Taskazgan Formation

Taskazgan Fm

Period:

Proterozoic

Age Interval:

Upper Riphean, K7

Province:
Kyzylkum Region

Type Locality and Naming

Along the Tascazgan ridge, Tamydytau Mountains, Central Kyzylkum. Yu.A. Likhachev et al. in 1957 (266, p.15) as Lower Paleozoic, subsequent geological works have significantly refined and revised the extent and age (7; 16; 19; 73; 75; 165; 474).

Synonym: Taskazgan Suite, Таскатганская св.

Lithology and Thickness

The section of the suite is predominantly represented by volcanogenic-carbonaceous-siliceous-carbonate formations. The siliceous-carbonate rocks of the suite have a chemogenic-biogenic nature and were formed on an oceanic-type crust under conditions of low water medium mobility (316; 317).

The upper part - thick-bedded, massive dolomites containing quartzite interlayers and dark cherts. Thickness 100-200 m. Total thickness of the suite 400-500m.

The lower part of the section - silvery-gray-green, dark gray, black carbonaceous-quartz, quartz-siliceous-carbonaceous, cordierite, albite-cordierite, chlorite-amphibole-albite (after tholeiitic basalts) slates, alternating with banded graphitic quartzites, microquartzites, dolomites, and limestones. Thickness 300m.

Lithology Pattern:

Dolomite

Relationships and Distribution

Lower contact

Contacts with underlying formations are tectonic.

Upper contact

Contacts with overlying formations are tectonic.

Regional extent

Central Kyzylkum, Tascazgan and Tascazgan ridges (south of Tamydytau), Auminzatau, Beltau, Jetymtau, its fragments are exposed in tectonic scales and as boulder bodies in the zone of development of younger meta-terrigenous formations. Stratotype in the area of the trigonometric point with an elevation mark of 679.3 m in the Tascazgan ridge. It is correlated with the Suvliskayskaya, Sultanbayskaya, and middle-late parts of the Kokpatassky suite.

GeoJSON

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Fossils

Carbonate rocks contain a rich complex of late Riphean organic remains: acritarchs - Leiosphaeridia crassa (Naum.), L. jacutica (Tim.), L. minutissima (Naum.), L. holtedahlii (Tim.), Chuaria">Chuaria">Chuaria">Chuaria circularis Walcott., Satka elongata Jank., Leiofusidium dubium Jank., Margominuscula rugosa Naum., Trachyhystrichosphaera aimica Herm.; filamentous microfossils - Eomycetopsis typicus (Herm.), Tortunema sibirica Herm., Taskasganica propria Abd. (ms), Brevitrichoides bashkiricus Jank., Palaeolyngbya catenata (Herm.), Polytrichoides lineatus Herm,; melanocyrilliums - Melanocyrillium hexodiadema Bloeser., M. fimbriatum Bl.; microphytolites - Osagia alveolata Schip. (ms), Ambigolamellatus horridus Z.Zhur., Nubecularites abustus Z.Zhur., Vesicularites compactus Jak., V. cf. lobatus Reitl.; kamazids - Tridiidae.

Age

From the original composition of the suite, terrigenous formations with a different genesis and younger - Paleozoic age have been removed. Along the data of P.A. Mukhin et al. (317), Z.M. Abdazimova et al. (9; 16; 1996), terrigenous sediments accumulated under an active hydrodynamic regime in areas of mudflow discharge on the continental slope. These Paleozoic deposits, as a result of tectonic movements, were spatially brought closer and combined with Precambrian ones (8). Radiological data by the lead-isochron method show the age of the dolomites of the Taskazgan Fm, containing late Riphean organic remains, 800-1300 million years (491), the same within the Riphean. M.A. Akhmedjanov et al. (73; 75) attributed the T. suite to the Upper Riphean; A.K. Bukharin et al. (122) included in the composition of the suite, and meta-terrigenous rocks of the lower part of the Besapan Fm (now Kurgantau Fm) suite, and crystalline slates of the Dzhurtau Fm (in the understanding of 9; 17; 79; 165; 317; 460). The age is considered in the interval of Cambrian-middle Ordovician; on the geological map of Central Kyzylkum m-1:100000 (Aysanov et al., 1986), the suite is attributed to the Upper Riphean-Vendian; Z.M. Abdazimova et al. (9; 16; 17; 19), V.S. Korsakov et al. (236) and in the monograph (165) determine the age of the suite as late Precambrian-late Riphean; on the State Geological Map -500 of Uzbekistan (460) - middle-late Riphean.

Age Span:

Beginning stage:

Ediacaran

Fraction up in beginning stage:

0.0

Beginning date (Ma):

635.00

Ending stage:

Ediacaran

Fraction up in the ending stage:

0.5

Ending date (Ma):

586.90

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)”