Stratigraphy and Palaeontology
Hamideh Noroozpour
Abstract
In this research the biostratigraphy and lithostratigraphy of the Talou section (northwest Damghan) have been studied based on brachiopods of Lower Carboniferous in Mobarak Formation. The 580 me thick Mobarak Formation in Talou section consists of dark gray limestone with intercalation of organic rich ...
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In this research the biostratigraphy and lithostratigraphy of the Talou section (northwest Damghan) have been studied based on brachiopods of Lower Carboniferous in Mobarak Formation. The 580 me thick Mobarak Formation in Talou section consists of dark gray limestone with intercalation of organic rich black shale. This formation in the studied area is conformably overlie on Jeirud Formation. Vermiculate limestone of Elika Formation overlies the Mobarak Formation with an erosional surface. In the studied interval 25 genera and 30 species of brachiopods were identified. 4 assemblage zones have been identified in the early Carboniferous.Biozone 1 (Early Tournaisian): this zone is characterized by the following indicator species community. Spinocarinifera nigra, Rugosochonetes cf. hardrensis (Phillips,1841), Rossirhynchus adamantinus, Shumardella sp., Cleiothyridina transversa., Rossirhynchusadamantinus, Shumardella sp.; Biozone 2 (Middle Tournaisian): Spirifermissouriensis, Spirifer attenuatus (Sowerby,1839), Spirifer cf. trigonalis (Martin, 1809), Athyrishibernica Syringothyriscospidata; Biozone 3 (Late Tournaisian): Tomiproductus elegantulus, Marginatia aff. burlingtonensis (Hall,1893), Leptagonia cf. regularis, Fusellatornacensis, Marginatiaburlingtonensis; Biozone of 4 (Early- Middle Visean): Buxtonia cf. praejuresanensis, Marginatia cf. kinghirica, Cleiothyridina cf. okensis (Grunt,1980). therefore, the age of Mobarak Formation in the Talou section, is Tournaisian to Middle Visean. The sedimentary environment of Brachiopods of the Mobarak Formation are lagoon, bar or reef and fore-reef.
N Kohansal-Ghadimvand; SH Gholipouri; M.R Majidifard
Abstract
The early carboniferous Mobarak Formation was studied in southern flank of Ayenehvarzan–Dalichai anticline, in Aru and Seyedabad sections, east of Tehran. The aim of this study is to determine microfacies, interpretation of depositional environments and sequence stratigraphy of the Mobarak Formation. ...
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The early carboniferous Mobarak Formation was studied in southern flank of Ayenehvarzan–Dalichai anticline, in Aru and Seyedabad sections, east of Tehran. The aim of this study is to determine microfacies, interpretation of depositional environments and sequence stratigraphy of the Mobarak Formation. In this study, the thickness of Mobarak Formation in Aru and Seyedabad sections varies from 133 to 65 meters and consists of limestone with intercalations of shale and marl. According to lithological characteristics, the Mobarak Formation subdivided into several rock units. The Mobarak Formation is disconformably overlain by Jirud Formation and underlain by Dorod Formation. Ten microfacies have been recognized on the basis of depositional remarks and petrographic analysis. These carbonate facies belong to 4 major sub-environments including beach/tidal flat, lagoon, barrier/sand shoal and open marine. These facies deposited in a homoclinal carbonate ramp and include two sedimentary sequences.
N Kohansal-Ghadimvand; Sh Gholipouri; P Ghazanfari; R Mahari
Abstract
The aim of this study is to determine microfacies and diagenetic processes of the Mobarak Formation with the age of early Carboniferous in Valiabad section, at Karaj-Chalus road. The thickness of the formation at this section is 339 m and consists of limestone with intercalations of shale and marl. ...
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The aim of this study is to determine microfacies and diagenetic processes of the Mobarak Formation with the age of early Carboniferous in Valiabad section, at Karaj-Chalus road. The thickness of the formation at this section is 339 m and consists of limestone with intercalations of shale and marl. According to lithological characteristics, the MobarakFormationis subdivided into 8 rock units and is disconformably overlain by the Lalun Formation and underlain by Dozdeband Formation. Thirteen microfacies have been recognized on the basis of depositional texture and petrographic analysis. These carbonate facies belong to four major sub- environments including beach/tidal flat, lagoon, barrier/sand shoal and open marine. The formation deposited in a homoclinal carbonate ramp.
B Aghababalou; Kh Khosrotehrani; S.M Hoseininezhad
Abstract
The early Carboniferous Mobarak Formation is well exposed in the north of Damghan. It consists of fossiliferous limestone, marly limestone and grey shales. 31 species from 23 genera including: Rossirhynchus adamantinus (Gaetani, 1964), Tomiproductus elegantulus (Tolmmachev, 1924), Pustula cf. altaica ...
