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The Kopet Dagh Mountains in NE Iran result from Cenozoic tectonic inversion of Triassic and Jurassic rifts that formed along the southern margin of the Eurasian continental plate. The Kopet Dagh defines an arcuate orogen leading to the suggestion that oroclinal bending took place during its formation. We performed a paleomagnetic study including seven sampling sites of Paleocene formations around the Kalat syncline in the East Kopet Dagh to test whether this part of the mountain belt experienced vertical-axis rotation. Paleomagnetic measurements and a reversals test indicate that parts of the collected samples may have been partially remagnetized. Overall paleomagnetic directions of all sample sites show a mean declination of 12.5°, which is the expected direction for stable Europe in the Paleocene and therefore negates any rotation related to regional tectonic events. Directions calculated only from reversely polarized paleomagnetic data, however, suggest clockwise vertical-axis rotations up to 21° since the Paleocene. Numerical modelling of a viscous multi-layer folding mimicking the Kalat syncline stratigraphy suggests that local deviations in overprinted site-mean directions and orientation of the maximum axes of the AMS ellipsoid may be related to complex folding kinematics, acquired after regional vertical-axis rotation, where related viscous flow of relatively weak interlayer is represented by the sampled Paleocene formation. [ABSTRACT FROM AUTHOR]

In northeast Iran, the suture zone of the Paleotethys is situated between the East Alborz Mountains to its south and the Kopet Dagh Mountains to its north. Both mountain belts represent large-scale oroclines, potentially resulting from the indentation of the quasi-rigid South Caspian Basin. The oroclinal shape of the Alborz Mountains has been associated with vertical-axis rotation based on paleomagnetic data. However, no evidence for rotation has been found in the northeastern Kopet Dagh. A plausible scenario is that most of the rotation in the Kopet Dagh has been absorbed along its western part. Here, we present results of vertical-axis rotation and anisotropy of the magnetic susceptibility (AMS) for sites located in the West Kopet Dagh. AMS data range from sedimentary to tectonic fabrics depending on the position with respect to local thrusts. Magnetic vectors do not show significant vertical-axis rotation, implying that no significant rotation took place since Cretaceous times in the western Kopet Dagh. A preliminary comparison of these results with previous data from East Kopet Dagh favours complex local folding kinematics for most of the Kopet Dagh rather than significant vertical-axis rotation. [ABSTRACT FROM AUTHOR]