Kulchalak Formation

Kulchalak Fm

Period:

Carboniferous

Age Interval:

late Visean-Serpukhovian, CK9a

Province:
Chatkal-Kuramin Region

Type Locality and Naming

Along the Kulychulak River, basin of the Almalyksay, northern slope of the Kuramin Ridge. Z.N. Kuznetsov et al., 1964; (460, p. 157). Due to insufficient clarity regarding the lower and upper boundaries of these deposits, their type section, and correlation, it is currently recommended to classify them as a formation. Previously, in the Almalyk district, the K. t. was mistakenly identified as the Mirzabad Fm of the early Tournaisian age (Kuznetsov et al., 1964; Lyashkevich et al., 1988).

Synonym: Kulchulak Topitsa, Кульчалакская т.

Lithology and Thickness

Light gray, thick-bedded to massive, sludge-detrital, organogenic limestones, partially recrystallized. In the upper parts, medium-bedded dark gray, detrital-sludge limestones with siliceous inclusions appear. In the most complete sections, Thickness up to 150 m.

Lithology Pattern:

Limestone

Relationships and Distribution

Lower contact

It is assumed to conformably overlie the Sallyatash Fm

Upper contact

The upper boundary is unclear. It is suggested that the Tashkentian t. (age equivalent of the sedimentary Dzhegirgen Fm of the early Bashkirian) may conformably overlie it.

Regional extent

Slightly in the Almalyk district; small tectonic blocks are reliably established at two points: the middle course of the Kulchulak River (Kulchulak mine area) and the right bank of the Saubulaksai, slightly north of the Aktash village.

GeoJSON

null

Fossils

Contains brachiopods Gigantoproductus ex gr. superior (Lan.), Striatifera sp.; corals - Diphyphyllum fasciculatum (Flem.), Neomultithecopora berkhy (Gors.), Arachnolasma Cylindricum Jii., conodonts - Gnathodus bilineatus bilineatus Roun., G. girtyi girtyi Hass.

Age

Age of the formation is late Visean-Serpukhovian. On the State Geological Map-500 of Uzbekistan (460), it is considered at the rank of Fm, and is attributed to the Visean-lower Serpukhovian.

Age Span:

Beginning stage:

Visean

Fraction up in beginning stage:

0.7

Beginning date (Ma):

335.26

Ending stage:

Serpukhovian

Fraction up in the ending stage:

0.1

Ending date (Ma):

329.65

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)”