A. Yavari; M. Ghavidel syooki; M. R. Majidifard; S. H. Vaziri
Abstract
The Kazhdumi Formation is well exposed and accessible in Tang-e Maghar, northwest of Behbahan city, Zagros basin. In this area, this formation has a thicknees of 344 m and it mainly consists of alternation of black - gray shale with medium – thin-bedded cream – gray argillaceous limestone. ...
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The Kazhdumi Formation is well exposed and accessible in Tang-e Maghar, northwest of Behbahan city, Zagros basin. In this area, this formation has a thicknees of 344 m and it mainly consists of alternation of black - gray shale with medium – thin-bedded cream – gray argillaceous limestone. The lower contact of the Kazhdumi Formation is disconformable with Daryan Formation and conformable with the Sarvack Formation at the top. A total of 220 ammonite bearing surface samples were collected including the uppermost part of the Daryan Formation (5m) and the whole thickness of the Kazhdumi Formation (344m). This investigation resulted in 21 species (15 genera) which belong to six families. The encountered ammonite species of the upper part of the Daryan Formation and the whole Kazhdumi Formation consist of Douvilleiceras sp., Douvilleiceras cf. mammillatum, Epicheloniceras subnodosocostum– buxtorfi, Hypacanithoplites cf. elegnas, Acanthohoplites cf. aschiltaensis, Nolaniceras nolani, Parahoplites cf. melchioris, Venezoliceras sp., Venezoliceras cf. venezolanum, Mirapelia cf. buarquianum, Mirapelia sp., Oxytropidoceras carbonarium, Oxytropidoceras cf. roissyanum, Hysteroceras cf. orbignyi, Hysteroceras sp., Tonohamites cf. aequicingulatus, Mortoniceras sp., Mortoniceras aff. inflatum, Dufrenoyia sp., Hemiptychoceras cf. gaultinum and Scaphites sp.Amongst these ammonite species, Scaphites sp. and Hemiptychoceras gaultinum are recorded for the first time and the remainder has previously been recorded from this rock unit in the Zagros basin. Likewise, based on stratigraphic potential of the encountered ammonite species the lower Aptian is suggested for the upper part of the Daryan Formation and upper Aptian –upper Albian for the Kazhdumi Formation.Therefore, a hiatus is present between the Daryan and Kazhdumi formations, encompassing the middle Aptian.
S Abbasi; B Hamdi; M.R Majidifard
Abstract
Sampling and study of Devonian deposits in North West Iran has done in two separate sections. 1) Illangareh section, 20 km far from NE the Maku city 2) peyr-es-hag composite section, situated South Jufa (W of Peyr-es-hag and Chay kasan villages). Because less work has been undertaken in the cited sections, ...
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Sampling and study of Devonian deposits in North West Iran has done in two separate sections. 1) Illangareh section, 20 km far from NE the Maku city 2) peyr-es-hag composite section, situated South Jufa (W of Peyr-es-hag and Chay kasan villages). Because less work has been undertaken in the cited sections, in this research, microremains (fish teeth, scales and bone fragments) of Cartilaginous fish (Chondrichtyes), Osteichtyes (Acanthodians), fauna are known from the Devonian deposits. Index microvertebrates obtained from the cited above sections are: Siberiodus mirabilis, Phoebodus gothicus, Phoebodus turnerae, , Body scale Holonema sp., Sarcopterygian scale, Ischnacanthid jaw, Cheiracanthus sp., Ertychius intermedius Cladodus wildungensis. According to biostratigraphy and paleogeography these microremains can be comparing with other parts of Iran, neighbors, other parts of world. This assemblage show spread of shallow shelf environment of the northern margin of Gondwana during Middle-Late Devonian time.
Sedimentology
A. Rahimi; M. H. Adabi; A. Nabati; M. R. Majidifard; A. M. Jamali
Abstract
Carbonate sequences of the Shotori Formations (Middle Triassic) with a thickness of 308 m, were deposited in the Kalmard region of the Tabas city in Central Iran basin. The lower contact of the formation gradually and conformably overlies the Sorkhshale Formation and upper contact is faulted. The Shotori ...
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Carbonate sequences of the Shotori Formations (Middle Triassic) with a thickness of 308 m, were deposited in the Kalmard region of the Tabas city in Central Iran basin. The lower contact of the formation gradually and conformably overlies the Sorkhshale Formation and upper contact is faulted. The Shotori Formation is mainly composed of thick to medium bedded fine-coarsely crystalline dolomites with a thickness of 250 m with interbeds of thin bedded limestone and sandstone. The Shotori Formation is mainly composed of fine-coarsely crystalline dolomite. Based on petrographic (size and fabric), and elemental studies (Ca, Mg, Na, Sr, Fe, Mn), five dolomite types were recognized. Variation in dolomite types is mainly related to early to late diagenetic processes, changing the composition of dolomitizing fluids. Geochemical studies also indicate that medium to coarse grain dolomites formed in meteoric diagenesis under reducing conditions. Mechanism of dolomitization for dolomite type 1 is sabkha model, for dolomite types 2 and 3 is mixing zone and is burial model for dolomite types 4 and 5.
