Types of Folding in Some Anticlines from North of Iraq. A Critical Discussion

The Kurdistan Region of Iraq (KRI) is a mountainous territory that occupies the northern and northeastern parts of Iraq, which is a part of the Arabian Plate. The Arabian and Iranian plates are colliding with a convergent boundary. The collision has initiated anticlines with different shapes and types. Some of the anticlines are associated with thrust faults. The common orientation of the anticlines is northwest-southeast, changing westwards to E-W. To indicate the structural type of the developed anticlines, we have selected 60 anticlines in different parts of the central and northern parts of Iraq, including the Kurdistan Region. Using satellite images (Google Earth Pro), the length, hinge length, width, fold front sinuosity (FFS), and width of the shorter limb were measured. After that, we calculated the Aspect ratio (AR), Fold Symmetry Index (IFS or FSI), and Length of the Mountain Front (FS) of the anticlines. Consequently, we have indicated the structural type of those studied anticlines. Moreover, we didn’t recognize any difference in the type of anticlines in the three tectonic zones (Low Folded, High Folded, and Imbricate).
We also studied the lateral growth of the concerned anticlines based on geomorphological and structural forms and we have found that the majority of them exhibit lateral growth as indicated by the presence of the following form: en-echelon plunge (32 folds), Domes (38 folds), Abandoned alluvial fans (49 folds), Water gaps (35 folds), Wind gaps (29 folds), and Different valleys’ forms (60 folds). From the studied 60 anticlines, we have found that 34 folds are Detachment Folds, 15 are Asymmetric Detachment Folds, and 11 are Fault-Bend Folds. This means that the type of folds can be known without the help of seismic sections.