Stratigraphy and Palaeontology
Kamyar Younesi; Anoshiravan Lotfali Kani; Hormoz Ghalavand
Abstract
A conformable passage between Sarvak and Surgah Formations in Lurestan sedimentary basin reveals the potential of studying the Turonian–Coniacian boundary within Surgah Formation. Two sections of the Surgah Formation at Posht-e-Jangal and Pasan anticlines situated on the southeast of the Lurestan ...
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A conformable passage between Sarvak and Surgah Formations in Lurestan sedimentary basin reveals the potential of studying the Turonian–Coniacian boundary within Surgah Formation. Two sections of the Surgah Formation at Posht-e-Jangal and Pasan anticlines situated on the southeast of the Lurestan sedimentary basin have been studied on the basis calcareous nannofossils, and based on the observed distribution of nannoflora, the presence of CC12 to CC16 nannofossil biozones is documented which points to the latest Turonian to Coniacian age for the base of this Formation, while the top boundary is estimated approximately at earliest Santonian. Due to the absence of Micula staurophora, however, separation of CC13 and CC14 biozones is not possible and therefore, the Turonian–Coniacian boundary is placed somewhere within the said undivided interval. The FO of Calculites obscurus as the marker event for the top of CC16 biozone is not identified but on the basis of suspected LO of Lithastrinus septenarius as the marker event of the top of UC11 and onset of UC12, the record of early Santonian beds seems probable.
Stratigraphy and Palaeontology
Mohammad Hassan Shokri; Fatemeh Hadavi; Lida Khodadadi; M. Notghi Moghaddam; Hossein KAMYABI SHADAN
Abstract
Economically the Surgah Formation is the most significant in the Zagros sedimentary basin. In this study, the calcareous nannofossils have been investigated of the Surgah Formation from the Shah-nakhjir section. The thickness of the Surgah Formation is about 147 meters and composed of marly limestone ...
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Economically the Surgah Formation is the most significant in the Zagros sedimentary basin. In this study, the calcareous nannofossils have been investigated of the Surgah Formation from the Shah-nakhjir section. The thickness of the Surgah Formation is about 147 meters and composed of marly limestone deposits with diversity and well-preservation of calcareous nannofossil assemblages. In total, 41species belong to 22 genera were determinate and ultimately have compared with nannofossil standard zones. According to identified nannofossils, the age of the Middle Cenomanian- Middle Santonian corresponding to CC10- CC17 (Sissingh, 1977) includes Microrhabdulus decoratusZone (CC10), Quadrum gartneri Zone (CC11), Lucianorhabdus maleformis Zone (CC12), Marthasterites furcatus Zone (CC13), Micula decussataZone (CC14), Reinhardtites anthophorus Zone (CC15), Lucianorhabdus cayeuxii Zone (CC16), Calculites obscurus Zone (CC17) were suggested for the Surgah Formation in the studied section. Palaeoecological interpretations based on the identified species show warm climate and low depth conditions in low latitudes for deposits of the Surgah Formation in southwest of Ilam city (Shah-nakhjir section).
T Akbari; L Bakhshandeh
Abstract
Based on stratigraphic value of calcareous nannoplanktons in determing the age of sedimentary layers, they have been used for biostratigraphic studies of Surgah Formation in sadd Ilam (Ilam damp) section ,Kabir –Kuh of Ilam. This formation is composed mainly ot dark gray shales. In Type section ...
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Based on stratigraphic value of calcareous nannoplanktons in determing the age of sedimentary layers, they have been used for biostratigraphic studies of Surgah Formation in sadd Ilam (Ilam damp) section ,Kabir –Kuh of Ilam. This formation is composed mainly ot dark gray shales. In Type section , the thickness of the Surgah Formation is 153.7 m. 109 samples were taken from shaly layers and for the first time their calcareous nannofossils were studied.The result of taxonomic studies lead to identification of 16 family , 44 genera and 80 species. Based of first occurrence of the index species and the assemblages zones is nannofossil Zones CC13-CC15 or Uc 8- Uc 12 of standard pattern. Based on biozone,the Upper Cretaceous sediments in the study area are of the Turonian through Early Santonian ages.
A Sadeghi; M Raziani
Abstract
In order to study of the Surgah Formation in Southwest of Ilam City, one section in the Shah Nakhjir anticline was selected. The thickness of the Surgah Formation is about 161 meters and consists mainly of green shales and olive green marly shales with intercalation of gray shaly limestones. The lower ...
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In order to study of the Surgah Formation in Southwest of Ilam City, one section in the Shah Nakhjir anticline was selected. The thickness of the Surgah Formation is about 161 meters and consists mainly of green shales and olive green marly shales with intercalation of gray shaly limestones. The lower and upper boundaries of the Surgah Formation are the Sarvak and Ilam Formation, respectively and are conformable with sharp lithology and abundant iron nodules. In this study, 52 species belonging to 28 genuses of foraminifera and 3 biozones were identified. Based on the planktonic foraminifera and identified biozones, the Surgah Formation has an age of Late Turonian to early Late Santonian. Comparison of biozones identified in this section with those of the type section in Tang-e- Garab shows that these two sections are similar in biozones and age, and the only difference is in thickness of biozones.
S Azadbakht; M.R Majidifard; S.A Babazadeh
Abstract
In this study, the Surgah formation is identified and introduced for the first time in the east of Khoram-Abad. This formation in the east of Khoram-Abad consists of up to 260 meters light grey, thin to thick –bedded limestone with intercalation of shaly-limestone and a Turonian to Santonian age. ...
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In this study, the Surgah formation is identified and introduced for the first time in the east of Khoram-Abad. This formation in the east of Khoram-Abad consists of up to 260 meters light grey, thin to thick –bedded limestone with intercalation of shaly-limestone and a Turonian to Santonian age. In this section, the Surgah formation has continuous and conformable contacts with the lower Sarvak formation and the upper Ilam formation. In this study, 13 genera, 33 species and 3 biozones of the planktonic foraminifera have been recognized: Biozon I, Helvetoglobotruncanahelvetica-Clavihedbergella –Hedbergella Assemblage Zone indicating Turonian age, Biozon II, Marginotruncana sigali- Marginotruncana schneegansi Assemblage Zone indicating Coniacian age, and Biozone III, Globotruncana ventircosa -Dicarinella concavata Assemblage Zone showing Santonian age.