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.
S Abbasi; B Hamdi; M.R Majidifard
Abstract
Study of conodont fauna from the Illanghareh Formation in Illanghareh, Illanlu and Pir-Eshag sections provide new data on the stratigraphy of this formation in the North West Iran. Illanghareh section is a terrigenous-carbonate rock sequence, consists mainly of quartzarenite sandstone, shale, and carbonate ...
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Study of conodont fauna from the Illanghareh Formation in Illanghareh, Illanlu and Pir-Eshag sections provide new data on the stratigraphy of this formation in the North West Iran. Illanghareh section is a terrigenous-carbonate rock sequence, consists mainly of quartzarenite sandstone, shale, and carbonate rocks. This sequence generally represents shallow-water Polygnathid-Icriodid biofacies and yielded five biozones: varcus, Older than rhenana, rhenana – linguiformis, Middle triangularis – Late trachytera, postera – expansa. Tectonic activities and erosion caused the Middle Devonian strata in the base of Illanghareh section to be omitted and the varcus Biozone is not recorded. Upper Devonian (Upper Famennian) rock units change into Carboniferous strata with a sedimentary gap though it is not recognizable in the field and no evidence of erosional surface is recognized. It is however, shown between Late Famennian and Late Turnaisian via conodonts recorded. The biozone bilineatus- bolandensis was also recorded in lower part of Carboniferous strata studied here.
B Ghasemshirazi; M.R Majidifard; A Kheradmand; T Mohtat
Abstract
In this research, the Campanian -Maastrichtian deposits in Jupar section, Central Iran have been studied to determine biozonation and Paleobathymetry of the deposits. The planktonic and benthic foraminifera were studied in order to assign palaeobathymetry of the Campanian- Maastrichtian deposits. A depth ...
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In this research, the Campanian -Maastrichtian deposits in Jupar section, Central Iran have been studied to determine biozonation and Paleobathymetry of the deposits. The planktonic and benthic foraminifera were studied in order to assign palaeobathymetry of the Campanian- Maastrichtian deposits. A depth of 490- 650 m was assigned for most parts of the sediments according to planktonic/epibenthic ratio and the regression equation D = e (3.58718+ (0.03534 × %P*)). In the present investigation, 58 planktonic species of 27 genera have been identified. The Campanian -Maastrichtian deposits is divided into 7 biozones on the basis of planktonic foraminifera, which are cosmopolitan and consist of biozone1-Globotruncanita elevata Partial Range Zone, Biozone2- Globotruncana ventricosa Interval Zone, Biozone3- Globotruncanita calcarata Interval Zone, Biozone4- Globotruncanella havanensis Partial range zone , Biozone5- Globotruncana aegyptiaca Interval zone, Biozone6- Gansserina gansseri Interval zone, and Biozone7- Contusotruncana contusa Interval Zone.
K. Seyed Emami; N. Behfar; M. R. Majidifard; A. Behfar
Abstract
Middle Jurassic strata are well developed northeast of Damghan (E Alborz). At the study section the Dalichai Formation has a maximum thickness of 156 m, consisting of an alternation of bluish-grey limestones and marls, being subdivided into 4 members. The lower boundary with the siliciclastics of the ...
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Middle Jurassic strata are well developed northeast of Damghan (E Alborz). At the study section the Dalichai Formation has a maximum thickness of 156 m, consisting of an alternation of bluish-grey limestones and marls, being subdivided into 4 members. The lower boundary with the siliciclastics of the underlying Shemshak Formation is unconformity, due to the Mid-Cimmerian tectonic event, whereas the upper boundary with the light and cliff-forming carbonates of the Lar Formation is gradational. The Dalichai Formation at the study section is very fossiliferous. Summing up 1750 fossil specimens were collected, among which the ammonoids with 1491 specimens clearly predominate. Altogether 27 genera, 33 species of ammonites, belonging to 6 biozones (Parkinsoni Zone, Zigzag-Aurigerus zones, Subcontractus Zone, Bullatus-Gracilis zones, Anceps-Coronatum zones, Athleta Zone) has been recognized. In addition 17 genera and 8 species of planktonic and benthic foraminifers are described.These can be divided into 2 biozones. The fossil-content is mainly concentrated within few meters of red and nodular limestone in the upper part of the section. Based on the ammonite fauna the age of the Dalichai Formation in the investigated area ranges from Upper Bajocian to Oxfordian. Paleobigeographically the fauna shows close relationship to western Europe and Sub-Mediterranean region. This indicates a paleogeographic position of the area at the northern Tethys during the Middle-Upper Jurassic.
