Madygen Formation

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Madygen Formation
Stratigraphic range: Carnian
~235–222 Ma
TypeGeological formation
OverliesCambrian to Carboniferous rocks
Thickness560 m (1,840 ft)
Lithology
PrimaryConglomerate, sandstone
OtherMudstone
Location
Coordinates40°06′N 70°12′E / 40.1°N 70.2°E / 40.1; 70.2Coordinates: 40°06′N 70°12′E / 40.1°N 70.2°E / 40.1; 70.2
Approximate paleocoordinates41°12′N 60°36′E / 41.2°N 60.6°E / 41.2; 60.6
RegionBatken & Osh Regions
Country Kyrgyzstan
 Tajikistan
 Uzbekistan
ExtentFergana Valley & Range
Type section
Named forMadygen village
Named byEvgeny A. Kochnev
Madygen Formation is located in Kyrgyzstan
Madygen Formation
Madygen Formation (Kyrgyzstan)

The Madygen Formation (Russian: Madygen Svita) is a Late Triassic (Carnian) geologic formation and Lagerstätte in the Batken and Osh Regions of western Kyrgyzstan, with minor outcrops in neighboring Tajikistan and Uzbekistan. The conglomerates, sandstones and mudstones of the 560 m (1,840 ft) thick formation were deposited in terrestrial lacustrine, alluvial, fluvial and deltaic environments.

The formation, extending across the Fergana Valley and Fergana Range, is unique for Central Asia, as it represents one of the few known continental deposits and the Madygen Formation is renowned for the preservation of more than 20,000 fossil insects, making it one of the richest Triassic Lagerstätten in the world. Other vertebrate fossils as fish, amphibians, reptiles and synapsids have been recovered from the formation too, as well as minor fossil flora.

The lake sediments of the Lagerstätte provided fossil cartilaginous fishes and their egg capsules and unusual Triassic reptiles like Sharovipteryx and Longisquama.[1][2] The wide diversity of insect fossils was first discovered in the 1960s and first described by Russian paleontologist Aleksandr Sharov, with a notable example being Gigatitan.[3]

Description[edit]

Paleogeography of the Late Triassic, around 230 Ma. The Madygen Formation was deposited north of the Paleo-Tethys ocean.

The Madygen Formation is a 560 metres (1,840 ft)[4] thick succession of predominantly siliciclastic rocks accumulated in a tectonically induced basin, covering parts of the Fergana Range and Fergana Valley of Kyrgyzstan with minor outcrops in Tajikistan and Uzbekistan.[5] The Late Triassic layers rest on top of Paleozoic basement with local Permo-Triassic molasse sediments. The section consists of mudstones, sandstones, conglomerates and fanglomerates. This wide variety of siliciclastic rocks reflects the complex spatial and temporal pattern of depositional sub-environments including alluvial fans, sandflats, swamps, back-swamp areas, and littoral to profundal lake zones. The fluvio-lacustrine deposits of the Madygen Formation belong to one of only a few occurrences of continental Triassic beds in Central Asia.[6]

The formation was deposited during the Carnian Pluvial Event (CPE), a global humid event leading to high extinction levels of various groups globally. The CPE led to anoxic conditions, most notably in the South China Block. The area where the Madygen Formation was deposited formed part of the Cimmerian microcontinent, a slab of crust that collided with Laurasia during the Cimmerian orogeny in later Mesozoic times. This orogeny led to the disappearance of the Paleo-Tethys Ocean.

Petroleum geology[edit]

The formation grades from bottom to top from alluvial to fluvial into a thick succession of lacustrine mudstones, followed by an alluvial package, on top of which lacustrine, fluvial, deltaic and alluvial layers were deposited.[5]

The hydrocarbon potential of samples of the Madygen Formation ranges from poor to excellent. The sediments containing more than 0.5% Total Organic Carbon (TOC) may be regarded as sources of gaseous hydrocarbons rather than of oil.[7] The Hydrogen Index (HI) of outcrop samples reaches 100 and the maximum recorded maturity (Ro) is 0.8.[8]

Paleontological significance[edit]

