Stratigraphy and Palaeontology
Arash shabanpour Haghighie; Lida Bakhshandeh; Tayebeh Mohtat; Masood Zamanipedram; Seyed hamid Vaziri
Abstract
In this research the Gurpi Formation in the Zagros Basin outcropping in the Dasht-e Arjan section, Shiraz province ,for the purpose of biozonational and Paleobathymetric studies were investigated. The thickness of these sediments is about 130 m and consists of Limestones and Shales.To determine the palaeobathymetry ...
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In this research the Gurpi Formation in the Zagros Basin outcropping in the Dasht-e Arjan section, Shiraz province ,for the purpose of biozonational and Paleobathymetric studies were investigated. The thickness of these sediments is about 130 m and consists of Limestones and Shales.To determine the palaeobathymetry of the Gurpi Formation, Planktonic and benthic foraminifera were investigated . A depth of about 270m to 510m was determined for these sediments based on the ratio of planktonic foraminifera to the total assemblages of foraminifera after omitting infaunal benthic foraminifera (%P*) by using the equation D = e (3.58718+(0.03534 × %P* )).In this study sixty-two species of planktonic foraminifera belonging to eighteen genera were recognised .According to the studied planktonic foraminifera the Upper Cretaceous deposits in this area were divided into nine biozones as following :biozone1- Dicarinella concavata Interval Zone. Biozone2- Dicarinella asymetrica Total Range Zone. Biozone3- Globotruncanita elevata Partial range zone .Biozone4- Globotruncana ventricosa Interval Zone. Biozone5- Radotruncana calcarata Interval zone. Biozone 6- Globotruncanella havanensis Partial Range Zone. Biozone7- Globotruncana aegyptiaca Interval Zone. Biozone 8- Gansserina gansseri Interval Zone. Biozone 9- Contusotruncana contusa Interval ZoneBased on the studied planktonic foraminifera the Early Santonian to Maastrichtian ages were determined for the sediments .
Stratigraphy and Palaeontology
Ghamarnaz Darabi; iraj Maghfouri Moghaddam; Abbas Sadeghi; Bizhan Yusefi
Abstract
In this study, biostratigraphy and Paleobathymetry of the Gurpi Formation in section southwest of Kuhdasht were studied. The thickness of Gurpi Formation in this section is 160 meters and its main lithology includes Marl, Limy Marl, Limestone and Shale. In this section Lower boundary of Gurpi Formation ...
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In this study, biostratigraphy and Paleobathymetry of the Gurpi Formation in section southwest of Kuhdasht were studied. The thickness of Gurpi Formation in this section is 160 meters and its main lithology includes Marl, Limy Marl, Limestone and Shale. In this section Lower boundary of Gurpi Formation is transition with Ilam Formation, and its upper boundary with Amiran Formation is unconformably. Here, on the basis of foraminiferal studies,50 species belonging to 24 genera of planktic foraminifera and Benthic were identified. Based on the stratigraphic distribution of the well known foraminifers, six foraminiferal biozones were established in the Gurpi Formation including: Globotruncana ventricosa Interval Zone, Radotruncana calcarata Taxon Range Zone, Globotruncanella havanensis Partial Range Zone, Globotruncana aegyptiaca Interval Zone, Gansserina gansseri Interval Zone, Contusotruncana contusa Interval Zone.The age of Gurpi Formation in this examined is determined based on identified biozones of Middel Campanian to Late Maastrichtian. A depth of 450 - 600 m was assigned for most parts of the sediments Gurpi Formatan was assigned ccording to planktic/epibenthic ratio and Percentage Morphotype 3 and the regression equation Depth = e (3.58718 + (0.03534 × %P*))
A Mahanipour; A Najafpour; M Dastanpour
Abstract
Calcareous nannofossils have been investigated at the lower part of the Gurpi Formation at the southwest of Gurpi anticline. According to the index calcareous nannofossils CC22/UC15eTP to CC24/UC18 bio-zones have been identified and the age of Late Campanian ‒ Early Maastrichtian is considered for ...
