Earth:Starorusskaya Formation

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Starorusskaya Formation
Stratigraphic range: Late Ediacaran
TypeFormation
Sub-unitsSee: Members
UnderliesVasileostrovskaya Formation
OverliesPasha Formation
Thickness44 - 52 m
Lithology
PrimaryArgillite, sandstone, siltstone
OtherConglomerates, clay
Location
CountryNorthwest Russia

The Starorusskaya Formation is an Ediacaran fossiliferous geologic formation found in Northwestern Russia.

Members

The Starorusskaya Formation consists of 3 Members. Every member within the formation contains fossil material.

The members are as follows, listed by ascending age:

  • Lower Member is characterized by clays with sandstone interbeds. There are also greenish-gray to blueish thin-bedded sandy and silty clays, which is replaced in the upper sections of the member by dense greenish-gray clays. There are also light gray quartz sandstones, ranging from fine-medium-grained to coarse-grained, and contain a mixture of gravels. It is up to 16.3 m thick, and contains the microfossils of the formation.[1]
  • Middle Member is composed primarily of clays. This includes dark red clays with thin interbeds of light gray siltstones. Other areas contain gray, thin-bedded silty clays, containing interbeds of fine-gravel and sandstones. It is up to 22 m thick, and contains the least amount of fossils in the formation[1]
  • Upper Member is composed of thin interbedded sandstones, siltstones and clays. The clays are predominately blueish to greenish-gray, which are finely laminated and leafy, containing dark red spots through-out. The sandstones and siltstones are greenish-gray also, with the sandstones being coarse-grained. It is up to 13.4 m thick, and contains the macrofossils of the formation.[1]

Paleoenvironment

From the information gathered from the lithology of the Starorusskaya Formation, its paleoenvironment was most likely a sloped environment either below the wave base or even storm wave base, and was within the photic zone, inferred from the presence of Doushantuophyton lineare, overall suggesting a prodelta environment where organisms could be buried in situ.[1]

Paleobiota

The Starorusskaya Formation contains a number of organisms from the Ediacaran, including unique forms such as Redkinia.[1][2]

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.

incertae sedis

Genus Species Notes Images
Orbisiana[2][1]
  • Orbisiana sp.
  • O. simplex
 Palaeopascichnid organism.
Redkinia[2]
  • R. spinosa
 Rod-like fossils, possible jaw fragments of stem-arthropods.
Cucullus[2]
  • Cucullus sp.
 Tubular organism.

Flora

Genus Species Notes Images
Siphonophycus[1]
  • Siphonophycus sp.
 Filamentous cyanobacteria.
Oscillatoriopsis[1]
  • Oscillatoriopsis sp.
 Filamentous cyanobacteria.
Zinkovioides[1]
  • Zinkovioides sp.
 Filamentous cyanobacteria.
Obruchevella[1]
  • O. parva
 Filamentous cyanobacteria.
Doushantuophyton[2][1]
  • D. lineare
 Branching macroalgae.
Morania[2]
  • M. zinkovi
 Filamentous cyanobacteria.
Chuaria[2]
  • C. circularis
 Enigmatic fossil, possibly synonymous with Tawuia.
Polytrichoides(?)[2]
  • Polytrichoides sp.(?)
 Filamentous algae.

Microorganisms

Genus Species Notes Images
Leiosphaeridia[2][1]
  • Leiosphaeridia sp.
  • L. jacutica
  • L. crassa
  • L. minutissima
  • L. tenuissima
 Acritarch.
Tynnia[1]
  • T. precambrica
 Acritarch.
Tuberculum (Acritarch)[1]
  • T. mamillatum
 Acritarch.
Ceratosphaeridium[3]
  • Ceratosphaeridium sp.
 Acritarch.
Ostiana[3]
  • Ostiana sp.
 Acritarch.
Ceratophyton(?)[3]
  • Ceratophyton sp.(?)
 Acritarch.


See also


References

  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 Golubkova, E. Yu.; Bobrovskiy, I. M.; Kushim, E. A.; Plotkina, Yu. V. (September 2021). "Fossil Organisms of the Redkino Regional Stage of the Upper Vendian of the Northwestern Russian Platform (Leningrad Region)". Paleontological Journal 55 (5): 579–587. doi:10.1134/S0031030121050051. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 Golubkova, E. Yu.; Kushim, E. A.; Kuznetsov, A. B.; Yanovskii, A. S.; Maslov, A. V.; Shvedov, S. D.; Plotkina, Yu. V. (March 2018). "Redkinian Biota of Macroscopic Fossils from the Northwestern East European Platform (South Ladoga Region)". Doklady Earth Sciences 479 (1): 300–304. doi:10.1134/S1028334X18030169. 
  3. ↑ 3.0 3.1 3.2 Golubkova, E. Yu.; Kushim, E. A.; Kuzmenkova, O. F.; Laptsevich, A. G.; Plotkina, Yu. V.; Silivanov, M. O. (December 2023). "Stratigraphic Distribution of Fossil Organisms in the Upper Vendian Deposits of the Central and Southwestern Regions of the East European Platform". Paleontological Journal 57 (S3): S211–S236. doi:10.1134/S0031030124600124. 



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