M Shafiee Ardestani; M Vahidinia; A Sadeghi
Abstract
In this research, we documented a paleontological study on the basis of planktic foraminifera, in five stratigraphic sections (Type, Padeha village, Shorab, Abderaz village and Qarehso) across the Santonian-Campanian transitional boundary in the eastern Kopeh-Dagh sedimentary basin. In all sections, ...
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In this research, we documented a paleontological study on the basis of planktic foraminifera, in five stratigraphic sections (Type, Padeha village, Shorab, Abderaz village and Qarehso) across the Santonian-Campanian transitional boundary in the eastern Kopeh-Dagh sedimentary basin. In all sections, no M. testudinarius Schlotheim (cosmopolitan species) was identified, which its last occurrence datum (LOD) is widely used to define the base of the Campanian stage. Several planktic foraminiferal biohorizons close to the Santonian/Campanian boundary were recorded, including the LOD’s of Ventilabrella austiniana Cushman, Dicarinella concavata (Brotzen) and Dicarinella asymetrica (Sigal), and the first occurrence datum (FOD) of Contusotruncana patelliformis (Gandolfi). The Santonian/Campanian boundary was placed in the upper part of the Dicarinella asymetrica Total Range Zone at the top of the Abderaz Formation in the type section and other sections in Shorab, Abderaz village, Padeha village, and at the base of the Abtalkh Formation in the Qarehso section. The acquired bio-models for the study sections are quite comparable with that of Gale et al, 2008 in WDS section, North Texas. On the basis of quantitative analysis of the planktic and benthic foraminiferal assemblages, the sparse presence of keeled planktic foraminifera and planktic foraminifera (%P) indicates that a shallow marine condition was prevailing just above the Santonian/Campanian boundary in the type section, Shorab, Abderaz and Padeha village sections. In addition, the abundance of such foraminifera (keeled planktic foraminifera and planktic foraminifera) reflects deeper water depths in the Qarehso section at the same time. Besides, estimation of the planktic to benthic ratio, which is based on the Van der Zwaan equilibrium, confirms that in the base of Campanian at one of the study sections (Qarehso section) the water depth was 160 m.
F Foroughi; A Lotfali Kani; S Gardin; M Vahidinia
Abstract
The Kopet-Dagh basin is located in the northeast of Iran, in the triangle border of Iran, Turkmenistan and Afghanistan and consists of the marine Jurassic to Neogene strata. The Abtalkh Formation is one of the thickest lithostratigraphic upper Cretaceous units in the eastern Kopet-Dagh basin and is composed ...
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The Kopet-Dagh basin is located in the northeast of Iran, in the triangle border of Iran, Turkmenistan and Afghanistan and consists of the marine Jurassic to Neogene strata. The Abtalkh Formation is one of the thickest lithostratigraphic upper Cretaceous units in the eastern Kopet-Dagh basin and is composed of light gray, green to bluish marl and silty marl. The Abtalkh Formation conformably overlies the Abderaz Formation, which contains marls and chalky limestones and is conformably overlain by the Nayzar Formation, which consists of sandstone, silty marl and limestone. The Abtalkh Formation contains very aboundant, rich and good to moderately preserved calcareous nannofossil assemblages of Tethyan realm. The total 220 samples in the jalilabad and 467 samples in the AbtalkhVillage stratigraphic sections, representing the oldest and youngest strata of upper Abderaz, Abtalkh and base of Nayzar successions, were collected. The thickness of Abtalkh Formation in the Jalilabad stratigraphic section is 1325.8m and for the AbtalkhVillage stratigraphic section is 1765m. One hundred sixteen nannoplanktonic species belonging to forty three genera and fifteen families were identified. The biostratigraphic study allowed the recognition of the calcareous nannofossil biozones of Sissingh (1977) emended by Perch-Nielsen (1985) and Burnett (1998). From bottom to top, part of CC19, CC20, CC21, CC22, part of CC23a biozones and UC14dTP, UC15bTP, UC15cTP, UC15dTP subzones and UC16 biozone were identified in the Jalilabad section. The Abtalkh Village section in the middle of eastern Kopet-Dagh basin is started with CC20 (UC15bTP) biozone and continued to CC23a (UC16) biozone. Nearly more than 30 calcareous nannofossil species were reported for the first time in Iran. The results of this study indicated that the age of Abtalkh Formation spans from early to uppermost Late Campanian for these two sections in the Kopet-Dagh basin.
A. R. Ashouri; M. R. Majidifard; M. Vahidinia; A. Raoufian
Abstract
A thick succession of Middle – Late Jurassic rocks in the western part of BinaludRange has been studied. This succession consists mainly of limestone, marly limestone and marl. The thickness of the succession in the study section (Baghi, north of Neyshabour) is 709 meters and is subdivided into ...
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A thick succession of Middle – Late Jurassic rocks in the western part of BinaludRange has been studied. This succession consists mainly of limestone, marly limestone and marl. The thickness of the succession in the study section (Baghi, north of Neyshabour) is 709 meters and is subdivided into 4 members. The lower boundary with the underlying dark shale and upper boundary with the overlying buff limestone are inconspicuous and transitional. Ammonites are the most important and abundant macrofossils in this section. 43 genera and 76 species have been identified among them 8 species are reported for the first time from Iran. Based on the ammonite fauna, Early Bathonian to Kimmeridjian ages are purposed for these rocks. The fauna show close relationship to Sub- Mediterranean province and there is a great similarity between ammonite fauna of the investigated area with Kope – Dagh and AlborzRange.
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.
