Ophiolite Series and Ultramafic Rocks

Ophiolite series and ultramafic rocks have a widespread occurrence in Iran and can be grouped as follows: Ultramafic and mafic units of Late Precambrian–Early Cambrian. Although comparable to modern ophiolites, these rocks do not display all typical features of an oceanic crust. The term “old ophiolite” might be a misnomer.

These rocks are widespread in Takab and Anarak Regions. They might be representing a protorift. Ultramafic and mafic rocks of Upper Paleozoic occur as metamorphosed as well as non-metamorphosed bodies in some areas like Fariman, Shanderman, and Asalem. These rocks display many typical features of modern ophiolites. Ophiolite series of Early Cretaceous–Paleogene age show typical features of ophiolitic sequences and are thought to be associated with the closure of the Neotethys. These ophiolite series are widespread in Iran. Some of the more important locations include Kermanshah–Neyriz–Oman Belt, Makran (south of Jazmurian), ultramafic–mafic rocks related to Flysch Zone in Khash–Nosrat Abad–Birjand Belt, ultramafic and mafic rocks north of Dorooneh fault, Torbat-e Jam–Torbat-e Heydarieh–Sabzevar–Fariman regions, and Central Iran–Nain–Baft–Shahr-e Babak, Khoy–Maku. Ultramafic and mafic rocks also occur in association with large gabbroic intrusions. This type probably resulted from differentiation in a large mafic magma chamber, comparable to those of the layered mafic intrusions. Examples occur in Sero, Urumiyeh, and in Masooleh that are Late Cretaceous to Lower Oligocene in age. The most remarkable occurrence of ophiolite could be observed in the Bashagard Mountains in the southeast and the Jaghatai Mountains in the northeast of Iran.

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