Shorashuy Formation

Shorashuy Fm

Period:

Proterozoic

Age Interval:

Precambrian (Vendian?), CK4

Province:
Chatkal-Kuramin Region

Type Locality and Naming

Along the Shorash River. A.F. Stepanenko in 1956 (437, pp.59-66) from the composition of the Karakasmak suite.

Synonym: Shorashuyskaya Suite, Шорашуйская св.

Lithology and Thickness

Lower sub-suite - tilloid-like conglomerates from unsorted rocks with sandy-silty-clayey matrix, in which "floating" pebbles and boulders (up to 1.5 m in diameter) of various crystalline and metamorphic slates, granitoids, carbonates, effusives, siliceous slates. Thickness 150-350m. These conglomerates were distinguished by L.I. Turbin (475) as an independent Ayakterek suite. Upper sub-suite (or Shorashuy suite, Along L.I. Turbin) - rhythmic flysch-like alternation of polymictic or quartz sandstones, siltstones, clayey and phyllitic slates. Thickness 75-600m. Total thickness of the suite is about 900m.

Lithology Pattern:

Sandstone

Relationships and Distribution

Lower contact

Between sub-suites, the contact is conformable. Shorashuy Fm overlies the Uzunbulak and Mursash suites (Kyrgyzstan) in some places with a sharp contact without noticeable signs of interruption, in others - with local erosion.

Upper contact

With a sharp contact, it is overlain by the Sandalash Fm.

Regional extent

Sandalash and Pskem Ridges, southwestern slope of the Talas Ridge, interfluve of Chonach-Karaterek, northern slope of the Chatkal Ridge. Lower sub-suite is correlated with the Jetymtau, and upper - with the Jakbaity suite of the Vendian of Kyrgyzstan. It is not excluded that tilloid-like conglomerates, attributed to the lower sub-suite, in some areas are equivalent to the upper tilloids of the Jakbolot or Baykonur Fm of Kazakhstan.

GeoJSON

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Fossils

Age

Precambrian age is determined by the overlying deposits of the faunally characterized Sandalash suite of the Cambrian-Ordovician. The fact that Shorashuy Fm is not older than the Vendian is evidenced by the finds of IV (Yudomian) complex of microphytoliths in carbonate clasts enclosed in the rocks of the suite (459).

Age Span:

Beginning stage:

Ediacaran

Fraction up in beginning stage:

0.0

Beginning date (Ma):

635.00

Ending stage:

Ediacaran

Fraction up in the ending stage:

1.0

Ending date (Ma):

538.80

Depositional setting

Depositional pattern:

Additional Information

Compiler:

V.V. Mikhailov – In: GeoGPT translation of: “Abduazimova, Z.M. (Ed.), 2001. Stratigraphic Dictionary of Uzbekistan. IMR (Institute of Mineral Resources), Tashkent, 580 pp. (In Russian)”