Document Type: Original Article

Authors

1 Master of Tectonics, Department of Geology, Ferdowsi University, Iran.

2 Department of Geology, Ferdowsi University, Iran.

Abstract

The geometric and kinematic analyzing of the anticlines and their relation with the large-scale structures are used to determine the structural evolution of the area. The Dorbadam anticline is located in the Kopet-Dagh structural zone, 45 km due north of Quchan and on the Razavi and North Khorasan provinces border. The field study and geometric analysis indicate that the Dorbadam anticline has two culminations with an en-echelon arrangement and different structural evolution. The NW culmination (DA.1) is analyzed as a fault propagation fold geometry, while the SE culmination is known as a simple folding. The axial trend of the Dorbadam anticline has been changed and shows harmonic and Horizontal inclined, 1C subclass of Ramsay's classification, close, asymmetrical over fold in DA.1 part; upright and horizontal, open and symmetrical upright fold in DA.2 part. Aspect ratio on the Dorbadam anticline is 0.64 and has a parabolic appearance. The joint study revealed the existence of five major joints in this area which are bedding and strike joints (tension and compression joints parallel to the axial fold) or dipping joints (tension joints). The systematic joints analyzing of Tirgan Formation with T-Tecto software determined that the trend of maximum stress in the Cretaceous was S07W. The paleo-stress direction determined S25W with axial plane analysis. The Analysis of large-scale faults indicated a change in the stress direction during the time and specified they are post-tectonic and the activity of faults occurred in some various stress systems.

Keywords