Stratigraphy and Palaeontology
Mohammad Sharifi; Ebrahim Ghasemi-Nejad; M. Akhtari; Mehdi Sarfi; Mohsen Yazdi-Moghadam
Abstract
The Bazyab Formation is one of the Cretaceous rock units in the Khor and Byabanak area. In this study we investigated palynological content of the Bazyab Formation at the Bazyab stratigraphic section where it is up to 1067 meters thick and consists of marlstones, shales, sandstones, limestones and sandy ...
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The Bazyab Formation is one of the Cretaceous rock units in the Khor and Byabanak area. In this study we investigated palynological content of the Bazyab Formation at the Bazyab stratigraphic section where it is up to 1067 meters thick and consists of marlstones, shales, sandstones, limestones and sandy limestones, claystone, shale and interlayers of limestone. The formation at this section is confined conformably between Shah-Kuh Formation at the base and Debarsu Formation at the top. A total of 40 rock samples have been collected from the formation and investigated for their palynological contents. The obtained palynological data resulted in detection of twenty-nine genera and54 species of marine dinocysts alongside with 20 genera and 29 species of terrestrial palynomorphs (spores and pollens). An age of Aptian –Albian is constrained for the formation in this section on the evidence of recorded palynomorphs. Based on high frequencyof inner neritic dinocysts, planktonic foraminifers and mudstone and wackestone facies of the carbonate beds, an inner shelf sedimentary environment was suggested as the depositional environment of the Bazyab Formation.
M Allameh; B Torabian
Abstract
Farrokhi Formation is a Cretaceous rock unit in Central Iran that lithologically contains lime, marl and marly lime accompanied by layers of fossiliferous limestones. This formation lays conformably over the Haft-Tuman Formation, while its upper boundary is disconformable with Chupanan Formation. In ...
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Farrokhi Formation is a Cretaceous rock unit in Central Iran that lithologically contains lime, marl and marly lime accompanied by layers of fossiliferous limestones. This formation lays conformably over the Haft-Tuman Formation, while its upper boundary is disconformable with Chupanan Formation. In this study, 23 rock samples from marl segment of the Farokhi Formation were prepared palynologically and their various palynological constituents were characterized and quantified by percent. Assessing the organic elements of formation demonstrated fair preservation of organic matters in marl segments and allowed determination of the sedimentation rate and oxygen content. Palynofacies investigation signifies that marl segment has been deposited in shallow to open marine environment with medium energy, and one palynofacies has been diagnosed for it. According to typical dinoflagellate cysts, a warm and rather shallow environment with medium energy and variable salinity is suggested for the period of sedimentation of the marl segment.
Sh. Nouri; E. Ghaseminejad; M. R. Majidifard
Abstract
The Sanganeh Formation is one of the Early Cretaceous rock units in the Koppeh- Dagh basin. This formation in the Dahaneh Gholaman section (in north of Bojnord city) with a thickness of 900 meters (consist of marl, shale and limestone) is laying conformably on the Sarcheshmeh Formation and covered by ...
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The Sanganeh Formation is one of the Early Cretaceous rock units in the Koppeh- Dagh basin. This formation in the Dahaneh Gholaman section (in north of Bojnord city) with a thickness of 900 meters (consist of marl, shale and limestone) is laying conformably on the Sarcheshmeh Formation and covered by Atamir Formation. In this study, biostratigraphic investigations on 50 palynological samples from the Sanganeh Formation led to recognition of 21 genera and 31 species of dinoflagellate cysts indicating an age of Late Aptian-Albian belonging to Odontochitina operculata zone. Also palynofacies studies revealed two types of palynofacies (II and IV). Palynofacies studies show dominance of palynofacies II through the stratigraphic column indicating a marginal dysoxic-anoxic basin. On the other hand, presence of palynofacies IV in some parts along the stratigraphic column reflects increase in the depth of the marine environment from time to time.
F Yousefi Moghadam; M Allameh; S.M Hosseininezhad; L Bakhshandeh
Abstract
Ab-deraz Formation is one of the Lithostratigraphic units of upper cretaceous the age of which is determined as touronian-santonian in Kopet-Dagh sedimentary basin located in northeast Iran. Its major lithology in Sanganeh section contains Marl, Marly limestone, and gray shales and light green shale ...
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Ab-deraz Formation is one of the Lithostratigraphic units of upper cretaceous the age of which is determined as touronian-santonian in Kopet-Dagh sedimentary basin located in northeast Iran. Its major lithology in Sanganeh section contains Marl, Marly limestone, and gray shales and light green shale along with three band of chalky limestones. This Formation thickness in Sanganeh section is measured as 530 meter out of which 41 samples were systematically taken. In order to interpret the Paleoenvironment and Sequence stratigraphy, this Formation in Sanganeh section was analyzed by using palynological facies and conformity of Osracodas and Dinoflagellates. Having examined the frequency ratio (abundance) of two groups of Ostracoda (Platycopids to Podocopids), it was observed that the most abundant oceanic dissolved oxygen is seen in Marly layers near Calcareous band of chalky limestones and the least abundant is seen in layers far from those bands. In addition, based on the abundance of Genus, such as Paracypris, Brachycthere, and Bairdia mostly seen near Calcareous band of chalky limestones and Ostracoda with ornamented Carapce and thicker layers such as Veenia, Pterygocythereis seen in Marly layers near chalky limestones, it can be stated that it is shallower near Calcareous band of chalky limestones and moving toward Marly and shale layers, it becomes deeper. Analyzing 82 Palynological slides resulted in identification of three Palynofaies of V, IV, II, in this Formation. The results obtained from statistical studies of palynological factors including AOM to Marine palynomorph ratio, abundance of Foraminifera test lining, and peridinioid/Gonyaulacoid ratio for determining the amount of oxygen in the environment indicate that often there were low levels of oxygen in this Formation, however, there were times when oxic condition was dominant. Also in order to Relative sea level changes by Palynological facies, two factors were used first one being dinocysts of specific inner neritic to outer neritic ratio and chorate/ proximate, proximochorate and cavate cysts (C/PPC) ratio. Studies in which Ostracoda were used confirm the results obtained from palynological studies and show that sediments of Ab-deraz Formation are deposited on each other in an open marine and change from Inner neritic to outer neritic in disoxic to suboxic environment.
M Allameh; S Saadati Jafarabadi
Abstract
The Dalichai Formation is among marine deposits in Jurrasic period that has a geographic expansion in north of Iran. In order to palynological studies in eastern part of the BinaloudMountains an outcrop of this formation, in the bar village was selected. The thickness in bar village section is 255 meters ...
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The Dalichai Formation is among marine deposits in Jurrasic period that has a geographic expansion in north of Iran. In order to palynological studies in eastern part of the BinaloudMountains an outcrop of this formation, in the bar village was selected. The thickness in bar village section is 255 meters includes dark gray shales. The study of 112 slides of 28 samples taken from this formation showed that the most of the samples contain palynomorphs specifically dinoflagellates. 53 species belonging to 27 genera of dinoflagellates were identified. According to dinoflagellates, a middle Jurassic age was determined for the Dalichai Formation in the Bar village section. Based on the study of three main groups of phytoclasts, marine palynomorphs and amorphic organic matters and result of the statistical studies of different factors, sedimentary environment of the Dalichai Formation in studied section was open marine basin with shallow and low oxygen condition.
