Age of the Eastern Iranian oroclinal Buckling inferred from a U235/Pb207 dating on radial dikes in the Qayen Area

The Eastern Iranian Orocline provides us several opportunities to study magmatism in relation to tectonic events. The buckling of this orocline is accompanied by an extreme extension in its Khorasan outer arc during which a calc-alkaline dike swarm, generally andesite to dacite, intruded in a radial pattern into the Paleocene-Eocene volcano-sedimentary units, belonging to the platform of the Lut block. The azimuth of these dikes shows a declination of 30 degrees, from N300^o to N330^o. The U²³⁵/Pb²⁰⁷ age of ~41±74 Ma from zircon crystals taken from the dikes represents a considerable buckling with an extension occurred during the middle-upper Eocene. In fact, this time refers to the buckling in the boundary of the inner- and outer-arc of the orocline. This could be a noticeable document of syn-orocline magmatism in the Tethyan realm in the east of the Iranian plateau. The dikes and their host rocks are also sampled for AMS analysis and paleomagnetic measurements to test the amount of the oroclinal buckling in the Qayen area.