Zakhkuduk Formation

Zakhkuduk Fm

Period:

Carboniferous

Age Interval:

Moscovian, K8

Province:
Kyzylkum Region

Type Locality and Naming

Along the Zakhkuduk column, southwestern part of Auminzatau, Central Kyzylkum. A.V. Tolokonnikov et al., 1984. Stratotype is the same.

Synonym: Zakhkhuduk Suite, Захкудукская св.

Lithology and Thickness

According to lithological features, A.V. Tolokonnikov et al. divide it into five packages (base to top).

1. Siltstones with rare layers of fine-grained sandstones. Thickness 300m.

2. Mica-siliceous shales, interbedded with siltstones containing layers of volcanomictic sandstones, tuff-gravels; in the upper part, bodies of volcanogenic rocks are located, represented by lavas of intermediate composition and quartz microdiorites. Thickness 60-70m.

3. Silt-pelites, shales, bluish-gray sandstones with layers and nodules of siliceous rocks; in the upper part, among the silt-pelite material, various-sized and composition pebbles, boulders of sandstones, tuff-gravels, quartz, volcanic glass of intermediate and acidic composition, cherts, less carbonate rocks are observed. Thickness 180m.

4. At the base, tuff-gravels and tuff-sandstones with single layers of dark cherts. Thickness about 50 m; in the upper part - a horizon (olistolake?) of light gray to white marbles, Thickness 5-10m. In the direction to the east, their thickness increases to 250-300 m.

Lithology Pattern:

Aus Conglomerate

Relationships and Distribution

Lower contact

Contacts with surrounding rocks are tectonic.

Upper contact

Contacts with surrounding rocks are tectonic.

Regional extent

Central Kyzylkum, southern slope of the southwestern end of the Auminzatau Mountains. The structure of the section (presence of pebbles, boulders, large horizons among fine-grained material) suggests an olistostromal nature of Zakhkhuduk Fm.

GeoJSON

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Fossils

In carbonate rocks, crinoids - Desmidocrinus parvus Schew., Podoliocrinus sp., Decacrinus ornatus Stuk. and others

Age

Crinoids determines the age of the enclosing rocks - late Silurian - early Devonian. Based on its comparison with olistostromal thicknesses of other regions, it is attributed to early Moscovian formations of the middle Carboniferous (460). A.V. Tolokonnikov et al. (1984) conditionally attributed it to the upper Silurian - lower Devonian.

Age Span:

Beginning stage:

Moscovian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

315.15

Ending stage:

Moscovian

Fraction up in the ending stage:

0.3

Ending date (Ma):

312.71

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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