Tectonics
Esmail Farahzadi; Seyed Ahmad Alavi; Mohammad Reza Ghassemi; Shahram Sherkati
Abstract
AbstractUnderstanding the history of uplift and folding in an area helps inferring the history of hydrocarbon genesis,migration and trapping and reducing exploratory drilling risks.Thermal model along with structural cross sections help understanding of this history and future plannings for ...
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AbstractUnderstanding the history of uplift and folding in an area helps inferring the history of hydrocarbon genesis,migration and trapping and reducing exploratory drilling risks.Thermal model along with structural cross sections help understanding of this history and future plannings for new exploration. In this paper we have used 3Dseismic reflective lines and geological maps to construct a regional balanced cross section and restore it in several stages. Combining of this cross section and a thermal model produced using vitrinite reflectance and apatite fission track, the history of exhumation and regional erosion is evaluated. Based on the results,unlike the Hormuz Series,the thickness of the Paleozoic sequence is equal throughout the region. This shows that the sedimentary-tectonic events have been the same in this period. The apatite fission track data indicate that the average time of rocks cooling is between14and24 million years ago (Late Oligocene-Middle Miocene).Based on the burial history graph, exhumation rate of the basement decrease from High Zagros to Abadan plain that show the basement in the northern part is involved in deformation earlier than in the southern part of the region. This involvement has affected the formation of structure,change of the sedimentary facies and the regional erosion pattern.
Tectonics
shima afkhami; Ahmad Alavi; Mohammad Reza Yamini; Mohamad Reza Ghasemi
Abstract
The main purpose of this study is to investigate and structureral analyzes of Sirri oil field by subsurface geophysical data. In order to Seismic interpretation from 3 seismic lines (LL3, LL4 and LL5) picked up by Iranian Offshore Oil Company and SIC-1 well Data was used. In addition to interpreting ...
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The main purpose of this study is to investigate and structureral analyzes of Sirri oil field by subsurface geophysical data. In order to Seismic interpretation from 3 seismic lines (LL3, LL4 and LL5) picked up by Iranian Offshore Oil Company and SIC-1 well Data was used. In addition to interpreting the geological horizons and understanding the stratigraphic-structural evolution of the region they have also been used. The study area is located in the south of Iran and in the Persian Gulf. In this study, the geological analysis of the area has been studied by two-dimensional seismic surveying method and petrophysical images (up to Darian Formation) and Petrel software. The results show that the rising of the salt dome related to the Hormuz series has affected the overlying Formations in these field, and has created a dome shaped state for most of the Formations. Rising of the salt and folding of the sediments eventually resulted in faulting of the sediments. During the study and measurement of the angle between the edges, it was found that 15.2% of the folds are open and 84.8% are of the soft folds.
Tectonics
Mehdi Tavakoli Yaraki; Seyyed Ahmad Alavi; Mohammad Reza Ghassemi; Iraj Abdollahie fard
Abstract
The significance of mechanical stratigraphy of rocks in kinematics of folds has long been of interest to structural geologists. Parameters such as sedimentary facies variations and thickness of incompetent layers play major role in activity of these layers as detachment horizons. The purpose of this ...
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The significance of mechanical stratigraphy of rocks in kinematics of folds has long been of interest to structural geologists. Parameters such as sedimentary facies variations and thickness of incompetent layers play major role in activity of these layers as detachment horizons. The purpose of this study is to investigate the role of mechanical stratigraphy on fold geometry in the Aghajari and Pazanan anticlines within the Dezful Embayment zone. For this purpose, we have used seismic profiles, stratigraphic data and petrophysical logs as well as the previous stratigraphic works in study area. Results show that the Garau Formation is the major intermediate detachment level in the Aghajari structure, and has a significant control on folding geometry of the competent sequences of the Fahliyan to Asmari Formations. The Dashtak Formation and other incompetent evaporatic Formations of Middle-Upper Jurassic also have been active in the Aghajari structure. In contrast, in most parts of the Pazanan structure, the Garau and the Jurassic Formations do not have appropriate mechanical properties to act as intermediate detachment levels due to their change into hemipelagic facies and limestone (Surmeh Formation) respectively. Based on the evidences, the facies change in the abovementioned Formations occurs between the Pazanan and Aghajari anticlines. It seems that activity of the Hendijan-Izeh paleo-high also has some control on facies of the Garau Formation. Based on geometric characteristics and a geometric conceptual model provided for development of these structures, the folding style of the anticlines is suggested as an asymmetric faulted detachment fold type.
M. R. Moshrefi far; A. Alavi; M. Mohajjel
Abstract
In this research, separation of paleostress phases in the central part of Dehshir fault is investigated based on the study of heterogeneous fault-slip data and their related slickenside lineations. These data are measured from the Certaceous (Taft limestone), ...
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In this research, separation of paleostress phases in the central part of Dehshir fault is investigated based on the study of heterogeneous fault-slip data and their related slickenside lineations. These data are measured from the Certaceous (Taft limestone), early Eocene (Kerman conglomerate) and Eocene (Volcanics) formations. The main criteria used here to identify sense of fault-slip are stratiographic separation, accretionary mineral steps, Riedel shears and tension gash. The existing faults in the region of investigated often show two NE and NW trend in which the latter is usually dominant. Based on the study of heterogeneous fault-slip data and their related slickenside lineations and using the multiple inverse method, at least two phases are expected. These phases show that the axis of maximum principal stress, σ1, is at NE trend and that of minimum principal stress,σ3, is at NW trend. The location of σ3 usually indicates that the strike-slip and reverse strike-slip faults mostly occur in the region. In addition, the shape of the stress ellipsoid is prolate in the region.
