Comparison of the Fold Shape Between Rocks of The Cretaceous and Tertiary Periods in The Chia Gara Anticline in Northeastern Iraq by Using Fourier Mathematical Analysis

Abstract

Analyses and comparsion of fold style in the Chia Gara anticline, which is located in the high folded zone of Iraq have done between the rocks of the late cretaceous (Bekhme Formation) and rocks of the paleogene (Pila-Spi Formation) using the harmonic analyses of Fourier's mathematical method.The study on two traverse showes a difference vertically and laterally in the fold style between the two formations despite the similarty exist in the lithology and competance.this revels that the fold being affacted and change the style in the Pela Spi Formation largerly developed than the shape in the Bekhme Formation.This indicate that the fold was great affacted by listric fault on the Pila Spi Formation than Bekhme Formation due to reactivation on reverse movement on that fault during the time of collision (continental -continental) between Arabian and Eurasian plates. This leads to the consideration of the influence of the fold by the listric basal faults, which led to a change in the deforming tectonic pattern of the folding process in the Chia Gara Anticline. As it turned out that the shape of the fold in the Pila Spi Formation is more developed than its counterpart in the Bekhme Formation, and this indicates that the fold was affected by a listric fault that affected the Pila Spi Formation to a greater degree than the Bekhme Formation, due to the reactivation of the fault in a reverse movement during the Eocene (i.e., the time of the continental-continental collision) between Arabian and Eurasian plates.