Evaluation of hydrocarbon generation potential of turbidite shales of Amiran Formation in a surface-terrestrial section of Pusht-Jangal anticline, south of Lorestan using pyrolysis Rock-Eval 6

The Amiran Formation in the Zagros sedimentary basin has been accumulated with a considerable thickness in a deep sedimentary environment, where from the north of Lorestan to the south, fine-grained facies are dominant. In this research, the Amiran Formation was evaluated as a possible source rock from the point of view of organic geochemistry and hydrocarbon generation potential in this part of the Zagros sedimentary basin. In this goal, 20 samples of dark-colored shales of this formation were collected for Rock-Eval 6 analysis. Plotting the S2 values against the Toc of the samples indicates a weak to medium source rock and it ranks weak in terms of hydrocarbon generating power, The kerogen of this formation was found to be a combination of type III and type II, but type III kerogen is more abundant, which can be due to the dominance of continental facies that make up this formation. Plotting the Tmax values against HI showed that 75% of the samples are in the immature range and 25% of them are at the beginning of the oil generation window, or in other words, they have passed the thermal maturity by reaching the catagenesis stage, which is confirmed by Tmax between 435 and 460 degrees Celsius. The diagram of HI versus Toc indicates the formation of various organic facies in Amiran Formation, these facies include organic facies CD ,C ,BC . This variety of facies can be due to the variety of organic materials with marine and continental origin and sedimentation in deep environments .The Toc values of this formation are low due to the introduction of organic materials of continental origin (80% of the samples have Toc less than 1% by weight) and therefore the potential of the source rock has decreased.