During the 1960s, Russian paleontologists recovered an unusually rich fossil content in the type strata of the Madygen Formation, including abundant macrophytes, more than 20,000 insect remains[9] and unique small reptiles with well preserved soft tissue.[6] Spirorbis-like polychaete worm tubes, crustaceans (ostracods, kazacharthrans, malacostraca), freshwater pelecypods and gastropods are known from shallow to deeper lake environments. Non-aquatic insects are among the most common fossil remains of the Madygen Formation. These include representatives of the orders Ephemeroptera, Odonata, Notoptera, Blattodea, Titanoptera, Ensifera, Caelifera, Rhynchota, Auchenorrhyncha, Stenorrhyncha, Coleoptera, Hymenoptera, Trichoptera and Diptera. Traces of insect larvae are preserved in near-shore lake deposits.[10]

Fish remains mostly represent endemic genera assigned to the actinopterygian families Evenkiidae (Oshia), Palaeoniscidae (Ferganiscus, Sixtelia) and Megaperleidus and Alvinia. The actinopterygian Saurichthys and the dipnoan Asiatoceratodus are cosmopolitan taxa also recorded in the Madygen Formation. Two distinctive elasmobranch egg capsule types, i.e. Palaeoxyris, indicating a small Lissodus- or Lonchidion-like hybodont shark and an indeterminate capsule type, imply the presence of two different elasmobranch species which used the freshwater environments of the Madygen Formation as spawning grounds. Tetrapods are known from a probably larval urodelan (Triassurus), a small procynosuchid cynodont (Madysaurus), a gliding reptile (Sharovipteryx) and the enigmatic diapsid Longisquama.[10]

Fossil content[edit]

Amphibians[edit]

Genus Species Material Notes Images
Madygenerpeton M. pustulatus A chroniosuchid reptiliomorph[11]
Madygenerpeton pustulatus.jpg
Triassurus T. sixtelae A possible early caudate (salamander) known from fossil larvae[12]
Triassurus NT.png

Reptiles[edit]

Genus Species Material Notes Images
Kyrgyzsaurus K. bukhanchenkoi A single specimen preserving the front half of a skeleton and scale impressions A drepanosaur[13]
Kyrgyzsaurus NT.png
Longisquama L. insignis A reptile with an elongated row of scales along its back[14]
Longisquama BW.jpg
Sharovipteryx S. mirabilis A gliding prolacertiform[15]
Sharovipteryx.jpg

Synapsids[edit]

Genus Species Material Notes Images
Madysaurus M. sharovi A cynodont[16]
Madysaurus NT.png

Cartilaginous fishes[edit]

Genus Species Material Notes Images
Fayolia F. sharovi An egg capsule likely belonging to a xenacanthid[1]
Lonchidion L. ferganensis Teeth and egg capsules A hybodontid shark[1]
Palaeoxyris P. alterna Teeth and egg capsules A hybodontid shark[1]

Fishes[edit]

The following fish fossils were found in the formation:[10][17][18]

Genus Species Images
Alvinia Alvinia serrata
Ferganiscus Ferganiscus osteolepis
Megaperleidus Megaperleidus lissolepis
Oshia Oshia ferganica
Saurichthys Saurichthys orientalis
Saurichthys.JPG
Sixtelia Sixtelia asiatica

Arthropods[edit]

