The Role of the Zagros Suture on Three Dimensional Deformation Pattern in Eghlid-Deh Bid Area of Iran

Abstract

Deformation pattern of the northeastern part of the Iranian-Arabian collision zone (i.e., mainly Sanandaj-Sirjan Belt or Zone) is the main concern of this paper. Here, we investigate the stress distribution and displacement pattern of Eghlid-Deh Bid area as affected by the position of Zagros suture using a three dimensional mechanical model. The modeled area is located between the Zagros Thrust Fault on the west and Deh Shir-Baft Fault in the east as its edges. The model is composed of 3 layers: the upper two layers represent the upper brittle and lower ductile crusts of the collided continent and the lowest layer represents lithospheric mantle. The bounding major faults are treated as vertical sides of the model. We introduced a discontinuity parallel with the Zagros Thrust Line at two different locations at the western margin and in the middle of the model to simulate Zagros suture to investigate its debated position and role on the deformation history in the area. Our results showed that stress and displacement patterns are fairly affected and disturbed by its position in the two cases. It could also have partitioned deformation across the study area particularly due to its marginal position. The modeled pattern of stress and displacement fields are both totally comparable with plate boundary shear zones demonstrating dextral transpression and more consistent with a suture zone located at or very close to the Zagros Thrust Line place. Such a conclusion is in agreement with recent field surveys including micro and macro-tectonic data.