Neogene

Paleogene

Cretaceous

Jurassic

Triassic

Permian

Carboniferous

Devonian

Silurian

Ordovician

Cambrian

Neoproterozoic

Mesoproterozoic

Paleoproterozoic

Main source = Abduazimova, Z.M. (Ed.), 2001. Stratigraphic Dictionary of Uzbekistan. IMR (Institute of Mineral Resources), Tashkent, 580 pp. (In Russian) Translated to English by the GeoGPT group, Zhejiang Lab, Hangzhou, China--see About

Altyaul Formation

Altyaul Fm

Period:

Ordovician

Age Interval:

Middle-Upper Ordovician, Z5

Province:
Zarafshan-N.Gissar

Type Locality and Naming

Along the Altyaul stream, northeastern Zirabulak Mountains. E.I. Barkovskaya, E.S. Sorokin in 1963 (88, pp. 27-28).

Synonym: Altyaul Suite, Алтыаульская св.

Lithology and Thickness

Clayey, clayey-mica, and carbonaceous clayey slates with layers of siltstones, sandstones, gravelites, conglomerates, limestones, rhyolites, and their tuffs. Thickness varies among different researchers - from 420 to 2500m (44; 72; 88; 122; 165; 460).

Lithology Pattern:

Sandy_claystone

Relationships and Distribution

Lower contact

Lower contact is unknown

Upper contact

Upper contact is conformable, with a gradual transition to the Yarmanchin Fm (Korsakov et al., 1993).

Regional extent

Zirabulak Mountains, basins of the Kochkarly, Ovkhana, Altyaul, Napas, Turita, and Kyrktau rivers. It is correlated with the Kazakasuy Fm in Kuldzhuktau (44).

GeoJSON

null

Fossils

Contains brachiopods - Strophonema sp., Orthidae sp.; algae - Dimorphosiphon rectangulare Hold. and others; corals - Lyopora regularia Kim., Catenipora sp., Agetolites asiaticus Kim and others; trilobites - Pseudomera sp.; graptolites - Dictyonema ex gr. volchovense Obut. (72; 88).

Age

Based on fauna and correlation with coeval formations, it is assigned to the Middle-Upper Ordovician.

Age Span:

Beginning stage:

Darriwilian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

469.42

Ending stage:

Hirnantian

Fraction up in the ending stage:

1.0

Ending date (Ma):

443.07

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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