization of magma. The plagioclase is in the field of albite to oligoclase and orthoclase resemble to anortoclase due to its micro-perthitic occurrence. Chlorite located in the field of repidolite and brensovigite which indicate its iron-rich composition. Based on petrographic and geochemiscal studies Aliabad- Daman granitic pluton resemble with A2-type granites with slightly peraluminous nature. Negative Ba, Nb, Ti, Sr and P anomalies in discrimination tectonic setting diagrams indicate that they are generated in a volcanic arc setting. Extensional environment in a continental arc has provided conditions for generation of these granitic rocks.