Tectonics
Mojtaba Ershadinia; Saeed Madanipour; Ali Yassaghi
Abstract
Faraghun Mountains are located in the south eastern part of the Zagros orogen. Early Ordovician- Permian rock units are deepest stratigraphic units exposed in the central part of the Faraghun Mountains. High Zagros Fault (HZF) is the main structural feature bordering southern flank of these mountains. ...
Read More
Faraghun Mountains are located in the south eastern part of the Zagros orogen. Early Ordovician- Permian rock units are deepest stratigraphic units exposed in the central part of the Faraghun Mountains. High Zagros Fault (HZF) is the main structural feature bordering southern flank of these mountains. Here we combine detailed mapping, field based structural kinematic analysis and cross sections to reconstruct structural evolution of the Faraghun Mountains. Our new structural and stratigraphic analysis document three kinematically and geometrically different western, central and eastern segments for HZF in the Faraghun Mountains. Eastern and western segments of HZF, those are dipping northward, are connected together with Zakin Fault that dipping to south. Late Paleozoic successions have exposed in the hanging wall of Zakin Fault and central segment of HZF in a pop-up geometry. Stratigraphic records document prominent variation in late Cretaceous sequences including Gurpi Formation in the Hanging wall and footwall of the HZF in the Faraghun Mountains. Higher thickness and basal conglomeratic nature of Gurpi Formation in the hanging wall of HZF with respect to its footwall might reflect normal kinematics of the HZF during late Jurassic-early Cretaceous time. All the stratigraphic and structural evidence represent post late Cretaceous compression accompanied by late Cenozoic right lateral transpression in Faraghun Mountains at SE Zagros.
Tectonics
Mahnaz Sabahi; Ramazan Ramazani Omali; Masoumeh Kordi; Mohsen Dourandish
Abstract
In the past decade, several geophysical, geological and reservoir studies have been done on the Qom formation in the Yortesha field for injection and gas storage purposes. Qom formation in this field has a poor reservoir characteristic (low porosity and permeability); therefore the role of fractures ...
Read More
In the past decade, several geophysical, geological and reservoir studies have been done on the Qom formation in the Yortesha field for injection and gas storage purposes. Qom formation in this field has a poor reservoir characteristic (low porosity and permeability); therefore the role of fractures for increasing permeability and improving reservoir quality is very important. In the current study, fractures’ concentration and strike patterns of the Qom and Upper Red formations as the carbonate reservoir and cap rock, respectively, have been investigated and compared in the Yortesha anticline and its adjacent anticlines (Davazdah Emam and Morreh) using surface and subsurface investigations. In order to achieve this goal, desert data gathering methods, remote sensing, and image log analysis have been used. Subsurface studies and interpretation of FMS and EMI image logs determined that fractures have also a secondary strike of NE-SW in addition to strike of NW-SE. Based on the FMS image log interpretation of well No. 2, three subsurface fracture sets have been identified with the strikes of N55E, N65E, and N15W as well as using the EMI log of well No. 4 shows the two dominant strike of N10E and S45E. The total 1852 specified fractures in the out crops of the Morreh and Davazdah Emam surface anticlines can lead to rose diagrams that show four fracture sets with the strikes of N10E, N45E, N80E, and S45E.
Tectonics
Mohammad Moumeni Taromsari; Maryam Dehbozorgi; Reaza Nozaem; Ali Yassaghi
Abstract
Kalmard fault is considered as one of the fundamental faults in central Iran zone. The Ozbak Kuh mountains with a NE-SW strike are located in central Iran in the Kalmard fault zone. Hence, analyze the folds and faults in this deformed zone can aid in the understanding of structural evolution of this ...
Read More
Kalmard fault is considered as one of the fundamental faults in central Iran zone. The Ozbak Kuh mountains with a NE-SW strike are located in central Iran in the Kalmard fault zone. Hence, analyze the folds and faults in this deformed zone can aid in the understanding of structural evolution of this area in central Iran. In this study, field operations and geometric-kinematic analysis of folds and faults, also study of their structural evolution are integrated in order to provide a better understanding of the structural evolution of the Ozbak Kuh area. The results display that before Cretaceous period the Ozbak-Kuh area was influenced by a compressional regime with a prependicular trend with respect to the Kalmrad fault that it caused the formation of folds and faults paralell to folds axial plane trends, after that compressional regime changing to a dextral strike slip regime in Cenozoic in direction of NE- SW, all structures in the study area such as, faults, folds axial plain and other related structures were influenced by the aforementioned strike slip stress. Generally the geometric- kinematic pattern of faults in the study area regarding to the major and R, P, R', and X faults is kind of simple shear and contraction parallel to deformed zone. In this pattern the simple shear is dominant and compression is trivial component. The mechanism of the faults in the study area shows that the deformation of the Ozbak Kuh mountains is toward the final stages of simple shear. The multiple steps of deformation, simple shear movements and intensity of deformation in the study area caused that the strike of all structures is to be in direction of NE-SW that it is parallel to the main fault zone.
Tectonics
Ali Taghavy; Mahdi Najafi; Najmeh Etemad-Saeed; Mohammad Seddigh
Abstract
A synthesis of 2-D seismic interpretation, exploration well data and field survey permit us to decipher the structural evolution history in the front of Fars paleo-high area, located in SE Zagros fold-and-thrust belt. In the current study, a structural evolution model is proposed for the region, according ...
Read More
A synthesis of 2-D seismic interpretation, exploration well data and field survey permit us to decipher the structural evolution history in the front of Fars paleo-high area, located in SE Zagros fold-and-thrust belt. In the current study, a structural evolution model is proposed for the region, according to a sequential restoration, which was performed based on the growth stratal unit’s pattern, together with constant length and area assumptions. The result of the sequential restoration indicated that in the late Eocene time, Tanbak anticline incepted on the hangingwall of the inverted mountain front basement fault, as an out of sequence forced fold. Although, thin-skinned detachment folding initiated in the lower Miocene, shortening and amplification of anticlines did not accelarated until the late Miocene time, when thrust faults formed on the limb of growing anticlines while Dashtak middle detachment thickened in the fold crestal areas, likely due to an intensified regional shortening.
Tectonics
E. Haji; H. Safari
Abstract
The Saqqez-Baneh area, as a part of the NW Sanandaj-Sirjan zone, is selected for investigation of different deformation stages. In this research, firstly, the lithology of outcropped rock units and visible lineaments were mapped using remote sensing approach. Then, field surveys were carried out for ...
Read More
The Saqqez-Baneh area, as a part of the NW Sanandaj-Sirjan zone, is selected for investigation of different deformation stages. In this research, firstly, the lithology of outcropped rock units and visible lineaments were mapped using remote sensing approach. Then, field surveys were carried out for structural measurements, during which major and minor faults and shear zones (as ductile zones) were measured and mapped. These data were then entered to GIS environment as vector layers (and attributed descriptions), resulting in preparation of a structural map. The results of field surveys along with geometric and kinematic analyses show that the major faults together with their related fault orders formed a curved shape of structures, outcropped rock unit patterns and intrusive localities. Geometric and kinematic analyses demonstrated three stages of movement: with north-south (in ductile environment), northeast-southwest (in ductile to brittle environment) and east-west (in brittle environment). These three stages caused three stages of faulting with trends along N140-150, N70-80 and N10-20 directions, which can be attributed to three orogenic phases in Precambrian and/or late Triassic (Katangai and/or Cimmerian), Cretaceous (Laramide) and Neogene (late Alpine events such as Savian to Pasadenian).
