Madygen Formation
Stratigraphic range: Carnian
~
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; 70.2
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

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

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

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 Bivalves 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

Amphibians

GenusSpeciesMaterialNotesImages
Madygenerpeton M. pustulatus A chroniosuchid reptiliomorph[11]
Triassurus T. sixtelae A possible early caudate (salamander) known from fossil larvae[12]

Reptiles

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

Synapsids

GenusSpeciesMaterialNotesImages
Madysaurus M. sharovi A cynodont[16]

Cartilaginous fishes

GenusSpeciesMaterialNotesImages
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

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

GenusSpeciesImages
AlviniaAlvinia serrata
FerganiscusFerganiscus osteolepis
MegaperleidusMegaperleidus lissolepis
OshiaOshia ferganica
SaurichthysSaurichthys orientalis
SixteliaSixtelia asiatica

Arthropods

GenusSpeciesDescriptionNotesImages
GigatitanG. extensusA mantis-like predator with a wingspan of approximately 33 centimetres (13 in). It is the type genus of the family Gigatitanidae.[19]
G. magnificus
G. ovatus
G. similis
G. vulgaris
AibanA. kichineisA 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]
BatkentakB. intactusA member of Grylloblattida/Eoblattida belonging to the family Daldubidae[21]
ChubakkaC. madygensisA madygelline xyelid sawfly[22]
LocustoblattinaL. marginataA member of Eoblattida belonging to the family Mesorthopteridae[23]
L. segmentata
MadygellaM. aristoviA madygelline xyelid sawfly[22]
M. bashkuevi
M. kurochkini
M. levivenosa
NestorembiaN. novojiloviA webspinner belonging to the family Alexarasniidae[24]
N. shcherbakovi[23]
ParatitanP. reliquiaA right wing belonging to Neopterygota[25]
SharovitesS. alexanderiA member of Grylloblattida/Eoblattida, belonging to the family Mesorthopteridae[26]
ShurabiaS. tangaA member of Polyneoptera belonging to the group Reculida and the family Geinitziidae[27]
GuillermiaG. lecticula[28]
MadygenorhynchusM. multifidus
ThaumatomeropeT. sogdiana
ProchoristellaP. longa
DilemmalaD. specula
SacvoyageaS. ventrosa
NonescytaN. mala
MaguviopsisM. kotchnevi
FalcartaF. bella
KrendeliaK. ansata
CuanomaC. protracta
PhyllotextaP. latens
SitechkaS. perforata
TingiopsisT. reticulata
PeloriscaP. connectens
XamenophlebiaX. ornata
ThuringoblattaT. sogdianensis
SacvoyageaS. ventrosa
ProtoblattogryllusP. variabilis[29]
MegablattogryllusM. austerus
M. pinguis
MetakhosaraM. sharovi
BatkentakB. intactus
AustroideliaA. asiatica
A. nervosa
MesoideliaM. faceta
ParastenaropoditesP. fluxa
P. longiuscula
BaharellusB. madygensis
AnoblattogryllusA. fundatus
CostatoviblattaC. aenigmatosa
C. conjuncta
ParatitanP. reductus
PrototitanP. sharovi
MesoedischiaM. obliqua
ParagryllavusP. curvatus
ZagryllavusZ. elongatus
HagloedischiaH. primitiva
VoliopusV. ancestralis
EuvoliopusE. giganteus
MacrovoliopusM. declivis
ParavoliopusP. dorsalis
VoliopellusV. latus
TriassagaT. angusta
ZamaragaZ. reticulata
HaglomorphaH. martynovi
ModihaglaM. ovalis