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The early Carboniferous Mobarak Formation is well exposed in the north of Damghan. It consists of fossiliferous limestone, marly limestone and grey shales. 31 species from 23 genera including: Rossirhynchus adamantinus (Gaetani, 1964), Tomiproductus elegantulus (Tolmmachev, 1924), Pustula cf. altaica (Tolmachev, 1924), Leptagonia analoga (Phillips, 1841), Hemiplethrorhynchus crassus (Gaetani, 1968), Tylothyris cf. planimedia (Cvancara, 1958), Lamellosathyris aff. Lamellose (Leveille, 1835),Punctospirifer aff. Scabricosta (North, 1920) have been identified from the Labrud section. Four brachiopod assemblage zones show spanning from the Tournaisian to early Visean. The Mobarak Formation at this section overlies the Geirud Formation conformably and underlies the Dorud Formation(?) disconformably.
H. Mosaddegh; A. Barari; H. Hamdi2
Abstract
During the Carboniferous time, Iran was a part of the northern margin of Gondwana. Carboniferous deposits of Iran are characterized by continental to shallow marine deposits. The studied section (Simeh- Kooh) is located in 5 Km Northwest of Damghan city in the east Alborz region. The lower Carboniferous ...
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During the Carboniferous time, Iran was a part of the northern margin of Gondwana. Carboniferous deposits of Iran are characterized by continental to shallow marine deposits. The studied section (Simeh- Kooh) is located in 5 Km Northwest of Damghan city in the east Alborz region. The lower Carboniferous Mobarak Formation consists of variable thickness of limestones interbeded with shale beds. The thickness of this section is about 115 m. The Mobarak Formation overlay the upper Devonian Jeirud Formation with a transitional contact and is unconformably underlain by lower Permian mixed siliciclastic-carbonate succession of Dorud Formation. This research is focused on the conodonts and facies. Conodont elements consist of 13 genus and 19 species. 5 Biozones is identified including, costatus zone (Latest Famennian), Sandbergi-L. crenulata zone, isostaticha-U. crenulata zone (Middle Tournaisian), typicus-anchoralis-latus zone (Late Tournaisian) and G. bilineatus zone (Middle-Late Visean) correspond to global zonation. The Tournaisian succession consist of alternation of organic matter rich shales and dark thin-bedded limestones is supposed to have deposited in a deep marine environment with a low oxygen condition. The paleontological and facies characteristics of Devonian-Carboniferous transition definitely show a rapid sea level rise and flooding event in this time in Eastern Alborz which corresponds with the Hangenberg Bioevent known in other parts of the world.
N. Ranjkesh; Bahaedin Hamdi Hamdi
Abstract
The Mobarak Formation with 347.5 m, thickness is well exposed in Valyabad section , at the Karaj - Chalus road . The lower contact with underlying Laloon Formation is disconformable ,whereas stratigraphic relation to the overlying Dozdeband formation is transitional. According to the lithological ...
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The Mobarak Formation with 347.5 m, thickness is well exposed in Valyabad section , at the Karaj - Chalus road . The lower contact with underlying Laloon Formation is disconformable ,whereas stratigraphic relation to the overlying Dozdeband formation is transitional. According to the lithological character, the studied section can be subdivided into rock units . The lower part of the fm. consist of dark- gray to black limestone as well as marly limestone, while upper part consist mainly of sandy limestone with interbeds of marlstone. According to the microfossil investigation 14 genius and species have been recognized which leads 2 conodont biozones . The both conodont biozones correspond to the international standard conodont biozonation which suggest an Early Tournisian to Middle Visean time interval . in addition , a Namurian age is suggested for deposites of informal Dozdeband formation , based on foraminifers . Received conodont bizones are as :
Neopriniodus peracutus - Polygnathus longiposticus Assemblage- Zone
Hibbardella roundya - Gnathodus girtyi Assemblage- Zone
More over , 5 Holotorian species as well as 6 genuse ,72 species Foraminifers in form of 5 biozone have been distinguished. These biozones are as :
Eotuberitina retligener - Endothyra spirilloformis Assemblage- Zone
Archaediscus permodiscus - Archaediscus(Paraarchaediscus)mixtus Assemblage- Zone
Endostaffella parva - Brunsina pulchera Assemblage- Zone
Tuberitina bulbacea - Kammaena sp. Barren Interval Zone
Lipinella notata - Archaediscus planoarchaediscus Assemblage- Zone
The studied foraminifers support the given age . Conodonts the Color Alteration Index(CAI) correspond 190 to 300 C◦ which indicate dry gas stage or empty of any hydrocarbon.
A. Fallah; B. Hamdi; H. Mosaddegh
Abstract
The studied section (Kiyasar)is situated in Central Alborz,75 Km. southeast of Sari. The thickness of Carboniferous sequences (Mobarak Formation) is 385 meter and consists of thin-bedded limestone at the base and various thickness of limestone (mostly with medium thickness) with intercalations of shales ...