Genus Species Description Notes Images
Gigatitan G. extensus A mantis-like predator with a wingspan of approximately 33 centimetres (13 in). It is the type genus of the family Gigatitanidae. [19]
Gigatitan vulgaris.jpg
G. magnificus
G. ovatus
G. similis
G. vulgaris
Aiban A. kichineis A member of Cnemidolestida/Cnemidolestodea (an extinct group of insects of uncertain phylogenetic placement, might be related to plecopterans or orthopterans) belonging to the family Sylvabestiidae [20]
Batkentak B. intactus A member of Grylloblattida/Eoblattida belonging to the family Daldubidae [21]
Chubakka C. madygensis A madygelline xyelid sawfly [22]
Locustoblattina L. marginata A member of Eoblattida belonging to the family Mesorthopteridae [23]
L. segmentata
Madygella M. aristovi A madygelline xyelid sawfly [22]
M. bashkuevi
M. kurochkini
M. levivenosa
Nestorembia N. novojilovi A webspinner belonging to the family Alexarasniidae [24]
N. shcherbakovi [23]
Paratitan P. reliquia A right wing belonging to Neopterygota [25]
Sharovites S. alexanderi A member of Grylloblattida/Eoblattida, belonging to the family Mesorthopteridae [26]
Shurabia S. tanga A member of Polyneoptera belonging to the group Reculida and the family Geinitziidae [27]
Guillermia G. lecticula [28]
Madygenorhynchus M. multifidus
Thaumatomerope T. sogdiana
Prochoristella P. longa
Dilemmala D. specula
Sacvoyagea S. ventrosa
Nonescyta N. mala
Maguviopsis M. kotchnevi
Falcarta F. bella
Krendelia K. ansata
Cuanoma C. protracta
Phyllotexta P. latens
Sitechka S. perforata
Tingiopsis T. reticulata
Pelorisca P. connectens
Xamenophlebia X. ornata
Thuringoblatta T. sogdianensis
Sacvoyagea S. ventrosa
Protoblattogryllus P. variabilis [29]
Megablattogryllus M. austerus
M. pinguis
Metakhosara M. sharovi
Batkentak B. intactus
Austroidelia A. asiatica
A. nervosa
Mesoidelia M. faceta
Parastenaropodites P. fluxa
P. longiuscula
Baharellus B. madygensis
Anoblattogryllus A. fundatus
Costatoviblatta C. aenigmatosa
C. conjuncta
Paratitan P. reductus
Prototitan P. sharovi
Mesoedischia M. obliqua
Paragryllavus P. curvatus
Zagryllavus Z. elongatus
Hagloedischia H. primitiva
Voliopus V. ancestralis
Euvoliopus E. giganteus
Macrovoliopus M. declivis
Paravoliopus P. dorsalis
Voliopellus V. latus
Triassaga T. angusta
Zamaraga Z. reticulata
Haglomorpha H. martynovi
Modihagla M. ovalis
Dulcihagla D. mistshenkoi
Lyrohagla L. uvarovi
Sonohagla S. curta
Tinnihagla T. zeuneri
Dolichohagla D. longa
Locustavus L. problematicus
L. intermedius
L. minutus
Miolocustavus M. reductus
Brevilocustavus B. distinctus
Fritaniopsis F. brevicaulis
Sogdoblatta S. nana
S. porrecta
Thuringoblatta T. sogdianensis
Xiphopterum X. sharovi
Sharovoplana S. parallelica
Triassophasma T. intermedium
T. pusillum
Prochresmoda P. parva
Nestorembia N. novojilovi
Madygenophlebia M. bella
M. nana
Gorochovia G. individua
G. minuta
G. bifurca
Gorochoviella G. conjuncta
Pseudoliomopterites P. obscurus
Ideliopsina I. nana
I. stupenda
I. ornata
Pseudoshurabia P. pallidula
Peltosyne P. varyvrosa
Ofthalmopeltos O. synkritos
Obrienia O. illaetabilis
Triassochorista T. kirgizica
Parachorista P. arguta
P. immota
Choristopanorpa C. temperata
Thaumatomerope T. oligoneura
T. sogdiana
Mesageta M. rieki
Liassochorista L. utilis
Agetopanorpa A. deceptoria
Prochoristella P. longa
Mesopsyche M. ordinata
M. justa
M. tortiva
Psychotipa P. predicta
Vymrhyphus V. tuomikoskii
Gnomusca G. molecula
Asiocula A. lima
Fasolinka F. beckermigdisovae
Fulgobole F. evansi
Scytachile S. emeljanovi
Serpentivena S. tigrina
Coccavus C. supercubitus
Kennedya K. carpenteri
K. gracilis
Batkenia B. pusilla
Paurophlebia P. lepida
P. angusta
Neritophlebia N. elegans
N. vicina
N. longa
Mixophlebia M. mixta
Cyrtophlebia C. sinuosa
Zygophlebia Z. ramosa
Reisia R. sogdiana
Shurabia S. serrata
Mesoblattogryllus M. intermedius [19]
Protoblattogryllus P. asiaticus
P. variabilis
Megablattogryllus M. austerus
M. magister
Megakhosarodes M. paulivenosus
Metakhosara M. sharovi
