Geochemistry and sedimentary environments of Permian deposits in Eastern-Central Iran (original) (raw)
Related papers
2011
Permian rocks in east-central Iran (Posht-e-Badam and Tabas blocks) belong to well-defined sequences in juxtaposed Early and Late Permian biogeographic provinces. The Lower Permian Khan Formation in the Kalmard area (Within the Posht-e-Badam block) is composed of cyclic sequences of thick compositionally and texturally mature sandstones and thin carbonates. The sequences reflect several nearshore microfacies, which constitute three major paleoenvironmental associations: tidal flat, lagoon, and shoal (open marine microfacies are missing or very rare). The carbonate rocks of the Lower through Upper Permian Jamal Formation in the Shotori and Shirgesht areas (within the Tabas block) are comprised of four microfacies indicative of tidal flat, lagoon, foreshore and open marine paleoenvironments. The Jamal Formation was deposited on a homoclinal carbonate ramp, which deepens to the north (Bagh-e-Vang section) and thins in southern locations (near the Jamal Formation type section). The Khan Formation succession is composed of secondand third-order cyclically siliciclastic and carbonate sequences. The Jamal carbonate is composed of second-and third-order shallowing-upward sequences. Both local tectonic activity and global eustacy may have controlled the cyclicity of the Khan and Jamal formations. , vol. 8, no.
Carbonates and Evaporites, 2019
The Permian Jamal Formation characterized as one of the most significant successions in the Central Iran basin and constitutes a thick section (as much as 180 m) of limestone, dolomitic limestone, and dolomite in southeastern Kharu village in Tang-e Sarve area. The facies analysis of Jamal Formation leads to the identification of 11 microfacies, which are attributable to shoal, lagoon, and tidal flat environments. Results from petrographic evidence as well as facies analysis demonstrate that the depositional environment of Jamal Formation in the studied area (Kharu village, East Tabas) exhibits the characteristics of a homoclinal carbonate ramp platform with the gentle slope. This platform is mainly composed of tidal flat, lagoon, and shoal sub-environments. According to facies frequency analysis, the lagoon environment accounts for the highest abundance of facies (48%), whereas tidal flat environment shows the least abundance (17%). Bioturbation, micritization, cementation, dolomitization, neomorphism, physical and chemical compaction, and fracturing are the most important diagenetic features.
Open Journal of Geology, 2015
Early Permian deposits in north of Kalmard region recognize with formal group of Khan; they have various features in the different place. This group includes four different formations from lower to the upper part: Chili, Sartakht and Hermez. These formations consist of carbonate rocks. Chili Formation has 104 m, thickness in Darin section and consists of limestone with intermediates of shale and marland sandstone. Lower boundary of this formation is disconformable with Gachal formation. The upper boundary is separated by unconformity from the upper part Sartakht formation according to the lithological characters and microscopic studies, cause identifications of beach, intertidal, open and semi-restricted lagoon, shoals and bar and open marine sub-environments for the Chili Formation. Vertical changes of microfacies and depth changes curve show much more thickness of shoals and bar microfacies, and little thickness of open and semi-restricted lagoon and open marine microfacies. Deposits of Chili Formation in Darin section deposited in the gentle gradient Homoclinal ramp in the south of Paleotethys Ocean. Two depositional sequences have been identified in this formation, based on recognized Fusulinid, show age of Sakmarian, which has adaptation with Lower Absaroka III.
A New Approach to Permian System in the Section of Gahkum Mountain (Zagros-Iran)
Open Journal of Geology
The deposits of Permian system in Kuh-e-Gahkum consist of 480 m clastic subdiffusion of Faraghan Formation and carbonates of Dalan Formation. In this section, the sediments of Faraghan Formation, which is gradationally overlain by Dalan formation, unconformably overlies Zakin Formation (Lower Carboniferous). In the upper part, Kangan Formation rests on the Permian deposits with an erosional and unconformable contact. Studying the microscopic thin sections led to the identification of 37 genera and 37 species of Foraminifera as well as 14 genera and 15 species of algae. According to the identified foraminifera in Faraghan and Dalan Formations, the age of the rock units in Permian system is assigned to Julfian-Asselian.
2020
Permian stratigraphic sequences are widely distributed throughout Iranian, making this one of the best locations in the world to study15 this geological time interval. Nevertheless, some units lack detailed biostratigraphic characterization which is essential for16 palaeogeographic reconstructions. This preliminary study comprises a palynological assessment of a Permian stratigraphic section17 cropping out in the Ajabshir area (SW Azerbaijan, NW Iran). The continuous and relatively well-exposed Ajabshir section comprises18 Unit 3 of the Dorud Formation and the Nesen and Ruteh formation In this area, the Dorud Formation starts with the Unit 319 unconformably overlying the Mila Formation, with its lower units missing. Unit 3 (48 m thick) is characterized by sandstones with20 siltstones and shale intercalations and an upward increase of limestones. The overlying Ruteh Formation (192 m thick) consists21 mainly of carbonates with scattered coarse sandstone intercalations and dolomitic li...
Open Journal of Geology, 2016
The current paper is focused on the facies, sedimentary environment and depositional cycles study of the Middle-Late Permian sediments in the South Fars Zireh Gas Field, the subsurface section of well ZH-A. Four hundred thin-sections obtained from cores and cuttings were examined under standard petrographic microscope. For this study research, Corel Draw X6, Corel Photo-Paint, DN2 Microscopy Image Processing System, Scope Photo, Autodesk Map, Geocalc and Auto Cad 2014 were utilized. Based on microfacies analysis and significant founa and flora, fourteen major facies in four facies associations comprising tidal flat (A), lagoon (B), shoal (C) and open marine (D) identified in the well ZH-A. This formation was deposited in inner part of a homoclinal ramp. Based on depositional cycles, seven main 3 rd order sequences were revealed in the Well ZH-A. The ooid grainstone facies with interparticle and oomoldic porosity has high reservoir potential. The diagenetic processes like dolomitization and dissolution have significant effect in the reservoir quality. Based on research results, a major framework can be weaved and used to correlate reservoir layering.
Reservoir facies controlling factors in the Upper Permian Dalan Formation, SW Iran
The Upper Permian Dalan Formation is an economically significant gas and condensate reservoir in the Fars region of southwest Iran. It is composed mainly of limestone and dolostone. Facies analyses, depositional environments and diagenetic processes of the Dalan Formation at eight drilled wells and reference section at the Surmeh anticline were studied. Field and petrographic studies combined with wireline well logs analyses and available seismic images resulted in recognition of various carbonate facies related to tidal flat, lagoon, shoal, basinal facies tracts, siliciclastic and evaporitic facies deposited on a carbonate ramp. Petrographic investigations and facies analyses of the Dalan Formation, led to the recognition of aragonite mineralogy and diagenetic environments of the Dalan Formation, which resulted in recognition of controlling factors of reservoir facies. Grainstone facies deposited on paleohighs have marine cements with isopachous and fibrous fabrics, which leaching of grains created porous intervals. On the other hand, grainstone facies deposited in places with lower palaeogeographic positions, not only show limited distribution but also have been affected much more by deep burial cements and diagenetic processes, which resulted in loosing their reservoir properties. This study suggests that paleohighs had played main role in the diagenetic sequences and reservoir facies distribution.