Author(s)

K. H. Karim & S. H. Sulaiman

Abstract

In the Kurdistan part of the Zagros Fold-Thrust belt, as whole Zagros, many deformation types and scales are described which all have effects on oil accumulation and preservation. One of these deformations is lateral thrust which must be encountered during a search for oil in the area. At present, the lateral thrusts are described and analyzed for the first time in the area. The origin of the several lateral thrusts (oblique local thrust) are studied in Mawat area from Kurdistan Region of northeastern Iraq at about 30km to the north of Sulaimani city. The study is achieved in terms of the relation with both the Main Zagros Thrust Fault and the graben that exists in Chwarta-Mawat. These local thrusts are occurring in two groups, each group dips nearly 15º in opposite directions towards the northwest and southeast (about 340º and 155º respectively). The thrusts are associated with small reverse faults with nearly the same dip direction. These directions are nearly normal or oblique to dip direction of the Main Zagros Thrust Fault. The origin of these oblique thrusts is attributed to one of the following four possibilities: 1. Local thrusts may belong to the lateral boundaries of the Main Zagros Thrust Fault (MZTF). The lateral boundaries make up the lateral thrust of the main thrust fold thrust belts. Field evidence that aids this probability is that the Main Zagros Thrust Fault is located about 2km to the northeast of the location of the lateral thrusts. Other evidence is the angle of striations of the associated reverse faults surface which is about 15–20. These angles are close to the direction of the sigma one of the Main Zagros Thrust Fault which is about N38E degrees in the studied area. 2. The possibility is that these thrusts are generated by shortening associated with the graben that is bounded by two large normal faults which are mentioned in previous studies. The third possibly is that the thrusts are formed under the effect of two of the above factors which include horizontal stress of the local front of the main Zagros thrust and vertical stress

Keywords

lateral thrust, oblique thrust, Aqra Formation, Zagros Main thrust, Chwarta-Mawat area