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Calcareous nannofossils have been investigated at the lower part of the Gurpi Formation at the southwest of Gurpi anticline. According to the index calcareous nannofossils CC22/UC15eTP to CC24/UC18 bio-zones have been identified and the age of Late Campanian ‒ Early Maastrichtian is considered for the studied interval. Statistical analysis of the assemblages indicate the presence of high and low nutrient taxa. The relative abundance of oligotrophic taxa (Watznaueria barnesae, Watznaueria fossacincta, Prediscosphaera spp., Eiffellithus spp., Lithraphidites carniolensis, Staurolithites spp., Micula staurophora, Cribrosphaerella ehrenbergii) is higher than eutrophic forms (Biscutum constans, Discorhabdus ignotus, Placozygus spiralis, Reinhardtites spp., Zeugrhabdotus spp., Tranolithus orionatus), and an increasing trend in the relative abundance of oligotrophic taxa along with a decreasing trend in the relative abundance of eutrophic forms can be observed towards the upper parts of the section (Campanian-Maastrichtian boundary and Early Maastrichtian).
H Seif; M Majidifard; T Mohtat
Abstract
The Farrokhi formation in 15 km southwest of Khur with a thickness of up to 117m consists of marl and limestone with Maastrichtian age. In this section, the Farrokhi formation disconformably overlies the Haftoman formation below and the Chupanan formation above. In the present study, 87 genera and 103 ...
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The Farrokhi formation in 15 km southwest of Khur with a thickness of up to 117m consists of marl and limestone with Maastrichtian age. In this section, the Farrokhi formation disconformably overlies the Haftoman formation below and the Chupanan formation above. In the present study, 87 genera and 103 species have been recognized. Based on foraminifera, the Farrokhi formation ranges from the Maastrichtian and 3 biozones in the rock unit 1 of the formation have been recognized: (1) Contusotruncana contuse Partial range zone (CF6), indexing Early Maastrichtian.(2) Pseudotextularia intermedia Partial range zone (CF5), index for late Early Maastrichtian index and (3) Racemiguembelin fructicosa Taxon Range Zone (CF4), an index for early Late maastrichtian. The Farrokhi formation can be subdivided into four rock units which are composed of marl and marly limestone. In addition, the Farrokhi formation fauna contains ostracods and high abundance of invertebrate as diverse species of brachiopods, echinoderms and bivalves with rare fragments of ammonites. The K/Pg boundary is in this section paraconform and can be compared with boundary of the Farrokhi and Chupanan formations. The evidence of paraconformity is a gap of Early Paleocene and changes in lithfacies. The Farrokhi formation is carbonate and it is parts of a carbonate system consisting of a platform and the adjacent slope.
N Badri; A.L Kani
Abstract
The Gurpi Formation has a wide extent in the Zagros Sedimentary Basin.It has received considerable attention due to its unique stratigraphic position, chronostratigraphic importance, and floral and faunal diversity and abundance.In order to biostratigraphically classification and correlation of theGurpi ...
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The Gurpi Formation has a wide extent in the Zagros Sedimentary Basin.It has received considerable attention due to its unique stratigraphic position, chronostratigraphic importance, and floral and faunal diversity and abundance.In order to biostratigraphically classification and correlation of theGurpi Formation in Kuh-e-Gach andKuh-e Kurdeh sections (Lar region, Fars province), this study concentrated on the calcareous nannofloral content of sediments.From the prepared 300 microscopic slides, a total of 53 species from 30 genera belonging to 15 families were determined, described and photographed. The distribution of nannofloral assemblage of the Gurpi Formation in Kuh-e Kurdeh reveals presence of CC18 to CC24 zones indicating an Early Campanian to Early Maastrichtian age, while in Kuh-e Gach CC19 to CC24 zones with an age range of Early Campanian to Early Maastrichtian are present. Occurrence of various speciesof low latitude affinities points toward such positioning of depositional basin of the Gurpi Formation.
B Ghasemshirazi; M.R Majidifard; A Kheradmand; T Mohtat
Abstract
In this research, the Campanian -Maastrichtian deposits in Jupar section, Central Iran have been studied to determine biozonation and Paleobathymetry of the deposits. The planktonic and benthic foraminifera were studied in order to assign palaeobathymetry of the Campanian- Maastrichtian deposits. A depth ...
