STRUCTURAL ANALYSIS FOR THE PLUNGE AREAS OF BEKHAIR, BRIFCA, DOHUK AND ZAWITA ANTICLINES NORTHERN IRAQ USING SEISMIC SECTIONS

Abstract

The study area is located in Dohuk Governorate; Northern Iraq. The aim of this study is to concentrates on the structural analysis in the plunge areas of Bekhair, Dohuk, Brifca and Zawita anticlines by using seismic sections. The four anticlines have NW – SE trend, which coincide with the main trend of the Zagros folds. Three seismic sections (DK-16, DK-20, and DK-22) were used to emphasize the structural analysis and recognize the faults caused by folds development and affected on the plunge areas of the four anticlines. The results showed that the main axis of Bekhair anticline exhibits two small plunges (northern and southern domes) with a syncline in between. The northern dome near Zawita village, is developed as a fault bend fold over northeast-wards dipping forethrust. The dome extends eastwards in form of structure A, which is also developed as a fault bend fold, and is named Deralosh anticline in this study. The southern dome near Besire village, is developed over a planner northeast-wards dipping forethrust (Bekhair Thrust) as a fault propagation fold with reverse displacement of about 225 m. The syncline between the two domes also plunges eastwards to connect with the axis of the major syncline and continues plunging eastward. This study shows that Zawita anticline is composed of two structures; (A) and (B) and is separated by a saddle area. Structure B, which is named Benarinke anticline, is developed over a northeast-wards dipping forethrust; as a fault propagation fold along reverse displacement of about 150 m. Banye small anticline (Baby structure) may exist in the northeast part of the study area. Brifca anticline is developed as a fault propagation fold over a main planner northeastern dipping forethrust that caused in over thrusting of the Pila Spi Formation over the Injana Formation of the adjacent syncline with horizontal displacement of about 750 m, whereas the northern limb is influenced by southwest dipping backthrust resulted in ~ 150 m reverse displacement. Based on the swing of the major syncline, a left lateral movement is detected on the western lateral ramp separated between Bekhair and Brifca anticlines, whereas a right lateral movement is represented by the other two extends in the eastern part of the study area. A structural geological map was drawn for the study area. This study also revealed that the anticline, which was believed as Zawita anticline by GEOSURV (1961), is composed of structure A (Deralosh anticline) and structure B (Benarinke anticline) separated by the saddle area.