Gnishik Formation

Gnishik Formation
Stratigraphic range: Wordian (late )
~268–265 Ma

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Gnishik Formation; Stratigraphic range: Wordian (late ); ~268–265 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Formation
Underlies	(Armenia); Khachik Formations (Iran)
Overlies	(Armenia); (Iran)
Thickness	300 m (980 ft) (Armenia); 670 m (2,200 ft) (Iran)
Lithology
Primary	Limestone
Other	Shale
Location
Coordinates	39°00′N 45°00′E / 39.0°N 45.0°ECoordinates: 39°00′N 45°00′E / 39.0°N 45.0°E
Approximate paleocoordinates	9°06′S 41°24′E / 9.1°S 41.4°E
Region	Transcaucasia
Country	Armenia; Azerbaijan; Iran
Extent	Alborz Mountains
Type section
Named for
Named by	Arakelyan
Year defined	1964
	Gnishik Formation (Caucasus mountains)

The Gnishik Formation is a geologic formation in Armenia, Azerbaijan and Iran. It preserves fossils dating back to the Wordian stage of the Permian period.^[1]

The thin-bedded limestones of the formation reach a thickness of 670 metres (2,200 ft) in the Julfa section of northwestern Iran and 300 metres (980 ft) in the Arpa River valley of Armenia. The sediments were deposited in an open marine setting at the northern edge of the Paleo-Tethys Ocean.

The coral was named after the formation.

Description[]

The Gnishik Formation was first formally described by Arakelyan in 1964, based on a section in the valley, after which the formation was named. The formation is mostly represented by thin-bedded, occasionally shaly, dark grey and black bituminous foraminiferal-algal biodetrital limestones. The occasional admixture of clayey and terrigenous material colors the limestones light grey and yellowish. The thin-bedded layers alternate with coarser-bedded compact varieties.^[2]

The open marine limestones of the formation reach a thickness of 670 metres (2,200 ft) in the Julfa section of northwestern Iran. In Iran, the formation overlies the and is overlain by the Khachik Formation,^[3] while in Armenia the formation rests on top of the and is overlain by the .^[4] The Gnishik Formation represents an increase in subsidence rate in the Permian.^[3] The sediments were deposited at the northern edge of the Paleo-Tethys Ocean.

The formation is dated to the late ,^[5] which belongs to the Wordian stage of the Middle Permian.^[1] The Gnishik Formation is correlated with the and ,^[6] and the stage of Chinese chronostratigraphy.^[7]

Fossil content[]

Among many others, the following fossils have been reported from the formation:^[1]

Invertebrates[]

Trilobites

^[8]
^[8]^[9]
^[8]

Cephalopods

Orthocerida indet.^[9]

Gastropods

Corals

^[10]
^[11]
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^[11]^[12]
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^[13]
^[10]^[11]
^[12]
^[8]
^[11]
^[12]
^[13]
^[12]
^[13]
Sinopora asiatica^{[disambiguation needed]}^[13]
^[12]
^[8]
^[12]
^[8]
^[10]
^[10]
^[12]
^[12]
^[11]
^[11]

Crinoids

^[14]

Rhynchonellata

^[15]
^[15]
^[8]
^[15]
^[15]

Strophomenata

^[15]
^[8]
^[8]
^[15]

Stenolaemata

^[8]^[16]^[12]
^[16]
Septopora lineata^[16]

Fusulinina

^[8]
^[8]
^[8]
^[8]
^[8]
^[8]
^[8]
^[8]
^[8]
^[8]
^[8]
^[8]
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^[8]
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Foraminifera

^[17]

Flora[]

Dasycladophyceae

Rhodophyceae

References[]

^ ^a ^b ^c Gnishik Formation in the Paleobiology Database
^ Leven, 1998, p.302
^ ^a ^b Saidi et al., 1997, p.198
^ Leven, 1998, p.301
^ Leven, 1998, p.308
^ Leven, 1998, p.314
^ Leven, 1998, p.320
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q ^r ^s ^t ^u ^v ^w ^x ^y ^z ^aa ^ab ^ac ^ad ^ae ^af ^ag ^ah ^ai ^aj ^ak ^al ^am ^an ^ao ^ap ^aq ^ar ^as ^at ^au ^av ^aw Ruzhentsev & Sarycheva
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Stepanov et al., 1969
^ ^a ^b ^c ^d Kropatcheva, 1999
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Kotlyar et al., 1989
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k Morozova, 1970
^ ^a ^b ^c ^d Ezaki, 1991
^ Stukalina, 1999
^ ^a ^b ^c ^d ^e ^f Nakamura & Golshani, 1981
^ ^a ^b ^c Shishova, 1964
^ Gennari & Rettori, 2019