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In this research, the Campanian -Maastrichtian deposits in Jupar section, Central Iran have been studied to determine biozonation and Paleobathymetry of the deposits. The planktonic and benthic foraminifera were studied in order to assign palaeobathymetry of the Campanian- Maastrichtian deposits. A depth of 490- 650 m was assigned for most parts of the sediments according to planktonic/epibenthic ratio and the regression equation D = e (3.58718+ (0.03534 × %P*)). In the present investigation, 58 planktonic species of 27 genera have been identified. The Campanian -Maastrichtian deposits is divided into 7 biozones on the basis of planktonic foraminifera, which are cosmopolitan and consist of biozone1-Globotruncanita elevata Partial Range Zone, Biozone2- Globotruncana ventricosa Interval Zone, Biozone3- Globotruncanita calcarata Interval Zone, Biozone4- Globotruncanella havanensis Partial range zone , Biozone5- Globotruncana aegyptiaca Interval zone, Biozone6- Gansserina gansseri Interval zone, and Biozone7- Contusotruncana contusa Interval Zone.
L. Bakhshandeh; A. Aghanabati; T. Mohtat
Abstract
The first studied Abtalkh Formation with Campanian – Maastrichtian age is well exposed in Kopeh Dagh area (Mozduran section). This formation conformably underlain carbonates of Abderaz Formation and overlain by Neyzar sandeston Formation, both formations have a gradual contact.
The second studied ...
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The first studied Abtalkh Formation with Campanian – Maastrichtian age is well exposed in Kopeh Dagh area (Mozduran section). This formation conformably underlain carbonates of Abderaz Formation and overlain by Neyzar sandeston Formation, both formations have a gradual contact.
The second studied formation so called Echinid marl formation of Santonian –Late Campanian age is exposed in Baharestan section, Central Iran, Esfehan area.
Based on 100 studied samples, there are litological and paleontological similarities between Abtalkh and Echinid marl formations. These evidences support strongly paleoecological and environmental similarities.
This ascertainment shows the close relation between the Kopeh Dagh and Central Iranbasins.
The fossil evidences found in both sections are as follow:
Globotruncana ventricosa (White), Globotruncanita elevata (Brotzen)
Globotruncana arca (Cushman), Globotruncanita stuartiformis (Dalbiez)
Globotruncana bulloides Volger, Globotruncana lapparenti Brotzen
Globotruncanita calcarata (Cushman), Globotruncana linneiana (d' Orbigny)
M. Vahidinia; A. Sadeghi; A. Shemirani; A-A. Aryai; M-A. Adabi
Abstract
The Kopet Dagh basin was formed during and after the collision of Turan plate with Iran plate before late Carnian (about 225 m.y. ago). It is located in the northeast of Iran and has a WNW to ESE trend. Neyzar Formation is composed of siliciclastic sediments and sandy shale and sandy limestone. This ...
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The Kopet Dagh basin was formed during and after the collision of Turan plate with Iran plate before late Carnian (about 225 m.y. ago). It is located in the northeast of Iran and has a WNW to ESE trend. Neyzar Formation is composed of siliciclastic sediments and sandy shale and sandy limestone. This unit is widespread in the east and northeast parts of the basin. To determine the stratigraphy, microfossils, microfacies and depositional environment of Neyzar Formation, three stratigraphic sections were selected and measurement and detailed sampling carried out on each of them. These sections from east to west are as fallows :
1) Tang-e Neyzar (Neyzar gorge) section
2) Tang-e Chahchaheh section
3) Jalil abad section
In the previous studies, the base and top boundaries of Neyzar Formation with Abtalkh and Kalat Formations were reported conformable and transitional (Afshar Harb, 1373). However, according to present investigations in eastern regions, lower boundary of Neyzar Formation with Abtalkh Formation in sections 1 and 2 are disconformable (as a Paleosol). This boundary in the section 3 is conformable and transitional. The upper boundary of Neyzar Formation with Kalat Formation in 1, 2 and 3 sections are disconformable (as a paleosoil).
Two types of facies were identified based on micropaleontologic and petrographic studies: 1) Siliciclastic facies, 2) Carbonate facies. Based on microfacies studies it seems that the siliciclastic parts of Neyzar Formation was deposited in a lagoonal-barrier island environments and the carbonaceous parts in a shallow carbonate platform (ramp type).
In most of the published reports and articles Neyzar Formation was introduced as low fossil bearing unit with no index–fossil. The age of this formation was determined only by the basis of its stratigraphical situation, but in the present investigation, in addition, 41 genera and 30 species of microfossils have been identified for the first time from index fossils such as:
Orbitoides apiculata, Orbitoides tissoti, Lepidorbitoides sp., Siderolites calcitrapoides, Pseudosiderolites vidali, Abathomphalus mayaroensis.
These fossil assemblages suggest the Maastrichtian, especially Late Maastrichtian age for Neyzar Formation.