Field data in combination with interpretation of old seismic lines across the Pusht-e Kuh arc and northwest Dezful embayment in the Zagros fold belt allow the investigation of the geometry of folding at different structural levels. Folds in the Pusht-e Kuh arc are exposed along the upper part of the 7-km (4.34-mi)-thick Competent Group level, which is folded between the main detachment at or near the base of the cover sequence (lower Mobile Group) and the Gachsaran evaporites (upper Mobile Group). Intermediate detachment levels (Triassic Dashtak, middle Cretaceous Garau and Kazhdumi, Paleocene Amiran, and middle Miocene Kalhur formations) within the Competent Group control the geometry of anticlines at surface as well as their variations with depth.

The Kabir Kuh anticline is the largest and highest anticline in the Pusht-e Kuh arc and has been selected to construct a geometrical model to explore the variations of folding style with depth. Results from this anticline constituted a backbone for both a regional study to link the mechanical stratigraphy to the structure and to build up a conceptual model for folding that may apply to the Pusht-e Kuh arc as well as to the Dezful embayment tectonic domains. The Kabir Kuh anticline in its central part displays box fold geometry, characterized by a wide and rounded crestal domain, which is slightly tilted to the southwest. This geometry developed above an intermediate detachment at the level of 1.3-km (0.81-mi)-thick Triassic Dashtak evaporites within the Competent Group. Below this detachment, the geometry of the fold changes to more acute with a narrower crestal region. Although conjectural, we propose low-angle thrusting forming a tectonic wedge to accommodate shortening at the deepest part of the anticline (Paleozoic sequence). Subsidiary thrusts, related to fold tightening, may reactivate axial surfaces as well as local detachment levels to propitiate displacements of the crest of the anticline above its forelimb as inferred along the southeastern segment of the Kabir Kuh anticline.

A conceptual model of folding characterized by changes in fold geometry at depth is proposed. A significant outcome of this model is that anticlines in the Passive Group may be displaced, sometimes few kilometers, from anticlines in the Competent Group. In the same way, the internal mechanically weak layers of the Competent Group may form intermediate detachments that can produce a significant change in fold style with depth and displace the upper part of the structure shifting again the position of the anticline crests.

The uplifted Pusht-e Kuh arc is an excellent natural laboratory to investigate potential relationships among mechanical stratigraphy, tectonic structure, time of oil generation, and time of trap development. Fold and thrust geometries investigated in this study are directly applicable to petroleum exploration of recently awarded exploration areas within the Pusht-e Kuh arc and may apply to the rest of the Zagros fold belt.