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.
L. Azad Shahraki; H. Rahimpour Bonab; M. Ranjbaran; A. Kangazian
Abstract
The Lower Cretaceous (Neocomian) carbonates of the Fahliyan Formation are considered as important reservoir rocks in the Zagros Basin. In this study, the sedimentary successions of this formation in Lar (620m thick) and Khami (517m thick) anticlines, located in the Izeh zone, were investigated to analyze ...
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The Lower Cretaceous (Neocomian) carbonates of the Fahliyan Formation are considered as important reservoir rocks in the Zagros Basin. In this study, the sedimentary successions of this formation in Lar (620m thick) and Khami (517m thick) anticlines, located in the Izeh zone, were investigated to analyze microfacies, depositional environment, and diagenetic phenomena. Based on petrographic studies, 16 microfacies related to five facies belts of tidal flat, lagoon, carbonate shoal, mid ramp and outer ramp were recognized. Grainstone microfacies were found more abundant in the Lar stratigraphic section than the Khami section. Lack of turbidite deposits and reefal facies, and transitional changing of the facies show that the Fahliyan Formation was deposited in a homoclinal carbonate ramp. Abundance of mud dominated facies and rarity of high energy facies (like shoal facies) show that the ramp was a leeward one. According to petrographic studies, the main diagenetic features of the carbonates were micritization, cementation, dissolution, neomorphism, compaction, fracturing, and dolomitization. Due to deposition in the photic zone and high sedimentation rate, the thickness of the Fahliyan Formation in both stratigraphic sections is considerable, but based on the drawn isopach map, the thickest succession of the formation is found in the Lar section. Therefore, the Lar area is considered as the depocenter of the Fahliyan Formation. Difference in the thickness of the Fahliyan successions of Lar and Khami, most probably, is caused by the syndepositional activity of the north-south trending basement faults (like Kazeroon fault) in the region. Also, difference in the quantity of the burial compaction of the carbonate successions (caused by facies and diagenetic differences) played a role in secondary (burial) thickness changes.
