Starorusskaya Formation


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.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 formationUpper 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.

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.

Paleobiota

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

''incertae sedis''

GenusSpeciesNotesImages
Orbisiana
Palaeopascichnid organism.
Redkinia
  • R. spinosa
    		• Rod-like fossils, possible jaw fragments of stem-arthropods.
    Cucullus
  • Cucullus sp.
    		• Tubular organism.

    Flora

    GenusSpeciesNotesImages
    Siphonophycus
    • Siphonophycus sp.
    		Filamentous cyanobacteria.
    Oscillatoriopsis
  • Oscillatoriopsis sp.
    		• Filamentous cyanobacteria.
    Zinkovioides
  • Zinkovioides sp.
    		• Filamentous cyanobacteria.
    Obruchevella
  • O. parva
    		• Filamentous cyanobacteria.
    Doushantuophyton
  • D. lineare
    		• Branching macroalgae.
    Morania
  • M. zinkovi
    		• Filamentous cyanobacteria.
    Chuaria
  • C. circularis
    		• Enigmatic fossil, possibly synonymous with Tawuia.
    Polytrichoides
  • Polytrichoides sp.
    		• Filamentous algae.

    Microorganisms

    GenusSpeciesNotesImages
    Leiosphaeridia
    		Acritarch.
    Tynnia
  • T. precambrica
    		• Acritarch.
    Tuberculum (Acritarch)
  • T. mamillatum
    		• Acritarch.
    Ceratosphaeridium
  • Ceratosphaeridium sp.
    		• Acritarch.
    Ostiana
  • Ostiana sp.
    		• Acritarch.
    Ceratophyton
  • Ceratophyton sp.
    		• Acritarch.