DulcihaglaD. mistshenkoi
LyrohaglaL. uvarovi
SonohaglaS. curta
TinnihaglaT. zeuneri
DolichohaglaD. longa
LocustavusL. problematicus
L. intermedius
L. minutus
MiolocustavusM. reductus
BrevilocustavusB. distinctus
FritaniopsisF. brevicaulis
SogdoblattaS. nana
S. porrecta
ThuringoblattaT. sogdianensis
XiphopterumX. sharovi
SharovoplanaS. parallelica
TriassophasmaT. intermedium
T. pusillum
ProchresmodaP. parva
NestorembiaN. novojilovi
MadygenophlebiaM. bella
M. nana
GorochoviaG. individua
G. minuta
G. bifurca
GorochoviellaG. conjuncta
PseudoliomopteritesP. obscurus
IdeliopsinaI. nana
I. stupenda
I. ornata
PseudoshurabiaP. pallidula
PeltosyneP. varyvrosa
OfthalmopeltosO. synkritos
ObrieniaO. illaetabilis
TriassochoristaT. kirgizica
ParachoristaP. arguta
P. immota
ChoristopanorpaC. temperata
ThaumatomeropeT. oligoneura
T. sogdiana
MesagetaM. rieki
LiassochoristaL. utilis
AgetopanorpaA. deceptoria
ProchoristellaP. longa
MesopsycheM. ordinata
M. justa
M. tortiva
PsychotipaP. predicta
VymrhyphusV. tuomikoskii
GnomuscaG. molecula
AsioculaA. lima
FasolinkaF. beckermigdisovae
FulgoboleF. evansi
ScytachileS. emeljanovi
SerpentivenaS. tigrina
CoccavusC. supercubitus
KennedyaK. carpenteri
K. gracilis
BatkeniaB. pusilla
PaurophlebiaP. lepida
P. angusta
NeritophlebiaN. elegans
N. vicina
N. longa
MixophlebiaM. mixta
CyrtophlebiaC. sinuosa
ZygophlebiaZ. ramosa
ReisiaR. sogdiana
ShurabiaS. serrata
MesoblattogryllusM. intermedius[19]
ProtoblattogryllusP. asiaticus
P. variabilis
MegablattogryllusM. austerus
M. magister
MegakhosarodesM. paulivenosus
MetakhosaraM. sharovi
AustroideliaA. asiatica
A. nervosa
MesoideliaM. ignorata
M. faceta
ParastenaropoditesP. longiuscula
P. fluxa
LocustoblattinaL. segmentata
DorniellaD. primitiva
BaharellusB. madygensis
BaharellinusB. dimidiatus
B. pectinatus
CostatoviblattaC. aenigmatosa
C. similis
FerganamadygeniaF. plicata
ParatitanP. libelluloides
P. venosus
P. intermedius
P. latispeculum
P. modestus
MesotitanodesM. tillyardi
M. similis
MesotitanM. primitivus
ProvitimiaP. pectinata
ProshiellaP. ramivenosa
MesoedischiaM. madygenica
GryllacrimimaG. perfecta
MadygeniaM. orientalis
M. ovalis
KashgarlimahmutiaK. reducta
ProxenopterumP. primitivum
AxenopterumA. venosum
FerganopterusF. clarus
FerganopterodesF. reductus
PteroferganodesP. rieki
TuphellaT. rohdendorfi
T. sharovi
PlatyvoliopusP. maximus
StenovoliopusS. elongatus
ZavoliopusZ. densus
TurkestaniaT. deviata
TriassagaT. tshorkuphlebioides
EumaragaE. madygenica
HaglopteraH. intermedia
ArchihaglaA. tenuis
ProisfaropteraP. martynovi
ProtshorkuphlebiaP. triassica
P. similis
DulcihaglaD. beybienkoi
LyrohaglaL. pravdini
L. decipiens
SonohaglaS. saussurei
S. chopardi
MicrohaglaM. minuta
DinohaglaD. corrugata
AdzhajloutshellaA. plana
LocustavusL. lanceolatus
L. problematicus
L. intermedius
L. deformatus
L. minutus
DicronemouraD. acaulis
TritaniellaT. mera
T. synneura
FritaniopsisF. brevicaulis
F. remota
SogdoblattaS. nana
ThuringoblattaT. sogdianensis
SubioblattaS. madygenica
XiphopterumX. curvatum
SharovoplanaS. affinis
TriassophasmaT. brevipoda
T. intermedium
T. minutissimum
ProchresmodaP. minuta
MadygenophlebiaM. bella
M. primitiva
MicromadygenophlebiaM. obscura
GorochoviaG. individua
