Providing a new tectonic model for Khoy area in the northwest of Iran

Category Tectonic & Seismotectonic
Group GSI.IR
Location 20th symposium on geosciences
Holding Date 16 April 2008

     Metamorphic rocks are exposed north of Khoy (northwest Iran) between ophiolites and non—metamorphosed Palaeozoic rocks located to the northwest and east respectively, where all are overlain unconformable by the Qum Formation of Oligocene—Miocene. Two types of metamorphic rocks exist. Metabasites are amphibolites and green—sehist where metasediments are micaschist, garnet stanrolite and sillimanite schists. Marble, quartzite and meta—arcose are also seen in the sequence.The protolite of The metabasites are kalko—alkalinc toleait ic gabbro and hasalt where the metasediments are mostly pellitic, carbonates and detritic rocks like conglomerate and sandstone. Grade of metamorphism range between green— schist to upper amphibolitc ficies. Geofermobarometry of the minerals by several ways indicate The average heat of 500o 280o and 5.5
-7.5 Kb pressure. High amount reduction of pressure (about 2 Kb) in the marginal zone of the minerals with about steady temperalure clear a normal Ht. M FG diagram presents a progressive matamorphism where the thermal gradient was about 27o—30o per each kilometer depth. This amount is very similar to the thermal gradient of the continental collision zones. These data clear that the metamorphic rocks of the north Khoy is the result of thickening of the crusf through the collision boundary of the Arabian platform and Azarbaidjan (northwestcrn part of the central iran) during Eocene.