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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

Koytash Formation

Koytash Fm

Period:

Carboniferous

Age Interval:

Lower Moscovian, N1, N2

Province:
Nuratau

Type Locality and Naming

Along the Koytash Mountains, southern slope of the N. Nuratau Ridge, M.N. Solovyova, 1959 (382, p. 74). Stratotype on the south. slope of the Koytash mountains along the Savryuksai River.

Synonym: Koytashskaya Suite, Койташская св.

Lithology and Thickness

Detrital and biomorphic limestones, less often micritic, nodular, conglomeratic, clayey, and sludge-like, with algal bioherms, sometimes limestone conglomerates or sandstones with lenses of conglomerates and an aluminous horizon at the base. Thickness 10-100m.

Lithology Pattern:

Reef limestone

Relationships and Distribution

Lower contact

Stratigraphically unconformably overlies the Narvan Fm - the unconformity is expressed by the absence of the lower part (Kokchin Fm) of the Moscovian horizon and the formation of bauxite-like (aluminous) rocks, which are considered as the product of re-deposition of the weathering crust into the marine basin.

Upper contact

Conformably overlain by the Mikhin Fm.

Regional extent

South. slope of the North Nuratau - Koytash, Merishkor, Shokhetau mountains, north. slope - Mikhin-Daristanskaya depression, middle course of the Sentab-Hodrat interfluve.

GeoJSON

null

Fossils

Two foraminiferal complexes are distinguished. The Lower corresponds to the Aljutovella priscoidea zone, including Eostaffella acutissima Kir., E. mutabilis Raus., Schubertella obscura Lee et Chen, Fusiella praecursor paraventricosus Raus., Neostaffella umbilicata (Putrja et Leont.), Ozawainella ex gr. mosquensis Raus., Ovatella ovata (Raus.), O. constans (Saf.), Profusulinella fusiformis (Sol.), P. nuratovensis Sol. ms, Depratina prisca (Depr.), D. paratimanica (Raus.), Aljutovella aljutovica Raus., A. saratovica Putrja et Leont., A. postaljutovica Saf., Priscoidella priscoidea (Raus.), P. znensis (Raus.), Taitzechoella prolibrovitchi (Raus.), Dagmarella prima Sol., Hemifusulina dutkevichi (Putrja), H. volgensis (Putrja et Leont.), Eofusulina triangula (Raus. et Bel.). The Upper complex, less widespread, characterizes the Moellerites cylindricus-Fusulinella subpulchra zone. It differs from the lower by a sharp decrease in the number of species among profusulinellas and aljutovellas, the appearance of Pulchrella subpulchra (Putrja), P. eopulchra (Raus.) and the first representatives of Beedeininae. Among brachiopods - Choristites mosquensis Fisch., C. pavlovi Stuck., C. priscus Eichw., C. veberi Frcks., C. myatschkovensis Frcks. Calcareous algae are represented by red - Epistacheoceras sp., Stacheoides cf. tenuis Pet. et Mamet., Ungdarella uralica Masl., Pseudokomia sp., Cuneiphychus texana Johnson, green Paleoberesella cf. lahuseni (Moell.), Beresella polyramosa Kulik., Uraloporella variabilis Korde, Dvinella (Trinodella) bifurkata Masl. et Kulik., D. comata Chvorova. (Bensh et al., 1999).

Age

The Koytash Fm in the this volume was included in the schemes of 1959 and 1969 and all subsequent publications (106; 108; 110; 165; 166; 424; 439). However, in geological practice, under the name of the Koytash Fm, not only the Lower Moscovian, but also the underlying Bashkirian deposits of the Narvan Fm are often mapped (460).

Age Span:

Beginning stage:

Moscovian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

315.15

Ending stage:

Moscovian

Fraction up in the ending stage:

0.3

Ending date (Ma):

312.71

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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