Alkarakin Formation

Alkarakin Fm

Period:

Carboniferous

Age Interval:

Middle-Upper Carboniferous (?), F10a

Province:
Fergana

Type Locality and Naming

Along the Alkakara Mountains, South Fergana. G.S. Porshnyakov, A.D. Miklouho-Maclay, 1954 (355, p. 130) as conglomerates of the "Alkakara" mountains, and later as an independent sv. V.I. Dolmatov in 1962 (460, p. 209).

Synonym: Alkakarin Thickness, Алкаракинская т., Alkarakin Beds

Lithology and Thickness

In the lower part - large pebble and boulder conglomerates, gravelites with layers of sandstones and clay slates; in the upper part - rhythmically alternating gravelites, sandstones, siltstone (aleurolites). Thickness 300-400, sometimes 700m.

Lithology Pattern:

Aus Conglomerate

Relationships and Distribution

Lower contact

It lies with a sharp unconformity on terrigenous rocks of the Silurian-Lower Devonian

Upper contact

Overlying formations are unknown.

Regional extent

South Fergana, northern low foothills of the Alai Ridge from the left bank of the Shahimardan River to the Isfayram River.

GeoJSON

null

Fossils

In fragments and pebbles, organic remains of Silurian, Devonian, Carboniferous age up to the Visean age inclusive.

Age

The age is conditionally accepted as Middle-Late Carboniferous based on the similarity with Upper Paleozoic conglomeratic thicknesses (Kunya-Kul, Shan-Kul conglomerates, etc.) (459). M.B. Orlovsky and B.V. Poarkov (340) attributed it to the Carboniferous; in the Strat. sl. (441) - Devon-Lower Carboniferous; in 1976, B.D. Bolgar and M.G. Prikhodko identified it as a t., on the State Geol. Map-500 of Uzbekistan (460) - Middle-Upper Carboniferous.

Age Span:

Beginning stage:

Serpukhovian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

330.34

Ending stage:

Gzhelian

Fraction up in the ending stage:

1.0

Ending date (Ma):

298.89

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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