الملخص

Structural analyses including fold geometry, Harmonic (Fourier) analysis, vertical investigation of fold style, thickness change test and joints analysis were carried on Shaikhan Anticline which is one of the Foreland Folds of Iraq. Geometrical analysis of five traverses revealed its asymmetry except the area of the second traverse which shows symmetrical form. It is verging towards the north except the area of the first one. The anticline axis changes its direction along the anticline. It trends east-southeast in the eastern part, swings towards the east-northeast and returns to the first direction in the west. These swings were caused by two sinistral strike-slip faults displacing oblige to the fold axis.Fourier analysis revealed that the fold has low developed shape at the plunges. It is of chevronic-sinusoidal shape. While it has high developed shape (Parabolic-semi Elliptical) at the central part, along the third traverse which influenced by the transpression of the strike-slip fault.The vertical investigation of fold style showed that the fold axis direction was constantly anticlockwise changing from the Late Eocene to Middle Miocene and rotated clockwise from the Middle to Late Miocene. This axis also has a specific direction difference, in the folded strata between the Gercus And the Pila Spi formations. This was considered as an indicator for the listric fault reactivation. The suture listric fault was forced the anticline to the northward vergence. Formation thickness changes confirm the presence of this fault revealing that the formations younger than the Gercus are thicker in the southern limb. This indicates that the suture listric fault is of normal type.