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

Kshtudak Formation

Kshtudak Fm

Period:

Silurian

Age Interval:

Lower-Middle Llandovery, Z3

Province:
Zarafshan-N.Gissar

Type Locality and Naming

Along the Kshudak River, northern slope of the Chumkartau Mountains. A.S. Shadchnev in 1967 (460, pp. 73-74) in the volume of the middle Llandovery part of the Baykungur Suite by M.M. Posokhova. A.S. Shadchnev described the lower part of the suite under the name Lyangar; on the State Geological Map-500 of Uzbekistan (460), the Lyangar Fm is included in the composition of the Kshudak Fm.

Synonym: Kshudak Suite, Кштудинская св.

Lithology and Thickness

Lower part, carbonaceous-siliceous-micaceous, clayey-micaceous shales. Upper part - siliceous shales, siliceous-clayey shales, argillites with layers of sandstones, siltstones, and rarely limestones and jaspers. Thickness: 900m.

Lithology Pattern:

Claystone

Relationships and Distribution

Lower contact

According to A.D. Starshinin, A.S. Shadchnev, the lower boundary with the Vardashat Fm is normal-stratigraphic

Upper contact

Conformably overlain by the Padask Fm.

Regional extent

Eastern part of the southern slope of the Turkestan Range.

GeoJSON

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Fossils

In the shales (lower part of the section) Graptolites (Along Oybadamsay) - *Climacograptus normalis* (Lapw.), *C. tuberculatus* Elles. et Wood., *Akidograptus acuminatus* (Nich.), *A. ascensus* Dav., *Cysrograptus vesiculosus* (Nich.), *Diplograptus modestus* Lapw., *Dimorphograptus swanstoni* (Lapw.), *Coronograptus cyphus* (Lapw.) etc., characteristic of the graptolite zones *Akidograptus acuminatus* and *Coronograptus cyphus* of the lower Llandovery. In the middle part, Graptolites of the *Demirastrites triangulatus* - *Coronograptus gregarius* zone of the middle Llandovery - *Climacograptus rectangularis* (Mc'Coy), *Glyptograptus tamariscus nikolaevi* Obut et Sob., *Pernerograptus revolutus* (Kurck.), *Demirastrites triangulatus* (Hark.) etc.; higher up, Graptolites of the *Demirastrites convolutus* - *Monograptus sedgwicki* zone of the upper middle Llandovery - *Cephalograptus cometa* (Gein.), *C. cometa extrema* (Bouč. et Přb.), *Monograptus sedgwicki* (Port.) etc.

Age

Fossil data indicates Lower-Middle Llandovery.

Age Span:

Beginning stage:

Rhuddanian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

443.07

Ending stage:

Aeronian

Fraction up in the ending stage:

1.0

Ending date (Ma):

438.59

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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