Stratigraphy and Palaeontology
Hamta Ranjbar; Abbas Ghaderi; Hossein Gholamalian; Vachik Hairapetian
Abstract
Middle Devonian to Lower Carboniferous siliciclastic-carbonate successions in Eastern Alborz are characterized by Khoshyeilagh Formation. It is underlain by the Devonian red siliciclastic sequences and is overlain by the Carboniferous Mobarak Formation, can be divided into three different members; lower ...
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Middle Devonian to Lower Carboniferous siliciclastic-carbonate successions in Eastern Alborz are characterized by Khoshyeilagh Formation. It is underlain by the Devonian red siliciclastic sequences and is overlain by the Carboniferous Mobarak Formation, can be divided into three different members; lower carbonate, middle siliciclastic, and upper carbonate. The Khoshyeilagh Formation comprises various fossil groups of invertebrates, conodonts, palynomorphs and fish remains. In the present study, a collection of microscopic fish remains, obtained from the lower and upper carbonate members in Mighan, north of Shahrood, have been determined and described. This assemblage contains 14 different taxa of chondrichthyan fish including: Cladodoides cf. wildungensis, Ctenacanthiformis gen. et sp. indet, Dalmehodus turnerae, Deihim mansureae, Lissodus lusavorichi, Phoebodus aff. turnerae, Phoebodus fastigatus, Phoebodus gothicus gothicus, Phoebodus gothicus transistans, Roongodus phijani, Siberiodus mirabilis, Squatinactis glabrum, Stethacanthus resistens and Thrinacodus ferox. Some specimens of scales and teeth of actinopterygian and osteichthyan fishes are also present which all indicate a shallow environment of the continental shelf. The associated conodonts with this assemblage demonstrate the age of Frasnian (rhenana biozone) to early Tournaisian (duplicata biozone) for the whole succession.
Stratigraphy and Palaeontology
Hossein Gholamalian; Roya Fanati Rashidi
Abstract
Kazhdumi Formation strata in Anguran section (NW Bandar Abbas) are investigated and eight echinoid species belonging to eight genera have been identified. These species are: Tetragramma malbosii, Orthopsis ruppelli, Phyllobrissus aff. angustatus, Epiaster dartoni, Hemiaster sp., Pliotoxaster comanchei, ...
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Kazhdumi Formation strata in Anguran section (NW Bandar Abbas) are investigated and eight echinoid species belonging to eight genera have been identified. These species are: Tetragramma malbosii, Orthopsis ruppelli, Phyllobrissus aff. angustatus, Epiaster dartoni, Hemiaster sp., Pliotoxaster comanchei, Iraniaster douvillei, Coenholectypus planatus. Iraniaster douvillei that has already been reported from the Coniacian – Santonian beds of Lorestan Zone (West of Iran); is present in the Albian – Cenomanian strata of Anguran section. So; we can propose the new range of Middle Albian – Santonian for this species. Kazdumi Formation in the studied area has the age of Middle Albian to Early Cenomenian on the basis of foraminifers those accompany with echinoids. This formation conformably overlies the Dariyan Formation and disconfomably underlies the Gurpi Formation.
T Ahmadi; V Hairapetian; H Gholamalian; M.R Vaziri; M Dastanpour
Abstract
From Late Devonian-Early Carboniferous strata in the Kerman area fourteen chondrichthyan taxa were identified. The abundance of chondrichthyan teeth in Famennian strata is considerable. The high abundance of protacrodonts and larger proportion of shallower shelves of pheobodonts appeared to dominate ...
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From Late Devonian-Early Carboniferous strata in the Kerman area fourteen chondrichthyan taxa were identified. The abundance of chondrichthyan teeth in Famennian strata is considerable. The high abundance of protacrodonts and larger proportion of shallower shelves of pheobodonts appeared to dominate in a shallow environment at the Famennian. The chondricthyan assemblage from the Famennian of the Hutk section resembles the Chahriseh fauna in Esfahan district that reveals similar palaeoenvironmental conditions in Central Iran basin. The occurrence of Deihim mansureae in duplicate Zone marks the youngest record for the species up to Early Tournaisian.
H Gholamalian; R Fanati-Rashidi; S.H Sajadi
Abstract
Mishan Formation in the Gohreh section (north of Bandar Abbas) is investigated in order to identify echinoid species. Systematic study of echinoids shows presence of two orders in the studied area; Spatangoida and Clypeasteroida. Five described species are: Clypeaster sp., Clypeaster goirensis, Schizaster ...
