شناخت گسلهاي پنهان و ارتباط با آن با دگرشكلي هاي موجود در جنوب خاور زاگرس با استفاده از رهيافت دورسنجي

Studies of Basement Faults and their Deformational Style in Southeast Zagros by Application of Remotely Sensed (RS) Method

The study area is located in southeast of the fold-thrust belt of Zagros. The belt is influenced by sub- surface structures and the creation of young deformations during the late Alpine Orogeny. Remotely sensed data showed that the area suffered structural complications due to the influence of the superimposition of deformation resulted from the younger transverse lineaments over the foreland fold-thrust structures. Two systems of sub-surface transversed faults have been identifie, using the visual interpretation of satellite images, review of the evidences such as curvilinear hinge geometry of the folds and the existance of similar deformations in the sub-surface structures, formatin of different folded trends, axial interaction of the folds, generation of brachyanticlines, and alignment of the upper proterozoic salt plugs. The first system has an identified trending 0 to 90 on the basis of their left-lateral displacement of the fold-thrust structures and trend of the salt plugs. While the second system, trending 270 to 360 has a lower capability in diapirism and outcrop of the salt plugs; Therefore, a weak alignment of salt plugs is observed in their trend. On the basis of the curvilinear folded geometry in the foreland part of the orogen, right-lateral displacement was analyzed for this system. while Statistical analysis of the structural lineaments extracted from the satellite images shows that the principal stress axis, trending 20, is more dominant in the area. The performance of this stress resulted in two systems of conjugate shear faults with dominant strike-slip component. The left - lateral strike-slip component is observed in the sub-surface faults trending 0 to 90. The right-lateral strike-slip component is visible in the sub-surface faults trending 270 to 360. With respect to various similarities in statistical hystograms of the structural lineaments of southeast and northwest of Zagros, the suggested structural pattern in the area under study, could probably be applicable for all of the Zagros. Furtheremore, the suggested structural pattern could assist to verify and explain some of considered probable reasons for the inconsistant distribution of the salt domes in the area. The northern part of Iraq and southeast of Zagros, the north and northeast margins of the Arabian plateau, have many similarities with the basement tectonic pattern of the northeast Arabic plate in Saudi Arabia. The similar trend of most conjugate shear faults and also the brachyanticlines (in the area of study) with the strike of the basement faults and their overlaping young folds in the northeast of the Arabic plate in Saudi Arabia indicate that these faults are deep-seated and therefore of basement type.