عنوان مقاله [English]
نویسندگان [English]چکیده [English]
The main purpose of this study is to analyze structural features in the Strait of Hormuz by using subsurface geophysical data. One of the main tasks is, therefore, to interpret 75 lines of the PC2000 seismic lines acquired by the Dutch and Norwegian Statoil company in the waters of the Persian Gulf and Oman Sea in 2000. In addition to interpreting the horizon, these data are used to understand the evolution of stratigraphic–structural history of this region. Situated in 55°–56° E longitude and 25°30'–27° N latitude, the study area is located in the south of Iran in the Strait of Hormuz which is known as Block E for the National Iranian Oil Company. The size of the Hormuz study area is in the order of 10000 km2. Within the area, there is one large island, Qeshm Island, and several smaller ones. Because the study area is a submarine, there is no possibility of direct examination of existing structures; therefore 2D seismic reflection data and submarine drilling data (8 wells) are used for modeling the subsurface structures and structural analysis in this area by Petrel software. Eight offshore wells were tied to the seismic data, providing the basis for the definition of horizons that varied in age from Early Cretaceous to Pliocene. The seismic data have been loaded to Petrel software in SEG-Y tape format. The SEG-Y format is generally accepted as a common format for both marine and land seismic data. The results have shown that in parts of the area, salt diapirism began after sedimentation of the Hormuz salt by downbuilding mechanism, and in other parts it has been affected by Mesozoic and Cenozoic reactivated basement faults coupled with buoyancy force. Two growth stages, active and passive, are known for diapiric structures. Also, the salt dome structures are related to some basement faults trending NE–SW, which provided a path for upward movement of salt. Most of these faults are concentrated in the eastern Hormuz Province where structural complexity is justified due to the effect of Oman and Zagros orogenies. The structuring as seen today is mainly the result of the Upper Cretaceous to Early Tertiary Oman Orogeny and the Late Miocene to Recent arrival of the southward advancing Zagros Orogeny. Most faults below the Intra-Mishan unconformity are thrust and reverse faults. The radial normal faults are predominant on top of the all diapirs. Radius of influence of individual diapirs is about twice of their diameter. Furthermore, folds are shorter and wider as compared to those in the north-western part of the Zagros, such that the wavelength is about 23 times of amplitude. The measurements carried out on the 39 interlimb angle folds reveals that 2/56 percent are open fold and 97/43 percent are gentle folds (50 percent have 140-160 interlimb angle, 34/21 percent have 160-180 interlimb angle and 15/78 percent have 120-140 interlimb angle).