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The studied section (Kiyasar)is situated in Central Alborz,75 Km. southeast of Sari. The thickness of Carboniferous sequences (Mobarak Formation) is 385 meter and consists of thin-bedded limestone at the base and various thickness of limestone (mostly with medium thickness) with intercalations of shales at the top. Because of lithological similarity and the lack of index microfossils in the uppermost of Devonian and lowermost of Carboniferous, deposits, determination of this boundary was impossible in the field and the approximate boundary has been identified after study of lab by conodont elements. Apparently, this boundary is conformable and continual that the rocks at the bottom of its attributed to Khoshyeilagh Formation. This boundary is located in the interval of samples 4.1(late Devonian) and 4.3(lower Carboniferous) which the distance between them is 4m.(thin to medium-bedded limestones).The limit of boundary is distinct with extinction of Genera and Species for example Icriodus costatus, Pelekysgnathus sp. and Polygnathus semicostatus in the late of Devonian(sample4.1)and appearance of species for example Polygnathus spicatus, Spa. crassidentathus, Po. thomasi and Cly. gilwernensis in early Carboniferous (sample4.3). in summery, limestone rocks in alternation with shale of upper Famenian is attributed to lower-middle costatus zone form lower part of Carboniferous rocks in the region. The top of Mobarak Formation is overlaid by alternations of sandstone, shales and limestone (in the middle part), belong of Dorud Formation (lower Permian) with a disconformity. Carboniferous conodonts (20 Genus, 36 Species, 7 Subspecies are reported from Mobarak Fm.,Kiyasar region, for the first time as well as the distinguished following 7 conodont zones: 1) sulcata zone 2) duplicata zone 3) sandbergi-L. crenulata zone 4) typicus zone 5) anchoralis-latus zone 6) texanus- A. scalenus zone 7) Gn. bilineatus zone. According to conodont data Carboniferous sequences in Kiyasar section were deposited from lower Tournaisian to upper Visean time interval.
H. Gholamalian; M. R. Kebriaei zadeh; M. Ghorbani; S.M. Hosseini-Nezhad
Abstract
Investigation on brachiopods and conodonts of Mobarak Formation in Kalariz section confirms the age of Early Tournaisian to Middle Viséan. Some species as Bispathodus aculeatus aculeatus, Bi. stabilis, Spinocarinifera nigra and Shumardella sp.in the lowest part of section show the Early Tournaisisan ...
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Investigation on brachiopods and conodonts of Mobarak Formation in Kalariz section confirms the age of Early Tournaisian to Middle Viséan. Some species as Bispathodus aculeatus aculeatus, Bi. stabilis, Spinocarinifera nigra and Shumardella sp.in the lowest part of section show the Early Tournaisisan age, whereas the middle part is Middle to Late Tournaisian on the basis of the presence of Tomiproductus vaughani, Tomiopsis sp., Scabricosta sp., Polygnathus flabellus, P. rostratus, P. longiposticus, Clydagnathus cavusformis. Some faunas as Marginatia kinghirica and Buxtonia cf. praejuresanensis prove the Early to Middle Viséan for the upper part of section. Three domestic biozones are recognized on the basis of faunal distribution in the stratigraphic column. Biozone 1 (Early Tournaisian): this zone can be recognized by the association of these species: Spinocarinifera nigra, Rossirhynchus adamantinus, Shumardella sp., Cleiothyridina transversa, Bispathodus aculeatus aculeatus, Bi. stabilis, Polygnathus communis communis, P. inornatus. Biozone 2 (Middle to Late Tournaisian): Tomiproductus vaughani, Tomiproductus elegantulus, Tomiopsis sp., Scabricosta sp., Tylothyris planimedia, Syringothyris altaica, Leptagonia analoga, Leptagonia cf. regularis, Ripidomella michelini, Athyris hibernica, Spirifer missouriensis, Schelwienella sp., Leptagonia cf. regularis, Torynifer sp., Polygnathus flabellus, P. longiposticus, P. inornatus, P. aff. inornatus, P. rostratus, P. sp., P. communis communis, Bispathodus stabilis, Pseudopolygnathus primus, Clydagnathus cavusformis. Biozone 3 (Early to Middle Visean): this zone is identified by the presence of some index species as: Buxtonia cf. praejuresanensis, Megachonetes sp., Actinoconchus lamellosus, Orthotetes batesvillensis, Marginatia cf. kinghirica, Balakhoniasp. Mobarak Formation conformably overlies the Geirud Formation and disconformably underlies the Dorud Formation demonstrating Late Viséan to Gzelian hiatus as the result of Hercynian epeirogenesis.