IdeliopsinaI. nana
I. ornata
MadygenideliaM. conjuncta
PseudoshurabiaP. pallidula
HadeocoleusH. gigas
H. pelopius
H. catachtonius
TriassocoleusT. tortulosus
SalebroferusS. confragosus
S. asper
SchizophoroidesS. rugosus
ThnesidiusT. xyphophorus
CatabrycusC. hoplites
TriaplusT. laticoxa
DolichosyneD. rostrata
AdemosyneA. kirghizica
CephalosyneC. capitata
CupesiaC. sepulta
NotocupesN. laticella
N. rostratus
N. tenuis
CladochoristaC. multivenosa
ProphilopotamusP. asiaticus
TriassochoristaT. kirgizica
ParachoristaP. asiatica
P. multivena
P. arguta
P. sana
MesagetaM. pertrita
M. ignava
AgetopanorpaA. consueta
ProchoristellaP. longa
MesopsycheM. shcherbakovi
M. justa
M. gentica
PsychotipaP. depicta
NadipteraN. pulchella
OryctoxyelaO. anomala
MadygeniusM. primitivus
FerganoxyelaF. sogdiana
F. destructa
TriassoxyelaT. orycta
NeviciaN. imitans
AsioculaA. lima
PhyllotextaP. latens
FulgoboleF. evansi
ScytachileS. cf. emeljanovi
TingiopsisT. reticulata
CoccavusC. supercubitus
PermonkaP. unica
P. triassica
PermosialisP. triassica
TriassolestodesT. asiaticus
TerskejaT. pumilio
T. tenuis
PaurophlebiaP. lepida
CladophlebiaC. parvula
C. brevis
NonymophlebiaN. venosa
NeritophlebiaN. longa
TriadophlebiaT. madygenica
T. minuta
T. magna
T. honesta
T. modica
MitophlebiaM. enormis
XamenophlebiaX. ornata
ZygophlebiellaZ. curta
MixophlebiaM. mixta
ShurabiaS. minuta
S. ferganensis
S. anomala
MaguviopsisM. kotchnevi[30]
TingiopsisT. reticulata
DolichosyneD. confragosa[31]
RhabdocupesR. baculatus
SalebroferusS. confragosus
AsioculaA. lima[32]
BlattomeropeB. polyneura
CuanomaC. protracta
FasolinkaF. beckermigdisovae
KirgizichoristaK. larvata
KrendeliaK. ansata
LithocupesL. incertus
MaguviopsisM. kotchnevi
MegakhosarodesM. paulivenosus
NonescytaN. mala
ObrieniaO. ingurgata
O. kuscheli
PanorpaenigmaP. aemulum
ParachoristaP. religiosa
PhyllotextaP. latens
SacvoyageaS. ventrosa
SiberioperlaS. ovalis
SitechkaS. perforata
SogdodromeusS. altus
TriaplusT. macroplatus
MegakhosarodesM. paulivenosus[33]
ChoristopanorpaC. opinata[34]
DzhajloutshellaD. arcanum
KuperwoodiaK. benefica
MacrocatiniusM. brachycephalus
NeotuphellaN. minor
PesusP. prognathus
MesagetaM. gigantea[35]
M. rieki[34]
TriassoxyaT. novozhilovi[36]

Flora

GenusSpeciesDescriptionNotesImages
MesenteriophyllumM. 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

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

Other Central Asian Lagerstätten

References

  1. 1 2 3 4 Fischer et al., 2011
  2. ↑ Unwin et al., 2003, pp.177-186
  3. ↑ Shcherbakov, 2008
  4. ↑ Fischer et al., 2018, p.25
  5. 1 2 Berner et al., 2009, p.2
  6. 1 2 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. 1 2 3 Voigt et al., 2007, p.162
  11. ↑ Schoch et al., 2010
  12. ↑ Schoch et al., 2020
  13. ↑ Alifanov & Kurochkin, 2011
  14. 1 2 Buchwitz & Voigt, 2012
  15. ↑ Sharov, 1971
  16. ↑ Tatarinov, 2005
  17. ↑ Kogan et al., 2009, p.142
  18. ↑ Franeck et al., 2013, p.54
  19. 1 2 Sharov, 1968
  20. ↑ Aristov, 2018
  21. ↑ Aristov, 2015
  22. 1 2 Kopylov, 2014
  23. 1 2 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. 1 2 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

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