Severo-Chatkal Formation

Severo-Chatkal Fm

Period:

Ordovician

Age Interval:

Lower-Middle Ordovician, CK4

Province:
Chatkal-Kuramin Region

Type Locality and Naming

In the northern part of the Chatkal Range, Kyrgyzstan. Yu V Zhukov, 1965 (200, p.39), identified on the territory of Uzbekistan by A.I. Kim in 1990.

Synonym: Severochatkalskaya Suite, Северочаткальская св.

Lithology and Thickness

The suite is predominantly composed of thin-banded cherty rocks of jasper-like appearance, red, green, and black in color, cherty-clayey and clayey slates with rare layers of tuffs of basic rocks. Thickness 100m.

Lithology Pattern:

Chert

Relationships and Distribution

Lower contact

On the right bank of the Karakarum stream, the suite conformably overlies the Sandalash Fm

Upper contact

It is overlain with local erosion by the Beshtor Fm

Regional extent

Sandalash Range - valley of the Karakarum River. It corresponds to the upper part of the Sandalash Fm.

GeoJSON

null

Fossils

It contains conodonts of the Arenig in the lower part - Paracordylodus gracilis Lind., P. parallelus Pand., Amorphognathodus? sp. and others. Ordovician radiolarians are present in the cherty rocks. However, in the upper reaches of the Chatkal River, in the underlying carbonate-slate part of the Sandalash suite (437), Middle Ordovician graptolites are present.

Age

Based on the fossil data, the S. suite is assigned to the Lower-Middle Ordovician. In the upper reaches of the Chatkal River, in the underlying carbonate-slate part of the Sandalash Fm, Middle Ordovician graptolites are present, this indicates that in some areas, the S. suite cannot be older than the Middle Ordovician.

Age Span:

Beginning stage:

Tremadocian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

486.85

Ending stage:

Dapingian

Fraction up in the ending stage:

1.0

Ending date (Ma):

469.42

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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