Yangikazgan Formation

Yangikazgan Fm

Period:

Silurian

Age Interval:

Llandovery, K9a

Province:
Kyzylkum Region

Type Locality and Naming

Along the Yangikazgan collective farm, Kuldjuktau Mountains, Central Kyzylkum. Ya.B. Aysanov et al. in 1967 (44, p. 19-20).

Synonym: Yangikazganskaya Suite, Янгиказганская св.

Lithology and Thickness

Divided into five members.

First (thickness 50m) - light gray, fine-crystalline, vaguely stratified, detrital limestones;

Second (thickness 2530m) - clayey, organogenic, light gray, massive limestones;

Third (thickness 33m) - layered, coarse-grained, crinoidal limestones with abundant organic remains;

Fourth (thickness 80m) - light gray, unevenly grained, nodular, massive, vaguely stratified, sometimes clastic, limestones;

Fifth (thickness 330m) - light and gray, massive, vaguely stratified, less often striped, marbled limestones.

Lithology Pattern:

Limestone

Relationships and Distribution

Lower contact

Along the gradual transition, it lies conformably on the rocks of the upper Ordovician

Upper contact

It is also overlain by the Wenlock deposits (44; Aysanov et al., 1984).

Regional extent

Eastern and western parts, as well as the northern slope of the Kuldyktau Mountains. Stratotype in the area of the Yangikazgan village.

GeoJSON

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Fossils

Numerous organic remains of tabulates - Palaeofavosites ex gr. maximus Tehern., P. alveolaris (Goldf.), P. raikuelaensis Sok., Mesofavosites cf. verus Lel. and others, brachiopods - Pentamerus ex gr. oblongus Sow., P. ex gr. magianicus Men., Retziella cf. antiqua Men., Eospirifer radiatus Sow.; trilobites - Eophacops cf. quadrilinaetus (Angelin) and others; crinoids Bystrowicrinus sp., Desmidacrinus sp. and others.

Age

The Llandovery age is established by numerous organic remains of tabulates. It belongs to the Llandovery stage of the lower Silurian. (122; 165; 460).

Age Span:

Beginning stage:

Rhuddanian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

443.07

Ending stage:

Telychian

Fraction up in the ending stage:

1.0

Ending date (Ma):

432.93

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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