Austroidelia A. asiatica
A. nervosa
Mesoidelia M. ignorata
M. faceta
Parastenaropodites P. longiuscula
P. fluxa
Locustoblattina L. segmentata
Dorniella D. primitiva
Baharellus B. madygensis
Baharellinus B. dimidiatus
B. pectinatus
Costatoviblatta C. aenigmatosa
C. similis
Ferganamadygenia F. plicata
Paratitan P. libelluloides
P. venosus
P. intermedius
P. latispeculum
P. modestus
Mesotitanodes M. tillyardi
M. similis
Mesotitan M. primitivus
Provitimia P. pectinata
Proshiella P. ramivenosa
Mesoedischia M. madygenica
Gryllacrimima G. perfecta
Madygenia M. orientalis
M. ovalis
Kashgarlimahmutia K. reducta
Proxenopterum P. primitivum
Axenopterum A. venosum
Ferganopterus F. clarus
Ferganopterodes F. reductus
Pteroferganodes P. rieki
Tuphella T. rohdendorfi
T. sharovi
Platyvoliopus P. maximus
Stenovoliopus S. elongatus
Zavoliopus Z. densus
Turkestania T. deviata
Triassaga T. tshorkuphlebioides
Eumaraga E. madygenica
Hagloptera H. intermedia
Archihagla A. tenuis
Proisfaroptera P. martynovi
Protshorkuphlebia P. triassica
P. similis
Dulcihagla D. beybienkoi
Lyrohagla L. pravdini
L. decipiens
Sonohagla S. saussurei
S. chopardi
Microhagla M. minuta
Dinohagla D. corrugata
Adzhajloutshella A. plana
Locustavus L. lanceolatus
L. problematicus
L. intermedius
L. deformatus
L. minutus
Dicronemoura D. acaulis
Tritaniella T. mera
T. synneura
Fritaniopsis F. brevicaulis
F. remota
Sogdoblatta S. nana
Thuringoblatta T. sogdianensis
Subioblatta S. madygenica
Xiphopterum X. curvatum
Sharovoplana S. affinis
Triassophasma T. brevipoda
T. intermedium
T. minutissimum
Prochresmoda P. minuta
Madygenophlebia M. bella
M. primitiva
Micromadygenophlebia M. obscura
Gorochovia G. individua
Ideliopsina I. nana
I. ornata
Madygenidelia M. conjuncta
Pseudoshurabia P. pallidula
Hadeocoleus H. gigas
H. pelopius
H. catachtonius
Triassocoleus T. tortulosus
Salebroferus S. confragosus
S. asper
Schizophoroides S. rugosus
Thnesidius T. xyphophorus
Catabrycus C. hoplites
Triaplus T. laticoxa
Dolichosyne D. rostrata
Ademosyne A. kirghizica
Cephalosyne C. capitata
Cupesia C. sepulta
Notocupes N. laticella
N. rostratus
N. tenuis
Cladochorista C. multivenosa
Prophilopotamus P. asiaticus
Triassochorista T. kirgizica
Parachorista P. asiatica
P. multivena
P. arguta
P. sana
Mesageta M. pertrita
M. ignava
Agetopanorpa A. consueta
Prochoristella P. longa
Mesopsyche M. shcherbakovi
M. justa
M. gentica
Psychotipa P. depicta
Nadiptera N. pulchella
Oryctoxyela O. anomala
Madygenius M. primitivus
Ferganoxyela F. sogdiana
F. destructa
Triassoxyela T. orycta
Nevicia N. imitans
Asiocula A. lima
Phyllotexta P. latens
Fulgobole F. evansi
Scytachile S. cf. emeljanovi
Tingiopsis T. reticulata
Coccavus C. supercubitus
Permonka P. unica
P. triassica
Permosialis P. triassica
Triassolestodes T. asiaticus
Terskeja T. pumilio
T. tenuis
Paurophlebia P. lepida
Cladophlebia C. parvula
C. brevis
Nonymophlebia N. venosa
Neritophlebia N. longa
Triadophlebia T. madygenica
T. minuta
T. magna
T. honesta
T. modica
Mitophlebia M. enormis
Xamenophlebia X. ornata
Zygophlebiella Z. curta
Mixophlebia M. mixta
Shurabia S. minuta
S. ferganensis
S. anomala
Maguviopsis M. kotchnevi [30]
Tingiopsis T. reticulata
Dolichosyne D. confragosa [31]
Rhabdocupes R. baculatus
Salebroferus S. confragosus
Asiocula A. lima [32]
Blattomerope B. polyneura
Cuanoma C. protracta
Fasolinka F. beckermigdisovae
Kirgizichorista K. larvata
Krendelia K. ansata
Lithocupes L. incertus
Maguviopsis M. kotchnevi
Megakhosarodes M. paulivenosus
Nonescyta N. mala
Obrienia O. ingurgata
O. kuscheli
Panorpaenigma P. aemulum
Parachorista P. religiosa
Phyllotexta P. latens
Sacvoyagea S. ventrosa
Siberioperla S. ovalis
Sitechka S. perforata
Sogdodromeus S. altus
Triaplus T. macroplatus
Megakhosarodes M. paulivenosus [33]
Choristopanorpa C. opinata [34]
Dzhajloutshella D. arcanum
Kuperwoodia K. benefica
Macrocatinius M. brachycephalus
Neotuphella N. minor
Pesus P. prognathus
Mesageta M. gigantea [35]
M. rieki [34]
Triassoxya T. novozhilovi [36]

