Ayutor Formation

Ayutor Fm

Period:

Ordovician

Age Interval:

Late Ordovician-Early Silurian, CK4

Province:
Chatkal-Kuramin Region

Type Locality and Naming

Along the Ayutor River, Talas Range. A.F.Stepanenko, 1958 (437, pp. 62, 64; 441, p. 49). Stratotype along the Ayutor River.

Synonym: Author's Suite, Аюторская св.

Lithology and Thickness

Lower part of the suite (450-500m) - polymictic sandstones with rare siltstone layers, clayey and siliceous-clayey shales, lenses of gravelites and small-pebble conglomerates. Upper part of the suite (up to 500m) - flyschoid interbedding of sandstones, siltstones, clayey shales. Total thickness of the suite is about 1000m.

Lithology Pattern:

Sandstone

Relationships and Distribution

Lower contact

Lower contact with the underlying Beshtor Fm is predominantly conformable, but in some places (Pskem Range, upper reaches of the Chiralmi River) erosion and slight angular unconformity are recorded.

Upper contact

Overlain by the Tyulkubash Fm with a sharp unconformity

Regional extent

Pskem and Sandalash Ranges, southwestern slope of the Talas Range.

GeoJSON

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Fossils

Age

Age is determined by position in the section and correlation with faunally characterized Upper Ordovician sandstone-shale deposits of the Central Tien-Shan (B. Karatau, Dzhubagly). M.A. Akhmedjanov et al. (72) believed that the age of the A. suite could be Late Ordovician-Early Silurian.

Age Span:

Beginning stage:

Sandbian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

458.18

Ending stage:

Telychian

Fraction up in the ending stage:

1.0

Ending date (Ma):

432.93

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)”