Kokpatas Formation

Kokpatas Fm

Period:

Proterozoic

Age Interval:

Middle-Upper Riphean, K3

Province:
Kyzylkum Region

Type Locality and Naming

Named after the town of Kokpatas, South Bukantau, Central Kyzylkum.

Synonym: Kokpatasskaya Suite, Ходжаахметская св.

Lithology and Thickness

The upper part of the section consists of gray and dark gray layered and massive dolomites and dolomitic limestones with layers and lenses of dark cherts. Thickness 100-250 m.

The lower part of the section consists of dark gray quartzites, microquartzites, and graphitic-mica schists containing lenzes and layers of dolomites, limestones, and metabasalts. Thickness up to 100 m. The total thickness of the suite is about 350 m.

Lithology Pattern:

Dolomitic limestone

Relationships and Distribution

Lower contact

The relationships with the overlying and underlying formations are tectonic.

Upper contact

The relationships with the overlying and underlying formations are tectonic.

Regional extent

Central Kyzylkum, Altyntau, Kaskyrtau, Kokpatas, Turbay mountains, small fragments of it are found as tectonic packets, blocks, and boulders among younger Paleozoic formations. The lectostratotype of the lower part of the suite is in the area of the Sarapan quarry along the Trynamasai, the upper part - in the basin of the Kokpatassaya (13). The middle and upper parts of the Kokpatas Fm are lithological and age analogs of the Tascazgan Fm, Suvliksa Fmy, and Sultanbay Fm, while the very upper part of the suite is correlated with the Bogambir Fm.

GeoJSON

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Fossils

The Late Riphean age is established by a complex of organic remains, represented by microphytoliths - Nubecularites uniformis Z.Zhur., Osagia alveolata Schip (ms), O. columnata Reitl., O. tenuilamellata Reitl., O. nimia Z.Zhur., Volvatella zonalis Z.Zhur., Glebosites gentilis Z.Zhur., Ambigolamellatus horridus Z.Zhur., Vermiculites angularis Reitl., V. tortuosus Reitl., Vermicularites flexuosus Reitl.; nevlandiids - Clathristroma sp.; camasiids Tridiidae, Caryschia drevis Sosn. (ms); saralinskids - Incertadia lamellifera aberr. arcuata Sosn.; acritarchs - Leiosphaeridia crassa (Naum.), L. holtedahlii (Tim.), Trachyhystrichosphaera parva Nich.

In the carbonate varieties, there are Middle Riphean nevlandiids - Newlandia aff. subtila Krasn., Newlandia sp.; Middle-Upper Riphean phytoderivatives - Camasiella problematica Posp. and microphytoliths - Vesicularites aff. compactus Jak., Vesicularites sp.

Age

S.A. Kushnary was assigned to the Silurian in 1939 based on its geological position. Subsequent works by M.A. Akhmedjanov, E.R. Bazarkbaev (74, p.82), R.N. Abdullaev et al. (32, pp.122-123), Z.M. Abdurazimova et al. (19, pp.100-111; 13, pp.23-27; 16, pp.3-11; 17, pp.4-15), V.S. Korsakov et al. (236, pp.3-10) significantly refined the volume of the suite and its age. Yu.A. Lichachev et al. (266) considered the suite to be Lower Paleozoic; M.A. Akhmedjanov and E.R. Bazarkbaev (74) assigned it a Late Proterozoic age for the first time based on the findings of oncoids and stromatolites, and later M.A. Akhmedjanov et al. (73; 75) - Late Riphean. I.A. Poniklanko, G.V. Bolgova et al. (1975) assigned the suite conditionally to the Riphean based on the findings of oncoids. On the geological map of Central Kyzylkum (Aysanov et al., 1986), the suite is accepted in the volume of Late Riphean-Vendian. A.K. Bukharin et al. (122) interpret the span and age of the suite differently. They include genetically different formations in the suite: terrigenous deposits of the Koksay Fm and Khodzhaakhmet Fm, amphibolites, and crystalline schists of the Cholcharatau Fm. Thickness up to 1500 m. Based on the findings of Ordovician (?) algae, they date the suite to the Cambrian-Middle Ordovician. K.K. Pyatkov et al. (1975), Z.M. Abdurazimova et al. (13; 16; 165) distinguish the Kokpatas Fm in the volume of volcanogenic-siliceous-carbonate formations of Middle-Late Riphean age. On the State Geological Map-500 of Uzbekistan (460), the suite is dated to the Middle-Late Riphean.

Age Span:

Beginning stage:

Tonian

Fraction up in beginning stage:

0.35

Beginning date (Ma):

902.00

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