Chimbay Formation

Chimbay Fm

Period:

Cretaceous

Age Interval:

upper Hauterivian-lower Aptian, U2

Province:
Ustyurt-Sultanuzdag

Type Locality and Naming

By the village of Chimbay, South Pre-Aral. V.N. Polyakov, Yu.N. Andreyev, M.S. Rodovilsky, E.M. Shvetsova, 1969 (363, p.52).

Synonym: Chimbay Suite, Чимбайская св.

Lithology and Thickness

Divided into lower and upper sub-suites.

Upper sub-suite - red, gray, greenish-gray, spotted clays, siltstone (aleurolites), sandstones with layers and lenses of gravelites and conglomerates. Thickness 20-256m.

Lower sub-suite - red-brown clays with rare blue and gray-green spots, siltstone (aleurolites), sandstones with layers of gravelites and conglomerates, which predominate near denudation areas (well 5 P - Nukus, 1 P Khodzheli). Thickness 30-263m.

Lithology Pattern:

Claystone

Relationships and Distribution

Lower contact

The suite lies conformably or with traces of erosion on the Aibugir Fm, or on the Jurassic, or on the Paleozoic. Schematic stratigraphic column shows Borehole Sandy-siltstone Fm

Upper contact

It is overlain conformably by the Khodzheilin Fm

Regional extent

Eastern Ustyurt, South Pre-Aral. Wells. Stratotype by well 2 Chimbay.

GeoJSON

null

Fossils

The suite contains in the lower sub-suite ostracods - Cypridea cf. karatajgysensis Lüb., Rhinocypris cf. echinata Lüb., in the upper foraminifers - Milliolina kuznetzovae S. Mam., Trocholina ex gr. burlini Gorb., Ammobaculites Inaequalis Tair., Gaudryina grandis (Crespin), Lenticulina karpovae (Nikit.); ostracods - Protocythere costata Andrv., Cypridea unicostata Gal., C. koskulensis Mand., C. tuberculisherga Gal., Lycopterocypris indagis Mand., L. infantilis Lüb., Darvinulina contracta Mand. In the lower and upper sub-suites, the composition of spores and pollen Collavisporites aequatorialis (Krutzsch.) Fok. (0-1), Pilosisporites setiferus (Verb.) Shv. (1-2), Clavifera triplex Bolch. (0-1), Gnetaceaepollenites spp. (3-8), Classopallis spp. (50-77).

Age

It belongs to the upper Hauterivian - lower Aptian; according to A.A. and the Decision ... , 1977 (363; 383), - to the upper Hauterivian-Barremian; in the Strat. Sl. (446) - to the Hauterivian - Barremian.

Age Span:

Beginning stage:

Hauterivian

Fraction up in beginning stage:

0.7

Beginning date (Ma):

128.33

Ending stage:

Aptian

Fraction up in the ending stage:

0.2

Ending date (Ma):

119.76

Depositional setting

Depositional pattern:

Additional Information

Compiler:

I.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)”