Sedimentology
Mahshid Sarookhani; Mahboubeh Hosseini-Barzi; Ali Mobasheri
Abstract
The Qom Formation with Oligocene-Miocene age which is important due to its hydrocarbon reservoirs in some areas, is outcropped with a 330 meters thick mixed siliciclastic-carbonate sequence in Dastjerd area that uncomfortably overlain the Lower Red Formation and is conformably underlained by Upper Red ...
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The Qom Formation with Oligocene-Miocene age which is important due to its hydrocarbon reservoirs in some areas, is outcropped with a 330 meters thick mixed siliciclastic-carbonate sequence in Dastjerd area that uncomfortably overlain the Lower Red Formation and is conformably underlained by Upper Red Formation. In this study, the deposits were studied for petrography, microfacies and sedimentary environment, sea-level changes and mixing mechanism. Based on the frequency and distribution of the skeletal and other constituents of the carbonate deposits of Qom Formation in the studied section, six microfacies associated with three facies belt (open marine, shoal & lagoon) were identified related to a carbonate ramp. Mixing and hybridization of carbonate deposits of Qom Formation with different amounts of siliciclastic inputs in sand, silt size in through the thickness and laterally in the depositional basin of this sediments, is related to the tectonic activity and erosion of older rocks such as the Lower Red Formation and associated Paleogene volcanic rocks, deposited in the backarc basin of a subduction system. According to the microfacies analysis of the studied sediments, two cycles of sea level changes were recognized. The first cycle is associated with unstability of the basin floor and fluctuations in the relative sea-level, which leads to the deposition of a thick layer of sandstone regarded to the high tectonic activity and the second cycle is coincident with more stability of the basin which ultimately tends to a shallowing condition.
Stratigraphy and Palaeontology
Meysam Shafiee Ardestani; Mohammad Vahidinia
Abstract
Apertural protective structures of the planktonic foraminifera in the Abderaz Formation have been studied in order to determine seal level changes in 4 stratigraphical sections including: Abderaz village, Muzduran pass, Padeha village and Shorb . Lithological study of the Abderaz Formation shown that ...
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Apertural protective structures of the planktonic foraminifera in the Abderaz Formation have been studied in order to determine seal level changes in 4 stratigraphical sections including: Abderaz village, Muzduran pass, Padeha village and Shorb . Lithological study of the Abderaz Formation shown that Shorab section (east of the kopeh-Dagh basin) with 374 meters and Padeha village section with 602 meters represent minimum and maxiumum thickness, respectively. A total of 77 planktonic foraminifers species belonging to 19 genera, have been identified in studied sections. Eight Apertural protected plates have been recognized in the umbilical side of the distinguished planktonic foraminifera. Besides, 4 porticus structures (Simple lip, Tooth like-Porticus, Spiral Porticus, Imbricate Porticus) belonging to the morphotype 2 and 3, three Tegillum structures (Roll-type Tegillum, Strap-Shape Tegillum, Sheet like-Tegillum) belonging to the morphotype 3, and one Lip structure belonging to the morphotype 1, as well as their frequency have been recognized. Statistical analysis of protected structures of the umbilical area have been demonstrated that unlike to the imbricate porticus and sheet like Tegillum, the lip and simple lip structures show the highest frequency, indicating that the Abderaz Formation deposited in the relative shallow marine environment.
P Rezaee; R Zarezadeh
Abstract
Qeshm is the largest island of the Persian Gulf and is located at the southern end of the folded Zagros zone. The stratigraphic units of the QeshmIsland include the Hormoz series, Mishan formation, Aghajari formation and the Quaternary deposits. The Quaternary calcareous marine terraces are an important ...
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Qeshm is the largest island of the Persian Gulf and is located at the southern end of the folded Zagros zone. The stratigraphic units of the QeshmIsland include the Hormoz series, Mishan formation, Aghajari formation and the Quaternary deposits. The Quaternary calcareous marine terraces are an important part of the deposits and an relief index of sea level changes of the Quaternary period in the QeshmIsland. These terraces overly unconformably the older deposits, specially the Aghajari formation. The field and laboratories studies show that these sediments were developed mostly in different parts of an inner ramp comprising of supra-intra tidal, lagoon, and barrier. Application of the radiocarbonical method in different levels of these terraces revealed a Holocene-Pleistocene age. According to this age, an uplift rate of 0.22 mm/y can be estimated for this island, while the throw rate of the Persian Gulf level during the Quaternary is -0.125 mm/y.
G. Daneshian; S. A. Moallemi; A. A. Azad
Abstract
In this research, the Sarvak Formation and lower part of the Surgah Formation in Kabirkuh anticline, southeast Ilam with thickness of 897 m were studied. Prospect of changes in umbilical structures of planktonic foraminifera such as lip, ortico throughout of Albian to Turonian were investigated. The ...
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In this research, the Sarvak Formation and lower part of the Surgah Formation in Kabirkuh anticline, southeast Ilam with thickness of 897 m were studied. Prospect of changes in umbilical structures of planktonic foraminifera such as lip, ortico throughout of Albian to Turonian were investigated. The phylogenic trend shows that lip structure in primary morphogroups gradually replaced by ortico in more developed forms. The statistical analyses showed that the trend of the mentioned changes is comparable with increasing the water depth while a decrease in depth result in the development of lip in studied planktonic foraminifera. According to foraminifera and Oligosteginids, the age of examining succession is late Middle Albian to Late Turonian. The study of different type of morphotype groups in this section indicates that the fauna mostly belong to morphotypes number two and one, and then rarely number three. The studied morphotypes show that the main part of sedimentation carried out in relatively deep marine condition The results show that the Muricohedbergella frequency at lower and middle parts of the Sarvak Formation incompatible with the basin depth decrease that is specified with two decreasing peaks (sea regression). Also Favusella frequency in line with three increasing peaks (sea Transgression), and is a good index for showing the basin depth. In the final part of the sequence, the presence of Whiteinella to increase peaks which are compatible with the basin increasing depth and sea transgressive in studied section.