Effects of Gachsaran Formation on Fold Style of Cover Sediments in Lali, Papileh and Ziloi Oil Fields Area, Zagros Fold-Thrust Belt


Department of Geology, Tarbiat Modares University


The study area is located in Dezful Embayment Zone of the Zagros Fold-Thrust Belt including the Lali, Papileh and Ziloi oil fields. Asmari Formation is the youngest reservoir rock of these oil fields and their cap rock is Gachsaran Formation. The Gachsaran Formation acts as detachment horizon and plays an important role in the folding style and structural evolution of the younger strata. Folding style has been identified in these strata using Jamison’s method. This formation decouples the structures at their top and beneath. In addition, its thickness variation from east to west causes a variation in fold wavelength and the number of surface faults. In this case, an increase in thickness makes a decrease in wavelength and the number of surface thrusts. The results of this study showed that analysis of structures developed on both overlaying and underlying strata of the Gachsaran Formation is important for exploration of hydrocarbon resources structures.


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