Effect of the perpendicular faults interaction on the Rag Sefid and Tango folds evolution (SW Iran)

Fault interaction creates areas of local concentration of stress and disturbances that affect the geometry and cognitive movement of faults. This stress concentration can create secondary structures in damage. In this article, the influence of the interaction or relationships between the Zagros and Arabian faults in the Zagros foreland on the formation and different geometry of the Rag Sefid and Tango anticlines is investigated and explained.

Due to the occurrence of the phenomenon of fault interaction between the faults that cause the Rag Sefid and Tengo anticlines, the three-dimensional interaction theoretical models between the fault segments are first introduced. By comparing the geometrical condition of fault parts in the study area with theoretical models, the types of fault interaction in this area are introduced. Finally, due to the dependence of the folds in the region on the fault, and with a detailed study of the geometry and dimensions of the underlying faults, the factors affecting changes in the pattern of folds are examined and the development of folds with different geometries, dimensions, extensions and mechanisms is justified.

Regarding the length more than 3 times of the Rag Sefid fault respect to the southern part of the Hendijan-Izeh strike-slip fault, the mean slope of 47 degrees of the Rag Sefid fault relative to the Hendijan-Izeh fault of 80 degrees and according to the general compression direction of N22E in the Southwest of Iran and the southern part of the Hendjan-Izeh fault trend (N20E), as well as the Rag Sefid fault trend, which is approximately perpendicular to the general compression direction, the deformation amount of the Rag Sefid fault is more than the Hendijan fault. In this condition, the stress field of the Rag Sefid thrust fault is dominated and due to the less resistance of the rising, folding with a larger amplitude occurs on the the Rag Sefid anticline; so that the folding amplitude in the Rag Sefid anticline is more than twice as large as the Tango anticline, and the tip of the Tango anticline is about 1,200 meters lower than the Rag Sefid anticline.

It can be concluded that in a set of faults where the interaction between the faults has occurred, larger, shallower faults with a plane slope of about 45 degrees, which have a diagonal or vertical orientation compared to the general orientation, they can create large and clearer folds similar to the folds with large dimensions in the Rag Sefid anticline compared to the Tango anticline.