The geodynamic significance of the correlation of the Khoy ophiolites in northwest Iran with ophiolites in southeast Turkey
Published:December 21, 2017
Morteza Khalatbari Jafari, Hassan A. Babaie, 2017. "The geodynamic significance of the correlation of the Khoy ophiolites in northwest Iran with ophiolites in southeast Turkey", Tectonic Evolution, Collision, and Seismicity of Southwest Asia: In Honor of Manuel Berberian’s Forty-Five Years of Research Contributions, Rasoul Sorkhabi
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The Khoy area in northwest Iran is composed of five major geological units that, from east of Khoy to the Iran-Turkey border, include the southwestern edge of Central Iran, the Eastern metamorphic complex (including its meta-ophiolitic complex), Upper Cretaceous–Lower Paleocene supra-ophiolitic series, an Upper Cretaceous non-metamorphic ophiolite complex, and the Western metamorphic complex. The main objective of this paper is to compare the geology of the Khoy ophiolites in Iran with similar units in neighboring southeast Turkey. The Neoproterozoic m1 basement unit of the Eastern metamorphic complex in Iran was part of a large continental block that also included the basements of the Central Iran microcontinent, the northern margin of Gondwana, and the basement of tectonic units in Turkey. The continental crustal block was split along a rift in northwest Iran–southeast Turkey after the oceanic crust and related suprasubduction series were formed during the Late Triassic–Early Jurassic. The subduction of the eastern margin of the oceanic crust under Central Iran led to the metamorphism of the crust and supra-ophiolitic series to the greenschist-amphibolite facies and formation of Khoy’s Eastern metamorphic complex during the Middle Jurassic–Late Cretaceous. The meta-ophiolitic part of the Eastern metamorphic complex in Iran probably correlates with the Berit mountain meta-ophiolite in the southeast Anatolian region in Turkey. Continued subduction in the east and accretion onto Central Iran led to the injection of Upper Cretaceous– Lower Paleocene granitoid masses.
The oceanic crust developed an extensive plutonic sequence and the thickest (>1000 m) extrusive sequence among Khoy ophiolite massifs during the Late Cretaceous. The Upper Cretaceous Khoy ophiolite is nonmetamorphic and can be correlated with the ophiolite massifs in the northern ophiolite belt of the southeast Anatolian region in Turkey, such as Berit (Göksun), İspendere, Kömürhan, and Gulman. The southeast Anatolian ophiolite massifs, however, stand above and below the Bitlis-Engizek metamorphic complexes and represent different tectonic units. In contrast to the ophiolites of the northern belt in the southeast Anatolian region in Turkey, which show suprasubduction geochemical characteristics, the Khoy extrusive sequence displays transitional (T) mid-ocean-ridge basalt (MORB)–like and normal (N) MORB-like patterns, and it is cut by diabase dikes with suprasubduction-zone compositions, indicating a geodynamic transition from a MORB to a suprasubduction setting before the injection of the dikes in the Late Cretaceous–early Paleocene. The Khoy supra-ophiolitic series, which evolved in a trough along the eastern margin of the Late Cretaceous ocean, correlates with the Elaziğ volcano-sedimentary rocks in the southeast Anatolian region in Turkey. The Eocene volcano-sedimentary rocks in the Khoy area can be correlated with the Maden group in Turkey, which has been defined as a volcano-sedimentary succession of middle Eocene age, representing a short-lived back arc basin. Upper Miocene quartz monzodiorite masses with a subduction geochemical signature are the youngest intrusions that cut the supra-ophiolitic series and Upper Cretaceous ophiolitic rocks in Khoy.