Structures of the Kirkuk Embayment, Northern Iraq; Foreland Structures Or Zagros Fold Belt Structures?

Abstract

Several anticlines in northern Iraq and Syria have been studied through the construction of balanced and restored cross sections. Based upon structural analysis each of the studied anticlines is a faultpropagation fold that developed due to Zagros related recent inversion of much older normal faults. Studies on the Iranian part of the Zagros fold belt have suggested that the regional variation in the character of the fold belt is related to weak detachment surfaces in the stratigraphic section, primarily the decollement developed near the top of the Hormuz salt where the salt is present. No evidence for Hormuz salt has been found within the Kirkuk Embayment, and although detachment surfaces contribute the area’s structural character, the prominent folds appear to originate mainly from basement involved faults. Two distinct inversion structural trends exist; an EW system and a NW system of inverted grabens. In Syria, several of the faults associated with the EW trending system cuts the basement on seismic data and have stratigraphic relationships suggesting that their displacement originated in the Neoproterozoic. In Iraq where a thicker sedimentary section is present, the available seismic data does not show the complete sedimentary section or fault systems’ trajectories. While the NW fault system of inverted normal faults could be linked to the Zagros Orogen by a decollement surface in the sedimentary section, regional relationships and potential-field data suggest that this trend also is basement involved and has a Neoproterozoic origin.