Mineral Chemistry and The emplacement mechanism of Gholeh-Sukhteh intrusion, geodynamic implication of the Oligocene in (South Damghan area)

Gholeh- Sukhteh sub-volcanic intrusion as part of the Toroud – Chah-Shirin magmatic belt, is located in the northern part of Central Iranian structural zone. A volcano-pyroclastic sequence of Eocene including of red-purple tuffs, volcanic breccia, and agglomerate is the host rocks. In order to investigation of the emplacement mechanism of this sub-volcanic intrusion, anisotropy of magnetic susceptibility (AMS) is used. The pluton is dioritic porphyry and belongs to ferromagnetic and magnetite series granites. Presence of magnetite is confirmed by microscopic observations and mineral chemistry. The highest degree of anisotropy (P%) that is sign of strain, is observed at the northern east to west - southwest of the intrusion. Highest areas and around the roof of Gholeh-Sukhteh intrusion, shaped parameter (T) is oblate. Some stations at the south-western part of intrusion have high-plunge magnetic lineations and prolate shape parameters. This part can be considered as feeder zone. Furthermore, the circular to ellipsoid shape of the pluton, roughly concentric magnetic pattern through the sub-volcanic intrusion, intense crushing and deformation at the country rocks especially at western margins are the main evidences that the pluton emplaced as a balloon.