Influence of thrust and basement strike-slip faults on the geometry of the Amiran anticline structure in Lurestan subzone, West Zagros

The Amiran anticline with about 50 km length is located in NW-SE of the Zagros fold and thrust belt and the Lurestan sub-zone. The aim of this study was to investigate the role of thrust and basement strike-slip faults on the structural geometry of this anticline. For this purpose, three cross-section perpendicular to the anticline axis have been constructed in the NW, central, and SE parts of the anticline. A basement thrust fault in the southwestern limb of this anticline and two upper (Amiran Formation) and Middle (Garau Formation) detachment levels affect the folding geometry and led to the formation of disharmonic folding. In addition to the thrust fault at the southern limb, an N-S basement strike-slip fault in the middle part of the anticline has shifted the anticline axis from N50W in the southeast to N65W in the northwest. The disharmony of fold axis across the surface and deep structures and migration of the southern limb of the anticline is due to the effect of the basement structures on structural geometry of the study area. Therefore, basement strike-slip faults propagate to the inner parts of the fold-thrust belt in the Lurestan sub-zone and cause deformation of surface and deep anticlines.