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

Guralash Formation

Guralash Fm

Period:

Silurian

Age Interval:

middle Llandovery, N5a

Province:
Nuratau

Type Locality and Naming

Along the Guralash River, Turkestan Range. M.M. Posokhova, A.N. Golikov in 1973, (165, p.51). Stratotype in the Guralashsaya basin.

Synonym: Guralash Suite, Гуралдашская св.

Lithology and Thickness

Represented by two closely similar in composition packages of slates, separated by a 10–12-meter layer of argillites, saturated with rounded phosphorite nodules. Lower part (thickness 220m) - dark gray argillitic slates, containing thin layers of polymictic silicified siltstone (aleurolites). Upper part (thickness140m) - similar slates with layers of silicified quartz siltstone (aleurolites). Thickness of entire formation is 360-370m.

Lithology Pattern:

Claystone

Relationships and Distribution

Lower contact

According to A.A., it lies conformably on the Oibadam-Sil Fm

Upper contact

According to A.A., it is conformably overlain by the Berkutlin Fm

Regional extent

North slope of the eastern part of the Chumkartau Mountains, upper reaches of the Berkyutli and Akkurgan rivers.

GeoJSON

null

Fossils

Contains numerous graptolites - Hedrograptus rectangularis (Mc'Coy), Glyptograptus tamariscus tamariscus (Nich.), Coronograptus gregarius (Lapw.), Pernerograptus revolutus (Kurck.), Demirastrites triangulatus (Harkn.), Diplograptussp., Cystograptus cf. grandis Hundt., characteristic of the lower part of the Middle Llandovery substage.

Age

early Silurian, Llandovery period. (165; 460).

Age Span:

Beginning stage:

Aeronian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

440.49

Ending stage:

Aeronian

Fraction up in the ending stage:

0.5

Ending date (Ma):

439.54

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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