GEOMETRY AND EVOLUTION OF FOLD STRUCTURES WITHIN THE HIGH FOLDED ZONE: ZAGROS FOLD-THRUST BELT, KURDISTAN REGION, IRAQ
Field data and publicly available seismic lines, as well as geomorphic interpretations of the landscape were used to understand the structure and the development of folds in the northern part of the Kirkuk Embayment. A range of geomorphic criteria were used to analyze the nature of the fold structures and categorize them into fault-bend or fault-propagation folds. Geomorphic criteria were also used to estimate the direction and magnitude of fold propagation. Lastly, cross-sections were constructed across two accessible transects in the region, with viable structures created down to the Triassic horizons.
Folds in the area are generally broad and box-shaped with close to gentle inter-limb angles and with wavelengths of 5-10km. Most structures fall in the class of fault-propagation folds, although some structures have characteristics transitional between fault-bend and fault-propagation folds. Folds have propagated laterally in sub-sections of the study area, and this growth appears to be constrained by the presence of basement faults, dominantly those in the NE-SW oriented Transverse system.
An improved understanding of the fold growth and the fold/thrust geometries will lead to improved predictions of trapping potential in individual structures in this frontier exploration area. Traps are likely to be segmented by the influence of basement faults and the influence of lateral propagation. In addition, geomorphological data hints at the involvement of reactivated basement faults (from the NW-SE trending Najd system) in the location and geometry of some structures.