Akchin Formation

Akchin Fm

Period:

Carboniferous

Age Interval:

Moscovian, CK8, CK9

Province:
Chatkal-Kuramin Region

Type Locality and Naming

Along the Akcha River, Chatkal Range. E.A. Kochnev in 1939 (131, p. 93). Stratotype along the Akcha River. In Karamazar, V.N. Baykov and V.V. Mikhailov (1968) described it as the Jamansay Fm (165; 166; 460).

Synonym: Akchinskaya Suite, Акчинская св.

Lithology and Thickness

Thick (up to 600m) uniform covers of ignimbrites and tuffs of dacitic, andesidacitic, and in the upper part (Utkemsu River valley) rhyodacitic and rhyolitic composition. At the base of the cover - often basal layers of conglomerates, conglo-breccias, gravels, and polymictic sandstones. In the southwestern spurs of the Chatkal Range, Along Y.Kh. Akhmedulin, the suite includes trachyandesites and andesites. M. from 100 m to 1300 m. In the Strat. Sl. (439) it is indicated as M. over 2000m.

Lithology Pattern:

Volcanic_ash

Relationships and Distribution

Lower contact

With erosion it lies on the Bolgalin Fm (Chashlyn Fm)

Upper contact

With erosion covers the conglomerates at the base of the Nadakskaya and Shurabsayskaya suites.

Regional extent

Chatkal, Kuramin Ranges: volcano-tectonic grabens - Almalyk, Altyn-Topkan, Kurusay-Dzhangalyk, Shavaz-Dukent, margins of the Lashkerek and Adrasman depressions.

GeoJSON

null

Fossils

No organic remains

Age

The Moscovian age is established by stratigraphic position.

Age Span:

Beginning stage:

Moscovian

Fraction up in beginning stage:

0.5

Beginning date (Ma):

311.09

Ending stage:

Moscovian

Fraction up in the ending stage:

0.9

Ending date (Ma):

307.83

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)”