Yakhak Formation

Yakhak Fm

Period:

Carboniferous

Age Interval:

Bashkirian, CK3

Province:
Chatkal-Kuramin Region

Type Locality and Naming

Along the Yakhak Pass, Ugam Range. A.S. Pitinova, 1965 (457, pp. 267-268). Stratotype in the upper reaches of Yakhaksay, near the Yakhak Pass.

Synonym: Yakhak Suite, Яхакская св.

Lithology and Thickness

Thick-bedded organogenic, organogenic-detrital, nodular-algal, oolitic limestones. In places, in the upper part, layers of conglomeratic and sandy limestones, argillites up to 300 m.

Lithology Pattern:

Oolitic limestone

Relationships and Distribution

Lower contact

Conformably overlies the Navalian Fm (upper part of the Seslavin Fm)

Upper contact

It is conformably overlain by the Upper Ugam Fm. (Tkachev et al., 1996, 460).

Regional extent

Ugam Range.

GeoJSON

null

Fossils

Contains brachiopods Choristites bisulcatiformis Sem., C. pseudobisulcatiformis Rot., C. moelleri (Jan.); foraminifers - Eostaffella compressa Brazh., Millerella umbilicata Kir, Pseudostaffella antiqua (Dutk.); ammonoids - Cancelloceras ex gr. cancellatum (Bis.).

Age

Bashkirian Stage, Lower Substage

Age Span:

Beginning stage:

Bashkirian

Fraction up in beginning stage:

0.2

Beginning date (Ma):

321.75

Ending stage:

Bashkirian

Fraction up in the ending stage:

0.3

Ending date (Ma):

320.93

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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