Tectonics
Mohammad R. Ghassemi; Ali Aghanabti; Abdollah Saeidi
Abstract
Correlation of the orogenic and epeirogenic events in Iran with the events that have been identified in different parts of the world and in different tectonic environments, has caused some confusion in the Iranian geological literature. After a brief review of the nature of known orogenic processes in ...
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Correlation of the orogenic and epeirogenic events in Iran with the events that have been identified in different parts of the world and in different tectonic environments, has caused some confusion in the Iranian geological literature. After a brief review of the nature of known orogenic processes in the world, examining issues related to the abovementioned correlations, and considering the tectonic history of various parts of Iran, we have tried to systematically describe and name the important orogenic and epeirogenic events of the country. Most Precambrian orogenic events in Iran are dubious due to unknown age and poorly constrained tectonic setting of the rock units attributed to Precambrian. Paleozoic in Iran has been mostly associated with epeirogenic events, and the only sign of a real orogenic event goes back to the Late Carboniferous in northern Iran. The important Mesozoic and Cenozoic orogenic events have shaped the modern tectonic configuration of Iran. The Paleotethys suture in northern and central Iran formed during the Gorgani orogeny, development of the Central Iranian active margin (Sanandaj-Sirjan) occurred in the Ekbatani orogeny, ophiolite obduction in Central Iran and Zagros developed during the Late Cretaceous events, and collision of the Iranian plate with the Helmand block resulted in the Sistani orogeny. The creation of the Zagros and Alborz Mountain ranges started from Oligocene and Miocene times, respectively, and the deformation due to their shortening continues to this day.
Stratigraphy and Palaeontology
Zeinab Manouchehri; Tayebeh Mohtat; Seyed Ali Aghanabati; Morteza Khalatbari Jafari; Fatemeh Vakil Baghmisheh
Abstract
The sediments are generally limestone and marl. The lower boundary with the loer red Formation is disconfomity and the upper boundary with the equivalent formatin of Bakhtiari Firmation is paraconformity. The total number of fossils found in this section is 69 species, 72 genera and 46 families. These ...
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The sediments are generally limestone and marl. The lower boundary with the loer red Formation is disconfomity and the upper boundary with the equivalent formatin of Bakhtiari Firmation is paraconformity. The total number of fossils found in this section is 69 species, 72 genera and 46 families. These sediments are formed in an open shelf and under the open sea and lagon environment. The variety and abundance of bentic foraminifer’s forms and the low presence of plagic forms testify to the shallow basin in this section, which is also confirmed by the study of other fossils. One of the Markable features of this section is the presence of Ammonia species, especially Ammonia parkinsonia. This section has a complete sequence of members of Qom Formation. This species are profe of shallow water and continental shelf for this carbonates. This section consist all of members of Qom Formation and based on identified foraminifera comparable to assemblage zone 1 & 2 introduced by Adams & Bourgeois (1967). These zones that inclod: 1-Borealis Melo Group- Meandropsin; 2- Miogypsinoides- Archaias- Valvulinid. Based on index foraminifer's species and their stratigraphic distribution the age of this section is Chatian- Burdigalian (Upper Oligocene-Lower Miocene)
Stratigraphy and Palaeontology
kiana kiarostami; Darioush Baghbani; Seyed Mohsen Aleali; Seyed Ali Aghanabati; Mohammad Parandavar
Abstract
Lithostratigraphy and biostratigraphy studies on the Sarvak Formation in type section (Tang- e Sarvak, Northwest of Behbahan) show that this Formation has 710 meter thicknesses that divided in to four lithostratigraphic units. The Sarvak Formation in type section rests on the Kazhdumi Formation conformably ...
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Lithostratigraphy and biostratigraphy studies on the Sarvak Formation in type section (Tang- e Sarvak, Northwest of Behbahan) show that this Formation has 710 meter thicknesses that divided in to four lithostratigraphic units. The Sarvak Formation in type section rests on the Kazhdumi Formation conformably with gradational contact (black shales and black argillaceous limestone) and under the Gurpi Formation with disconformity boundary. In this study 8 genus and 9 species of planktonic foraminifera and 34 genera and 33 species of benthic foraminifera have been reported. Four biozones based on (wynd, 1965) and two biozone based on) Premoli Silva and Verga 2004) have been reported as follow; Four biozones based on Wynd 1965: 1- Favusella washitensis range Zone # 23,2- '' Oligostegina'' facies # 26,3- Rudist debris # 24, 4- Nezzazata– Alveolinids Assemblage Zone # 25, Tow biozones based on Premoli Silva and Verga 2004: 1-Muricohedbergella planispira Zone, 2-Ticinella primula Zone. It can propose an Albian- Cenomanian age for Sarvak Formation based on these biozones and also it can recognize Albian-Cenomanian boundary on occurrence of Muricohedbergella planispira and Whiteinella sp. in lower part of this Formation.
Stratigraphy and Palaeontology
Somayeh Baharlouei Yancheshmeh; Ebrahim Ghasemi Nejad; Hossain Rahimpour-Bonab; Seyyed Ali Aghanabati
Abstract
Permo- Triassic subsurface section at Lavan 3 Well in Lavan Gas Field exhibits a 85 m-thick succession of limy dolostone and dolomitic limestone bearing anhydrite in the upper Dalan Formation, as well as a 154 m-thick succession of limy dolostone and dolostone with anhydrite ...
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Permo- Triassic subsurface section at Lavan 3 Well in Lavan Gas Field exhibits a 85 m-thick succession of limy dolostone and dolomitic limestone bearing anhydrite in the upper Dalan Formation, as well as a 154 m-thick succession of limy dolostone and dolostone with anhydrite intercalations in Kangan Formation. In the present study, 116 species belonging to 55 foraminifera genera were identified which were divided into two biozones, namely Charliella altineri- Paraglobivalvulina mira- Dagmarita chanackchiensis Assemblage zone (Dzhulfian in age) and Claraia aurita- Spirorbis phlyctaena Assemblage zone (Anisian in age). Nine primary microfacies were identified in the upper Dalan Formation, while, 13 microfacies were detected in Kangan Formation, together with different sub-environments (sabkha, tidal flat, lagoon, submarine ridge, and open marine) which were found to be deposited in a shallow marine carbonate platform in the form of a homoclinal ramp. Based on microfacies changes, aggradational, progradational and retrogradational stacking patterns of deposits and by conformation with the Gama-ray log, these strata could be divided into a couple of third-order sedimentary sequences for the upper Dalan Formation, as well as a couple of third-orders for the Kangan Formation, including two system tracts (TST and HST). On a global scale, the findings are comparable to the upper part of the Absaroka supersequence.
