F. Shirezade Esfahani; A. Bayet-Goll; N. Kohansal Ghadimvand; A. Kangazian; A. Akbari Mohammadi; M. Sadri
Abstract
The carbonate successions (Tournaisian-Visean) exposed in the Tang-e-Darchaleh and Banarizeh sections from Sanandaj-Sirjan Zone (SSZ), Iran, have been used to generate a facies model. From the analysis of facies and their associations, four depositional zones are recognized on the Tournaisian-Visean ...
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The carbonate successions (Tournaisian-Visean) exposed in the Tang-e-Darchaleh and Banarizeh sections from Sanandaj-Sirjan Zone (SSZ), Iran, have been used to generate a facies model. From the analysis of facies and their associations, four depositional zones are recognized on the Tournaisian-Visean ramp: basinal environments, outer ramp (FA1 and FA2; deep subtidal associations), mid ramp (FA3, FA4 and FA6; shallow subtidal to lower intetidal associations), and inner ramp (FA5; shoal). The gradual transitions between facies and facies associations, as well as the depositional profile of the shelf transect indicate a low gradient ramp. The observed sedimentary features in the facies associations portray a transgressive, proximal-to-distal, wave-dominated combined flow marine ramp sequence, as recorded in stratigraphic changes in character of storm bed sequences and the spatial arrangement of types of storm bed along the depth related environmental gradients. This study suggests that during the Lower Carboniferous, a broad shelfal platform covered the southern margin of the Palaeotethys, which was characterized by dominantly shallow carbonate ramp.
Stratigraphy and Palaeontology
Mohammad Lorstani; Abdolhosein kangazian; Amrolah Safari; M.R Noura
Abstract
In this study, the subsurface sedimentary successions of the Asmari Formation have been studied using cores and thin sections obtained from the well no. 28 of Haftkel and correlated with well no. 186 of Masjed-I-Soleiman oilfields data. in this study,18 carbonate and 1 carbonate/evaporate microfacies ...
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In this study, the subsurface sedimentary successions of the Asmari Formation have been studied using cores and thin sections obtained from the well no. 28 of Haftkel and correlated with well no. 186 of Masjed-I-Soleiman oilfields data. in this study,18 carbonate and 1 carbonate/evaporate microfacies and 2 noncarbonated microscopic facies were recognized. These microfacies and microscopic facies were grouped in 6 facies associations (include: Tidal Flat, Lagoon, Bar, Restricted marine, Open marine, and Mid ramp). Obtained facies associations, comparing them with standard facies models and statistical analyses, indicate that Asmari Formation was deposited in the inner and middle of a homoclinal carbonate ramp. Correlating Asmari association facies in Haftkel and Masjed-I-Soleiman oilfields showed that Haftkel oilfield has been in the shore-ward and Masjed-I-Soleiman oilfield has been in sea-ward of that ramp. Sequence stratigraphy studies express that the succession of Haftkel oilfield could be discriminated to six third order deposition sequences (Sq1- Sq6). Incorporation of the sequence stratigraphy criteria of Asmari successions in this oilfield with its previous biostratigraphy data reviles that Sq1 and Sq2 occurred during Aquitanian time and Sq3 to Sq6 during Burdigalian age. Correlating of Asmari sequences of this oilfield with the Asmari sequences of Masjed-I-Soleiman, based on cyclostratigraphy data, show the sequences of Masjed-I-Soleiman occurred in Burdigalian time. Also the correlation expresses the steep of proposed ramp was toward Masjed-I-Soleiman area. The sequence correlation with global sea level fluctuations shows Burdigalian depositional sequences occurred based on eustasy in these oilfields.
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.
F Shirezadeh Esfahani; N Kohansal Ghadimvand; A Kangazian; S.H Hejazi; V Hairapetian
Abstract
The Vazhnan Formation in the Shahreza-Abadeh belt, apparently extending from latest Carboniferous to Asselian, consists of conglomerate, limestone, sandstone and shale, which is correlative to the Dorud Formation of the Alborz Mountains and the Zaladou Formation of Central Iran. This work is presenting ...
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The Vazhnan Formation in the Shahreza-Abadeh belt, apparently extending from latest Carboniferous to Asselian, consists of conglomerate, limestone, sandstone and shale, which is correlative to the Dorud Formation of the Alborz Mountains and the Zaladou Formation of Central Iran. This work is presenting some results on revision of the lithostratigraphy of the Vazhnan Formation in the Tang-e-Darchaleh section (northeast of the Shahreza town). Introduction of this interval in the Banarizeh section (north of the Abadeh town) and correlation of the Vazhnan Formation in the sections understudied are other purposes. Based on the results of this study, Vazhnan Formation in the Tang-e-Darchaleh (as the type section) and Banarizeh (as the reference section) section is distinguished with the distinct eroded surface at the base and rests disconformably on the sandstones of Late Carboniferous, corresponding to the Sardar Formation. The upper part of this interval is disconformably overlain by the Surmaq Formation (late Early–Middle Permian) in the Banarizeh section. Field investigations revealed that the contact between the Vazhnan and Surmaq Formations in the Tang-e-Darchaleh section is faulted. The vertical and lateral changes of the lithofacies in the Vazhnan Formation indicate the depositional system which is evolved from a distal into a homoclinal ramp setting.