Bibliography[]

Geology

Leven, Ernst J.A. 1998. Permian fusulinid assemblages and stratigraphy of the Transcaucasia. 104. 299–328. Accessed 2020-08-01.
Saidi, Abdollah; Marie-Françoise Brunet, and Luc-Emmanuel Ricou. 1997. Continental accretion of the Iran Block to Eurasia as seen from Late Paleozoic to Early Cretaceous subsidence curves. 10. 189–208. doi:10.1080/09853111.199

Paleontology

Gennari, Valerio, and Roberto Rettori. 2019. Globigaetania angulata gen. n. sp. n. (Globivalvulininae, Foraminifera) from the Wordian (Middle Permian) of NW Iran. 125. 1–11. doi:10.13130/2039-4942/11054
Kropatcheva, G. S. 1999. Novie vidi pozdnepermski rugoz zakavkaziya - New materials of Late Permian rugosans from the Caucasus. 11. 24–32.
Stukalina, G. A. 1999. The Late Permian crinoids from Primorye, Transcaucasia, and North Caucasus. Paleontological Journal 33. 139–146.
Ezaki, Y. 1991. Permian corals from Abadeh and Julfa, Iran, West Tethys. 23. 53–146.
Kotlyar, G. V.; Y.u. D. Zakharov; G. S. Kropatcheva; G. P. Pronina; I. O. Chedija, and V. I. Burago. 1989. Evolution of the latest Permian biota: Midian regional stage in the USSR, 1–184. ..
Nakamura, K., and F. Golshani. 1981. Notes on the Permian brachiopod genus Cryptospirifer. , Series 4, Geology and Mineralogy 20. 67–77.
Morozova, I. P. 1970. Mshanki Pozdnei Permi. Akademiya Nauk SSSR, Trudy Paleontologicheskogo Instituta 122. 1–346.
Stepanov, D. L.; F. Golshani, and J. Stöcklin. 1969. Upper Permian and Permian-Triassic boundary in north Iran. 12. 1–72.
Ruzhentsev, V. E., and T. G. Sarycheva. 1965. The Development and Change of Marine Organisms at the Palaeozoic-Mesozoic Boundary. Akademiya Nauk SSSR, Trudy Paleontologicheskogo Instituta 108. 1–431.
Shishova, N. A. 1964. Novyye Pozdnepermskiye Rabdomezonidy Sovetskogo Soyuza. Paleontologicheskii Zhurnal 1964. 52–57.

[PBDB-1] Gnishik Formation in the Paleobiology Database

[Leven1998-p302-2] Leven, 1998, p.302

[Saidi1997-p198-3] Saidi et al., 1997, p.198

[Leven1998-p301-4] Leven, 1998, p.301

[Leven1998-p308-5] Leven, 1998, p.308

[Leven1998-p314-6] Leven, 1998, p.314

[Leven1998-p320-7] Leven, 1998, p.320

[Ruzhentsev1965-8] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q ^r ^s ^t ^u ^v ^w ^x ^y ^z ^aa ^ab ^ac ^ad ^ae ^af ^ag ^ah ^ai ^aj ^ak ^al ^am ^an ^ao ^ap ^aq ^ar ^as ^at ^au ^av ^aw Ruzhentsev & Sarycheva

[Stepanov1969-9] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Stepanov et al., 1969

[Kropatcheva1999-10] Kropatcheva, 1999

[Kotlyar1989-11] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Kotlyar et al., 1989

[Morozova1970-12] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k Morozova, 1970

[Ezaki1991-13] Ezaki, 1991

[Stukalina1999-14] Stukalina, 1999

[Nakamura1981-15] ^ ^a ^b ^c ^d ^e ^f Nakamura & Golshani, 1981

[Shishova1964-16] Shishova, 1964

[Gennari2019-17] Gennari & Rettori, 2019

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