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.
Sedimentology
Gholamreza Hosseinyar; Reza Moussavi-Harami; Iraj Abdollahi fard; Asadollah Mahboubi; Hamidreza Mosaffa
Abstract
Identification of falling-stage system tracts (FSST) in sequence stratigraphy has important role in sequence boundary recognition and exploration researches. However, formation and preservation chance of its related facies in the fluvial successions is very low. This study pays to signs and evidence ...
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Identification of falling-stage system tracts (FSST) in sequence stratigraphy has important role in sequence boundary recognition and exploration researches. However, formation and preservation chance of its related facies in the fluvial successions is very low. This study pays to signs and evidence of identification of the FSST in sequence stratigraphy with an example from Lower Cretaceous fluvial Shurijeh Formation in the east Kopeh Dagh Basin. Integration of 3D seismic data with boreholes data from seven wells and four outcrop sections (Shurijeh Village, Anjeer-Bulagh, Mozduran Pass and Qorqoreh) used in this study. Results show that during Late Jurassic-Early Cretaceous marine regression fine-grained and hybrid carbonate-siliciclastic facies in the base of the Shurijeh Formation are belong to falling stage system tract. These facies deposited in low energy condition in flood plain and coastal plain, related to the shoreline trajectory. Based on seismic stratigraphic study, fluvial system tocks place and channels created in the basin, during sea/base level forced regression. Quantitative seismic geomorphological analyses indicate that existed channels were hydraulically as bypassing channels.