Английская Википедия:Gnishik Formation

Материал из Онлайн справочника
Перейти к навигацииПерейти к поиску

Шаблон:Short description Шаблон:Infobox rockunit

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

The thin-bedded limestones of the formation reach a thickness of Шаблон:Convert in the Julfa section of northwestern Iran and Шаблон:Convert 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 Wentzellophyllum gnishikense was named after the formation.

Description

The Gnishik Formation was first formally described by Arakelyan in 1964, based on a section in the Gnishik River 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 Шаблон:Convert in the Julfa section of northwestern Iran. In Iran, the formation overlies the Dorud Formation and is overlain by the Khachik Formation,[3] while in Armenia the formation rests on top of the Asni Formation and is overlain by the Arpa Formation.[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 Murgabian,[5] which belongs to the Wordian stage of the Middle Permian.[1] The Gnishik Formation is correlated with the Ruteh and Nesen Formations,[6] and the Kuffengian stage of Chinese chronostratigraphy.[7]

Fossil content

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

Invertebrates

Trilobites
Cephalopods
Gastropods
Corals
Crinoids
Rhynchonellata
Strophomenata
Stenolaemata
Fusulinina
Foraminifera

Flora

Dasycladophyceae
Rhodophyceae

See also

Шаблон:Div col

Шаблон:Div col end

References

Шаблон:Reflist

Bibliography

Geology
Paleontology

  1. 1,0 1,1 1,2 Gnishik Formation in the Paleobiology Database
  2. Leven, 1998, p.302
  3. 3,0 3,1 Saidi et al., 1997, p.198
  4. Leven, 1998, p.301
  5. Leven, 1998, p.308
  6. Leven, 1998, p.314
  7. Leven, 1998, p.320
  8. 8,00 8,01 8,02 8,03 8,04 8,05 8,06 8,07 8,08 8,09 8,10 8,11 8,12 8,13 8,14 8,15 8,16 8,17 8,18 8,19 8,20 8,21 8,22 8,23 8,24 8,25 8,26 8,27 8,28 8,29 8,30 8,31 8,32 8,33 8,34 8,35 8,36 8,37 8,38 8,39 8,40 8,41 8,42 8,43 8,44 8,45 8,46 8,47 8,48 Ruzhentsev & Sarycheva
  9. 9,0 9,1 9,2 9,3 9,4 9,5 9,6 9,7 9,8 9,9 Stepanov et al., 1969
  10. 10,0 10,1 10,2 10,3 Kropatcheva, 1999
  11. 11,0 11,1 11,2 11,3 11,4 11,5 11,6 11,7 11,8 11,9 Kotlyar et al., 1989
  12. 12,00 12,01 12,02 12,03 12,04 12,05 12,06 12,07 12,08 12,09 12,10 Morozova, 1970
  13. 13,0 13,1 13,2 13,3 Ezaki, 1991
  14. Stukalina, 1999
  15. 15,0 15,1 15,2 15,3 15,4 15,5 Nakamura & Golshani, 1981
  16. 16,0 16,1 16,2 Shishova, 1964
  17. Gennari & Rettori, 2019