Gnishik Formation

Last updated
Gnishik Formation
Stratigraphic range: Wordian (late Murgabian)
~268–265  Ma
O
S
D
C
P
T
J
K
Pg
N
Type Formation
Underlies Arpa Formation (Armenia)
Khachik Formations (Iran)
Overlies Asni Formation (Armenia)
Dorud Formation (Iran)
Thickness300 m (980 ft) (Armenia)
670 m (2,200 ft) (Iran)
Lithology
Primary Limestone
Other Shale
Location
Coordinates 39°00′N45°00′E / 39.0°N 45.0°E / 39.0; 45.0
Approximate paleocoordinates 9°06′S41°24′E / 9.1°S 41.4°E / -9.1; 41.4
Region Transcaucasia
CountryArmenia
Azerbaijan
Iran
Extent Alborz Mountains
Type section
Named for Gnishik River
Named byArakelyan
Year defined1964
Caucasus topo map-blank.svg
Red pog.svg
Red pog.svg
Red pog.svg
Red pog.svg
Red pog.svg
Red pog.svg
Red pog.svg
Red pog.svg
Red pog.svg
Red pog.svg
Red pog.svg
Red pog.svg
Gnishik Formation (Caucasus mountains)

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]

Contents

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 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 670 metres (2,200 ft) 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

Related Research Articles

<span class="mw-page-title-main">Permian</span> Sixth and last period of the Paleozoic Era 299–252 million years ago

The Permian is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period 298.9 million years ago (Mya), to the beginning of the Triassic Period 251.902 Mya. It is the last period of the Paleozoic Era; the following Triassic Period belongs to the Mesozoic Era. The concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the region of Perm in Russia.

In the geologic timescale, the Capitanian is an age or stage of the Permian. It is also the uppermost or latest of three subdivisions of the Guadalupian Epoch or Series. The Capitanian lasted between 264.28 and 259.51 million years ago. It was preceded by the Wordian and followed by the Wuchiapingian.

<span class="mw-page-title-main">Carnian</span> First age of the Late Triassic epoch

The Carnian is the lowermost stage of the Upper Triassic Series. It lasted from 237 to 227 million years ago (Ma). The Carnian is preceded by the Ladinian and is followed by the Norian. Its boundaries are not characterized by major extinctions or biotic turnovers, but a climatic event occurred during the Carnian and seems to be associated with important extinctions or biotic radiations. Another extinction occurred at the Carnian-Norian boundary, ending the Carnian age.

In the geologic timescale, the Wordian is an age or stage of the Permian. It is the middle of three subdivisions of the Guadalupian Epoch or Series. The Wordian lasted between 266.9 and 264.28 million years ago (Ma). It was preceded by the Roadian and followed by the Capitanian.

<span class="mw-page-title-main">Changhsingian</span> Ninth and last stage of the Permain

In the geologic time scale, the Changhsingian or Changxingian is the latest age or uppermost stage of the Permian. It is also the upper or latest of two subdivisions of the Lopingian Epoch or Series. The Changhsingian lasted from 254.14 to 251.9 Ma ago. It is preceded by the Wuchiapingian age/stage and is followed by the Induan age/stage.

<span class="mw-page-title-main">Cimmeria (continent)</span> Ancient string of microcontinents that rifted from Gondwana

Cimmeria was an ancient continent, or, rather, a string of microcontinents or terranes, that rifted from Gondwana in the Southern Hemisphere and was accreted to Eurasia in the Northern Hemisphere. It consisted of parts of present-day Turkey, Iran, Afghanistan, Pakistan, Tibet, China, Myanmar, Thailand, and Malaysia. Cimmeria rifted from the Gondwanan shores of the Paleo-Tethys Ocean during the Early Permian and as the Neo-Tethys Ocean opened behind it, during the Permian, the Paleo-Tethys closed in front of it. Because the different chunks of Cimmeria drifted northward at different rates, a Meso-Tethys Ocean formed between the different fragments during the Cisuralian. Cimmeria rifted off Gondwana from east to west, from Australia to the eastern Mediterranean. It stretched across several latitudes and spanned a wide range of climatic zones.

<i>Pampaphoneus</i> Extinct genus of therapsids

Pampaphoneus is an extinct genus of carnivorous dinocephalian therapsid belonging to the family Anteosauridae. It lived 268 to 265 million years ago during the Wordian age of the Guadalupian period in what is now Brazil. Pampaphoneus is known by an almost complete skull with the lower jaw still articulated, discovered on the lands of the Boqueirão Farm, near the city of São Gabriel, in the state of Rio Grande do Sul. A second specimen from the same locality was reported in 2019 and 2020 but has not yet been described. It is composed of a skull associated with postcranial remains. It is the first South American species of dinocephalian to have been described. The group was previously known in South America only by a few isolated teeth and a jaw fragment reported in 2000 in the same region of Brazil. Phylogenetic analysis conducted by Cisneros and colleagues reveals that Pampaphoneus is closely related to anteosaurs from European Russia, indicating a closer faunal relationship between South America and Eastern Europe than previously thought, thus promoting a Pangea B continental reconstruction.

<span class="mw-page-title-main">Word Formation</span> Ecosystem

The Word Formation is a geologic formation in Texas. It preserves fossils dating back to the Permian period. It is probably named for the Old Word Ranch in the Glass Mountains of Brewster County.

