Akkuduk Formation

Akkuduk Fm

Period:

Proterozoic

Age Interval:

Upper Riphean, K5

Province:
Kyzylkum Region

Type Locality and Naming

Along the Akkuduk quarry, S. Tamdytau, Central Kyzylkum. Sh.Sh. Sabdyushev, B.V. Yaskovich et al., 1969 (393, p. 6), in the volume of the Middle-Late Riphean.

Synonym: Akkuduk Suite, Аккудукская св.

Lithology and Thickness

Massive and layered gray, dark-gray dolomites, dolomitic limestones with interlayers of dark-brown and black cherts. Thickness does not exceed 100-120m.

Lithology Pattern:

Dolomite

Relationships and Distribution

Lower contact

Schematic stratigraphic column indicates the lower contact as Uchkuduktau Fm

Upper contact

Schematic stratigraphic column indicates the upper contact as Kurgantau Fm

Regional extent

Exposed as tectonic plates, scales, and blocks on the western and eastern slopes of the Tamdytau Mountains. It is correlated with the upper parts of the Tascazgan Fm and Kokpatas Fm, Bogambir Fm and Bozdontau Fm.

GeoJSON

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Fossils

Complex of microfossils (acritarchs, filamentous) - *Chuaria">Chuaria">Chuaria">Chuaria circularis* Wal., *Margominuscula rugosa* Naum., *Leiosphaeridia jacutica* (Tim.), *L. crassa* (Naum.), *Satka elongata* Jank., *Arctacellularia ellipsoidea* Herm., *Eomycetopsis typicus* (Herm.), *Tortunema sibirica* Herm., and others; microphytoliths - *Nubecularites antis* Z.Zhur., *Osagia tenuilamellata* Reitl., *O. cf. corticosa* Nar., *Ambigolamellatus horridus* Z.Zhur., and others.

Age

The Late Riphean age is established by a complex of microfossils. Previous researchers included terrigenous rocks of the Taiman Fm of a younger Paleozoic age, attributing them to the Precambrian (73; 393), increasing its thickness to 800-1000m or dating it conditionally as Early-Middle Ordovician (122). Z.M. Abdazimova et al. (22) accept the Akkuduk Fm in the interval of only siliceous-carbonate microphytolith-containing deposits of the Late Proterozoic with a thickness of no more than 100-120m, excluding from its composition genetically distinct from chemogenic-biogenic rocks of the Akkuduk Fm, sandy-slate rocks of the Ordovician. M.A. Akhmedjanov, R.V. Choi, et al. (79) considered the age of these siliceous-carbonate deposits to be Late Proterozoic. Z.M. Abdazimova et al. (16; 17), V.S. Korsakov et al. (236) based on the complex of organic remains of the Akkuduk Fm, attribute it to the Late Riphean. It is described with the same age in the monograph (165) and is given on the State Geological Map-500 of Uzbekistan (460).

Age Span:

Beginning stage:

Tonian

Fraction up in beginning stage:

0.7

Beginning date (Ma):

804.00

Ending stage:

Cryogenian

Fraction up in the ending stage:

1.0

Ending date (Ma):

635.00

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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