The North Sistan orogen (Eastern Iran): Tectono-metamorphic evolution and significance within the Tethyan realm

The Sistan orogen (Eastern Iran) separates the Afghan and Lut continental blocks stretches along ?700 km from north to south, at a high angle with respect other, dominantly E-W trending Alpine-Himalayan orogens. This study reappraises tectono-metamorphic evolution of northern part orogen, as well its significance within Neotethyan realm. Detailed inspection ophiolite indicates that Ocean was slow-spreading type that, given structural patterns, petrological characteristics age, it opened in transtensional setting ?125 Ma ago. Closure took place through major NE-dipping subduction zone, formed no later than 90 Ma, shown by location age bimodal juvenile arc magmatism, SW vergence subducted fragments. discovery metamorphic sole base (?750 °C–0.65 GPa) argues for onset an additional intra-oceanic thrust/subduction zone around 74–72 which resulted south-westward obduction preservation onto block. therefore appears have recorded two geodynamic events accompanied closure Neotethys, i.e. change kinematics ?105 ± 5 northward migration India ?75 70 onwards. Subsequent collision, likely started during Paleocene mostly completed Oligocene, drastic Eocene sedimentation yet only moderate shortening (?30–50 total). Since Late Miocene onwards, post-collisional deformation is dominated far-field stresses related Zagros collision.