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Mishan Formation in the Gohreh section (north of Bandar Abbas) is investigated in order to identify echinoid species. Systematic study of echinoids shows presence of two orders in the studied area; Spatangoida and Clypeasteroida. Five described species are: Clypeaster sp., Clypeaster goirensis, Schizaster granti, Moira adamthi, Maretia ranjitpurensis.The co-occurrence of index associated foraminifers such asOrbulina universaand Globigerinoides trilobus shows the Middle Miocene age for the echinoid bearing beds.
H Gholamalian; S Ghoreishi Maremy; M Parvaneh Nezhad Shirazi
Abstract
The Bahram Formation equivalent sequence in the Gerik section (eastern Zarand) displays middle Frasnian to early Famennian age on the basis of conodont investigation. Twenty-eight species and subspecies were identified. Seven biozones were recognized on the basis of vertical distribution of these taxa ...
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The Bahram Formation equivalent sequence in the Gerik section (eastern Zarand) displays middle Frasnian to early Famennian age on the basis of conodont investigation. Twenty-eight species and subspecies were identified. Seven biozones were recognized on the basis of vertical distribution of these taxa along the stratigraphic column; older than Upper hassi Zone, Upper hassi – jamieae zones, ?Lower rhenana Zone, Upper rhenana – linguiformis zones, Lower triangularis, Middle triangularis - Lower crepida zones, Middle – Upper crepida zones. Index conodont species those are recovered from the biostrome horizon in the lower part of section proved the middle Frasnian age (Upper hassi – jamieae zones). From view of conodont fauna, lithostatigraphy and age; the Gerik section is comparable with other successions of the Bahram Formation in Kerman, Tabas and Esfahan areas and shows a shallow sedimentary environment.
H. Gholamalian; S. M. Hosseini-Nezhad; Z. Khosravi; I. Turkzadeh Mahani
Abstract
Bahram Formation equivalent sequence in the Baghin area spans late Givetian to late Frasnian age. Thirty-two species and subspecies are identified. Ancyrodella alata, An. pristina, Polygnathus aspelundi, P. aequalis, P. subincompletus,P. politus, Icriodus alternatus alternatus, I. iowaensis iowaensis ...
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Bahram Formation equivalent sequence in the Baghin area spans late Givetian to late Frasnian age. Thirty-two species and subspecies are identified. Ancyrodella alata, An. pristina, Polygnathus aspelundi, P. aequalis, P. subincompletus,P. politus, Icriodus alternatus alternatus, I. iowaensis iowaensis are of important species. The presence of An. pristina and An. alata in the lower part of Bahram Formation in this section shows the late Givetian marine transgression. Five conodont biozones are recognized on the basis of stratigraphic ranges of species: Lower to Upper falsiovalis zones; transitans to punctata zones; Lower hassi to jamieae zones; Lower rhenana Zone; and Upper rhenana to ?linguiformis zones.
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.
S. M. Hosseini-Nezhad; M. Yazdi; M. Ghobadi-Pour; H. Gholamalian
Abstract
Geirud formation deposits of Kalariz in the Eastern Alborz start with a relatively thick sequence of sandstone, shale, and red, white and brown colored siltstone changing into yellow dolomitic layers, fossiliferous limestone and shaly or marly limestone. This formation ...
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Geirud formation deposits of Kalariz in the Eastern Alborz start with a relatively thick sequence of sandstone, shale, and red, white and brown colored siltstone changing into yellow dolomitic layers, fossiliferous limestone and shaly or marly limestone. This formation lies over Mila formation with a disconformity and covered transitionally by limestones of Mobarak formation. In the above mentioned sequence, numerous and various conodonts and brachiopods were identified. Based on the distribution of brachiopoda, two assemblage zones and based on the conodonts, four assemblage zones were recognized with Famennian and Strunian age. The first brachiopoda biozone, equivalent to the first and second conodont biozones, belongs to early Famennian age (older than late crepida zone and romboidea to late trachytera zone) and the second Brachiopoda biozone which is equivalent to conodont biozone of number three and four has the late Famennian age (postera to late expansa zone and praesulcata zone). Paleontological and stratigraphical evidence indicates that Frasnian sediments are absent in the study area.
