Stratigraphy and Palaeontology
Parisa Mohammadi; Abbas Ghaderi; Ali Reza Ashouri
Abstract
The Julfa region in East Azerbaijan Province exhibits one of the best continuous marine sedimentary successions across the Permian to Triassic boundary. The present study is focused on the brachiopod contents of the Julfa beds in Qareh-Goz section (41.5 m thickness) in the south of Julfa. This study ...
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The Julfa region in East Azerbaijan Province exhibits one of the best continuous marine sedimentary successions across the Permian to Triassic boundary. The present study is focused on the brachiopod contents of the Julfa beds in Qareh-Goz section (41.5 m thickness) in the south of Julfa. This study is led to the determination of 11 genera and 21 species of the orders Athyridida, Orthotetida, Orthida, Productida, Spiriferida, and Terebratulida, all representing the Cathaysian bioprovince for this area in the Western Paleotethys. Accordingly, four Wuchiapingian biozones, including Araxilevis intermedius Zone, Araxilevis intermedius-Permophricodothyris ovata Interval zone, Permophricodothyris ovata Zone, and Transcaucasathyris araxensis Zone, have been detected. These biozones correlate well through the other stratigraphic sections of the Julfa area in the Ali Bashi and Zal Mountains, Dorasham section in the Transcaucasia, Hembast Formation in the Abadeh area, and Nesen Formation in the central Alborz, approving the potential of these brachiopods in biocorrelation at a regional scale in the Late Permian.
Economic Geology
Morteza Delavari; Amir Ali Tabakh Shabani; Samaneh Ghanbari
Abstract
The Oligocene dacitic volcanic rocks display widespread exposures in south of Julfa (eastern Azerbaijan). They generally show porphyritic to hyalo-porphyritic textures with major minerals of plagioclase, amphibole, quartz and biotite. Electron probe micro analyzer (EPMA) data indicates oscillatory zoning ...
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The Oligocene dacitic volcanic rocks display widespread exposures in south of Julfa (eastern Azerbaijan). They generally show porphyritic to hyalo-porphyritic textures with major minerals of plagioclase, amphibole, quartz and biotite. Electron probe micro analyzer (EPMA) data indicates oscillatory zoning and chemical variation of amphiboles (pargasite and edenite). The plagioclase crystals are, chemically, andesine (An= 29-51%) which mostly display oscillatory zoning. Based on geobarometric calculations, plagioclase displays pressures of 5 to 8 kb and amphiboles demonstrate different pressure ranges of 1.5 to 3 and 5 to 9 kb. Moreover, geothermometric calculations of plagioclase and amphibole provide temperatures of 1020-1050 and 850-900 °C, respectively. On the basis of geobarometric results, crystallization and growth of the minerals took place in magmatic chambers of different levels. Some of the amphiboles nucleated in lower continental crust and subsequently grown during magma ascent in middle crust whereas some others crystallized in the upper continental crust. Therefore, existence of minerals of different levels inside the studied rocks could be related to magma mixing in shallow magma chambers.
Stratigraphy and Palaeontology
Abbas Ghaderi; Mahdi Badpa; Ali Reza Ashouri
Abstract
To study of Permian corals at the northwest of Iran, Ali-Bashi stratigraphic section was selected and sampled. After microscopic studies of several longitudinal, transverse, and serial sections were obtained from more than 180 coral fossils, 12 species belonging to 6 genera of rogues and tabula corals ...
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To study of Permian corals at the northwest of Iran, Ali-Bashi stratigraphic section was selected and sampled. After microscopic studies of several longitudinal, transverse, and serial sections were obtained from more than 180 coral fossils, 12 species belonging to 6 genera of rogues and tabula corals were determined. The Permian succession of the Julfa area is the dominion of two types of coral fauna. Waagenophyllidae fauna that is the territory of the colonial coral forms comprises typically Tethyan indicators such as Ipciphyllum and Waagenophyllum with the age of Middle?- Late Permian. Cyathaxonia fauna, Late Permian in age, include terminal phylogenetic representatives of the rugose corals, mostly composed of solitary one Pentaphyllum. This genus is persistent till the vicinity of the extinction horizon at the near end Permian in the Ali Bashi Formation topmost horizon. Also, the last standing tabula coral before the Late Permian extinction in the Julfa region is the genus Protomichelinia. The Permian coral fauna of the NW Iran finely corresponds to those of the Abadeh region in Central Iran and Transcaucasus. The Waagenophyllidae forms are the same as South China fauna, whereas the Cyathaxonia ones reveal a high endemism in the Late Permian of NW Iran.
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.
M Sadeghi; K Rashidi; R Shabanian
Abstract
Succession of Permian system in Pir-Eshagh stratigraphic section has been mesured totally about 1400 m, which it's base consists mainly of Dorud formation with thickness of about 100 m which in turn has been overlain by Ruteh and Nesen formations with thickness of 1100 and 200 m respectively. Lower boundary ...
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Succession of Permian system in Pir-Eshagh stratigraphic section has been mesured totally about 1400 m, which it's base consists mainly of Dorud formation with thickness of about 100 m which in turn has been overlain by Ruteh and Nesen formations with thickness of 1100 and 200 m respectively. Lower boundary of this succession overlay unconformablyon the Devonian volcanic rocks and the upper parts continuously and concordantly is changed to yellow lamellar limestone, Elika formation that deposited in lower and middle Triassic. For identification of various calcareous genus and species of algae in these sediments,we systematically selected 220 thin sections from the lower bound up to the upper bound based on the lithological changes perpendicular to the strike of layers. In this study, we identified 7 genus and 9 types of dasycladaceae green algae Mizzia sp., Mizzia velebitana, Mizzia cornuta,Macroporella cf. nuda, Macroporella sp., Epimastopora sp., Epimastopora symetrica, Paraepimastopora longutuba, Epimastopora likana, Epimastoporella japonica, Tabasoporella tulipaformis, Gyroporella sp., Gyroporella nipponica, and 2 genus and 5 types of gymnocodiacea algae family Permocalculus sp., Permocalculus cf. dikenliderensis, Permocalculus fragilis, Permocalculus plumosus, Permocalculus tenellus, Gymnocodium sp., Gymnocodiumbellerophontis at Ruteh and Nesen formations. Also, Tabasoporella tulipaformis algae belonging to the dasycladaceae family which has been introduced from the Jamal formation, for the first time was identified and reported from the carbonated units in the northwest of Iran.
