The Role of Razak Fault in Controlling the Sedimentary Basin and Hydrocarbon Systems in External Fars Region, Zagros, Iran

Fars sub-basin is located in the Zagros fold-thrust belt and includes a large number of hydrocarbon reserves, especially gas. The existence of numerous basement faults and strike-slip in this region along with the uplift and depocenter of basement blocks has been considered effective factors in controlling sedimentary basins before, after, and synchronous with sedimentation. In this study, the role of the Razak fault basin in the external Fars area as an effective factor in controlling the sedimentary basin was evaluated. For this purpose, by providing isopach maps and 3D modeling from the basin floor at synsedimentary formations, the activity of the Razak fault along with its role in increasing or decreasing the hydrocarbon potential of the region and adjacent anticlines, was investigated. The results show that the inactivity of this fault at the sedimentation time of the Dalan, Gadvan, Darian, and Kazhdumi formations, while at the deposition time, the formations of Kangan, Dashtak, Hith, Fahlian, Laffan, Ilam, and Pabadeh remained active and controlled the sedimentation in the basin. Also, the uplift and depocenter of the basement blocks occurred to the Razak fault's performance, caused an increase in the hydrocarbon potential of the Dehram Group in the anticlines of Marz, Varavi, Tabnak, Dehnow, Khalfani, Chiru, and Madar. While the northeastern part of the study area and the anticlines of Bonashkatu, Pishvar, Bavush, Gavbast, and Gezzeh are less important. In addition, Khami and Bangestan reservoirs are also without hydrocarbon potential due to the Razak fault's performance.