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| دسته | تکتونیک |
|---|---|
| گروه | سازمان زمین شناسی و اکتشافات معدنی کشور |
| مکان برگزاری | بیستمین گردهمائی علوم زمین |
| نویسنده | حسین، عزیزی؛ حسین، معین وزیری؛ محمد، محجل |
| تاريخ برگزاری | ۱۸ بهمن ۱۳۸۰ |
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-schist where metasediments are micaschist, garnet staurolite and sillimanite schists. Marble, quartzite and meta-arcose are also seen in the sequence. The protolite of the metabasites are kalko-alkaline toleaitic gabbro and basalt where the metasediments are mostly pellitic, carbonates and detritic rocks like conglomerate and sandstone. Grade of metamorphism range between green- schist to upper amphibolite facies. Geotermobarometry of the minerals by several ways indicate the average heat of ۵۰۰؛ – ۶۸۰؛ and ۵.۵ – ۷.۵ Kb pressure. High amount reduction of pressure (about ۲ Kb) in the marginal zone of the minerals with about steady temperature clear a normal Ht. MFG diagram presents a progressive metamorphism where the thermal gradient was about ۲۷؛-۳۰؛ 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 crust through the collision boundary of the Arabian platform and Azarbaidjan (northwestern part of the central iran) during Eocene.