Flora[edit]

Genus Species Description Notes Images
Mesenteriophyllum M. kotschnevii [14]
Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Insect fauna correlations[edit]

Progonocimicidae found in the formation are also recorded in the Carnian Los Rastros Formation of Argentina, the Norian Blackstone and Mount Crosby Formations of Australia, and the Norian to Rhaetian Tologoi Formation of Kazakhstan.[37] Permochoristidae are also known from the Carnian Potrerillos and Cacheuta Formations of Argentina, Huangshanjie Formation of China, the Norian Blackstone and Mount Crosby Formations of Australia; the Norian to Rhaetian Tologoi Formation of Kazakhstan, the Sinemurian Dzhil Formation of Kyrgyzstan and the Toarcian Posidonia Shale of Germany.[38]

Orthophlebia had a relatively broad distribution in the Late Triassic as it is also found in the Sinemurian Badaowan Formation of China and Dzhil Formation of Kyrgyzstan, the Pliensbachian Makarova Formation of Russia and Sulyukta Formation of Tajikistan; the Toarcian Whitby Mudstone Formation of England, Posidonia Shale of Germany, and Cheremkhovo Formation of Russia, and the Early Jurassic Kushmurun Formation of Kazakhstan.[39]

Haglidae were also recorded in the Koldzat and Tologoi Formations of Kazakhstan, in the Carnian Cacheutá Formation of Argentina, the Carnian to Norian Molteno Formation of South Africa and Lesotho, and the Norian Mount Crosby Formation of Australia.[40]

See also[edit]

Other Central Asian Lagerstätten

References[edit]

  1. ^ a b c d Fischer et al., 2011
  2. ^ Unwin et al., 2003, pp.177-186
  3. ^ Shcherbakov, 2008
  4. ^ Fischer et al., 2018, p.25
  5. ^ a b Berner et al., 2009, p.2
  6. ^ a b Fischer et al., 2007, p.42
  7. ^ Berner et al., 2009, p.5
  8. ^ Berner et al., 2009, p.6
  9. ^ Kelly, 2018, p.62
  10. ^ a b c Voigt et al., 2007, p.162
  11. ^ Schoch et al., 2010
  12. ^ Schoch et al., 2020
  13. ^ Alifanov & Kurochkin, 2011
  14. ^ a b Buchwitz & Voigt, 2012
  15. ^ Sharov, 1971
  16. ^ Tatarinov, 2005
  17. ^ Kogan et al., 2009, p.142
  18. ^ Franeck et al., 2013, p.54
  19. ^ a b Sharov, 1968
  20. ^ Aristov, 2018
  21. ^ Aristov, 2015
  22. ^ a b Kopylov, 2014
  23. ^ a b Aristov, 2017
  24. ^ Shcherbakov, 2015
  25. ^ Béthoux et al., 2010, p.9
  26. ^ Aristov & Storozhenko, 2013
  27. ^ Aristov & Sukatcheva, 2018
  28. ^ Shcherbakov, 2011
  29. ^ Aristov et al., 2009
  30. ^ Becker-Migdisova, 1953
  31. ^ Ponomarenko, 1969
  32. ^ Arnoldi et al., 1977
  33. ^ Storozhenko, 1993
  34. ^ a b Shcherbakov et al., 1995
  35. ^ Novokshonov, 1997
  36. ^ Gorochov, 2005
  37. ^ Kelly, 2018, p.190
  38. ^ Kelly, 2018, p.186
  39. ^ Kelly, 2018, p.185
  40. ^ Kelly, 2018, p.182

Bibliography[edit]