The Coyote Butte Limestone (OR085) is a geologic formation in Oregon. It preserves fossils dating back to the Sakmarian to Kungurian stages of the Permian period, spanning an estimated 23 million years. The formation occurs in isolated buttes to the north; Triangulation Hill, and south; type locality and name giver Coyote Butte and Tuckers Butte, on either side of the Grindstone and Twelvemile Creeks in Crook County, Oregon.

The Karabaglyar Formation is a geologic formation in Armenia and Azerbaijan. It preserves fossils dated to the Changhsingian age of the Permian period and the Induan age of the Triassic period, straddling the Permian-Triassic boundary.

The Dovžan Gorge Formation is a geologic formation in Slovenia. It preserves fossils dating back to the Permian period. The formation is named after the Dovžan Gorge.

<span class="mw-page-title-main">Trogkofel Formation</span> Geologic formation in Austria, Slovenia and Italy

The Trogkofel Formation is a geologic formation in Austria, Slovenia and Italy. It preserves fossils dating back to the Sakmarian to Artinskian stages of the Permian period.

<i>Alierasaurus</i> Extinct genus of synapsids

Alierasaurus is an extinct genus of caseid synapsid that lived during the early Middle Permian (Roadian) in what is now Sardinia. It is represented by a single species, the type species Alierasaurus ronchii. Known from a very large partial skeleton found within the Cala del Vino Formation, Alierasaurus is one of the largest known caseids. It closely resembles Cotylorhynchus, another giant caseid from the San Angelo Formation in Texas. The dimensions of the preserved foot elements and caudal vertebrae suggest an estimated total length of about 6 or 7 m for Alierasaurus. In fact, the only anatomical features that differ between Alierasaurus and Cotylorhynchus are found in the bones of the feet; Alierasaurus has a longer and thinner fourth metatarsal and it has ungual bones at the tips of the toes that are pointed and claw-like rather than flattened as in other caseids. Alierasaurus and Cotylorhynchus both have very wide, barrel-shaped rib cages indicating that they were herbivores that fed primarily on high-fiber plant material.

<span class="mw-page-title-main">Hiló Formation</span> Geological formation in the Colombian Andes

The Hiló Formation is a geological formation of the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The predominantly shale formation dates to the Middle Cretaceous period; Late Albian to Early Cenomanian epochs and has a measured thickness at its type section of 470 metres (1,540 ft). The fossiliferous formation has provided a great abundance of ammonites and other marine species.

The geology of Iraq includes thick sequences of marine and continental sedimentary rocks over poorly understood basement rock, at the junction of the Arabian Plate, the Anatolian Plate, and the Iranian Plate.

Septopora is an extinct genus of bryozoan belonging to the order Fenestrida. It has been found in Pennsylvanian to Permian beds in North America, South America, Australia, and southwest and east Asia.

<i>Marginifera</i> Extinct genus of brachiopod

Marginifera is an extinct genus of brachiopod belonging to the order Productida. Specimens have been found in Carboniferous to Triassic beds in Asia, Europe, Madagascar, and North America.

Eostaffella is an extinct genus of fusulinid belonging to the family Eostaffellidae. Specimens of the genus have been found in Carboniferous to Permian beds in Europe, Asia, and North America.

<i>Lalieudorhynchus</i> Extinct genus of synapsids

Lalieudorhynchus is an extinct genus of caseid synapsids that lived during the Guadalupian in what is now the south of France. The genus is only known by its type species, Lalieudorhynchus gandi, which was named in 2022 by Ralf Werneburg, Frederik Spindler, Jocelyn Falconnet, Jean-Sébastien Steyer, Monique Vianey-Liaud, and Joerg W. Schneider. Lalieudorhynchus is represented by a partial postcranial skeleton discovered in the Lodève basin in the central part of the Hérault department in the Occitanie region. It belongs to an individual measuring approximately 3.75 m (12.3 ft) in length. The degree of ossification of its bones, however, indicates that it was a late juvenile or still growing young adult. Based on the internal structure of its bones, the describing authors interpreted Lalieudorhynchus as a semiaquatic animal that may have had a lifestyle similar to that of hippopotamus, spending part of its time in water but returning to land for food, though the idea that caseids were semi-aquatic has been previously contested by other authors. It is geologically one of the youngest known representatives of the caseids. The phylogenetic analysis proposed by Werneburg and colleagues identified Lalieudorhynchus as a derived caseid closely related to the North American species "Cotylorhynchus" hancocki.

References

  1. 1 2 3 Gnishik Formation in the Paleobiology Database
  2. Leven, 1998, p.302
  3. 1 2 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. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 Ruzhentsev & Sarycheva
  9. 1 2 3 4 5 6 7 8 9 10 Stepanov et al., 1969
  10. 1 2 3 4 Kropatcheva, 1999
  11. 1 2 3 4 5 6 7 8 9 10 Kotlyar et al., 1989
  12. 1 2 3 4 5 6 7 8 9 10 11 Morozova, 1970
  13. 1 2 3 4 Ezaki, 1991
  14. Stukalina, 1999
  15. 1 2 3 4 5 6 Nakamura & Golshani, 1981
  16. 1 2 3 Shishova, 1964
  17. Gennari & Rettori, 2019

Bibliography

Geology
Paleontology