ORIGINAL PAPER Clues to inferred different thrust-related fold models and thin-thick skinned tectonics within a single folded structure in Iraqi Zagros, Kurdistan region Hassan Ghazi KakAmeen Balaki 1 & Abdulla Amir Omar 1 Received: 21 October 2017 /Accepted: 17 May 2018 /Published online: 13 June 2018 # Saudi Society for Geosciences 2018 Abstract The Maqloub–BardaRash structure is situated at the Low Folded Zone within the NW of the Zagros fold-thrust belt in the Iraqi Kurdistan region. One of the main goals of this work is to reveal the variation in the fold architecture and fault shape with depth to build a plausible fold model, as well as to explain the kinematic evolution of the Maqloub–BardaRash structure. The middle part of the anticlinal hinge line of the studied structure shows deviation and anticlockwise rotation. This character is ascribed to the presence of a north-south trending left-lateral strike-slip fault. This fault is considered to be a deep-seated basement fault that likely caused segmentation of Maqloub–BardaRash structure into two parts: the northwestern Maqloub structure which exhibits a normal asymmetry and the southeastern BardaRash structure with a reverse asymmetry. The balanced cross sections based on the top of Middle Miocene Fatha Formation from the studied structures displays a maximum total horizontal shortening of 14% for the Maqloub structure and 9.89% for the BardaRash segment at the same stratigraphic level. Through the Maqloub section, the thrust-related shortening increases downsection, whereas the fold-related shortening increases upsection. Whereas along BardaRash section, the fold-related shortening smaller irregular variations at different stratigraphic levels are evidenced. The Maqloub segment is interpreted as a fault-propagation fold, but the BardaRash segment is interpreted as a faulted detachment fold based on the geometrical analysis of deformed models. Based on the resulting deformed geometries from the balanced cross sections, the propagation of the Maqloub segment is associated with the activation of an underlying basement fault, whereas the BardaRash segment is decoupled along the Triassic ductile sequence. The structural characterization of two different models of the fault-related deformation along the individual Maqloub–BardaRash folded structure will enhance accurate well position of the crestal reservoir. Keywords Maqloub–BardaRashstructure . Faultpropagationfold . Faulteddetachmentfolds . Balancedcross section . Thin skin . Thick skin Introduction The fault detachment fold model is closely analogous to the thrust propagation anticline, but it is a product of the transition in deformation pattern from detachment folding processes to progressive fault propagation folding (Mitra 2002; Mitra 2003). McClay (2004) presented a conceptual model based on Dobson (1991). This model exhibits three different fold de- formation models that developed at same detachment level with progressive evolution. Here, during progressive evolu- tion, with increasing fault displacement, the detachment fold changes to thrust propagation anticline, and ultimately to transported thrust propagation anticline. The prolific oil and gas fields that were discovered within the Iraqi Kurdistan region in the previous years motivated several investigations (e.g., Kent 2010; Reif et al. 2011; Bretis et al. 2011; Csontos et al. 2012; Reif et al. 2012; English et al. 2015; Awdal et al. 2016; Koshnaw et al. 2016). Since tectonic deformation and propagation of the oil and gas bearing structures in the northwestern Zagros fold- thrust belt (ZFTB) segment in Iraqi Kurdistan are not well * Hassan Ghazi KakAmeen Balaki Hassan.Kakameen@su.edu.krd Abdulla Amir Omar Abdulla.omar@su.edu.krd 1 Department of Geology, College of Science, Salahaddin University, Erbil, Kurdistan Region, Iraq Arabian Journal of Geosciences (2018) 11: 293 https://doi.org/10.1007/s12517-018-3605-4