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.
N. Kharazizadeh; M. Almasian; Sh. Sherkati
Abstract
Geometric style and deformation analysis of folding are two important aims of geological studies in Zagros, which is related to concentration of considerable of hydrocarbon reservoirs in anticlinal traps of the belt. In this study, evolution and geometry of Aghajari subsurface anticline (Dezful embayment) ...
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Geometric style and deformation analysis of folding are two important aims of geological studies in Zagros, which is related to concentration of considerable of hydrocarbon reservoirs in anticlinal traps of the belt. In this study, evolution and geometry of Aghajari subsurface anticline (Dezful embayment) is considered based on 3D seismic data and well information. Based on illustrated structural cross sections, special attention was paid to geometrical variations of folding from fold pericline to central part of this structure. Geometrical complexity along and normal to the fold axis is related to implication of intermediate soft units in sedimentary pile. Fold evolution analysis shows limb rotation and hing migration which are the main mechanism for fold growth and passing from box to chevron style as well. Development of satellite structure around main anticlines in Zagros is promising features for hydrocarbon entrapment, which related to involment of decollement levels in folding.
