Petrology, geochemistry and geochronology of Nodoushan intrusive complex, West of Yazd

The Nodoushan intrusive complex is a part of Cenozoic plutonism, which located in the central part of the Urumieh–Dokhtar Magmatic Belt (UDMB). This complex consists of four main intrusives, including diorite, granite-granodiorite, diorite porphyry and granodiorite. Mafic microgranular enclaves (MMEs) are abundant in the diorite porphyry and granodioritic intrusives and also in some parts of Granitegranodiorite intrusives, which consist of diorite, monzodiorite and rarely gabbro -diorite. According to geochemical data, the Nodoushan intrusive complex is metalominous to moderately peraluminous, I-type and shows medium to high potassium calc-alkaline affinity. Geochemical investigations show that contamination and mafic-felsic magma mixing played significant role in the evolution and petrogenesis of the mentioned intrusions magmas and formation of MMEs. Using U-Pb zircon dating method, the obtained magma crystallization ages are about 30 Ma for the dioritic and granite-granodiorite intrusives, 24 Ma for the diorite porphyry and 25 Ma for the granodioritic intrusives. In addition, the age for part of the granite-granodiorite unit that is located in the northeast corner of the region, at the north of the Nain-Dehshir fault (NDF) and the western part of the Central Iranian Microcontinent (CIM), was determined 40 Ma. The geochemical evidences suggest that the studied intrusions magmas were derived from partial melting of continental crust caused by the mantle melts in an active continental margin. It seems that the melting of rocks with combination of metabasalt and metagraywacke in the lower crust in balance with the residual consisting of clinopyroxene, amphibole and to a lesser extent plagioclase; have the greatest harmony with geochemical characteristics of the studied intrusions.