Cenozoic

Cretaceous

Jurassic

Triassic

Permian

Carboniferous

Devonian

Silurian

Ordovician

Cambrian

Neoproterozoic

Main source = Baratov, R.B., et al. (1976). Subdivisions of stratified and intrusive rocks of Tajikistan. Publishing House "Donish", Dushanbe, 269 pp. plus tables. Provided by Dr. Jovid Aminov, Nazarbayev University, Astana, Kazakhstan Translated to English by the GeoGPT group, Zhejiang Lab, Hangzhou, China--see About

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Kuhimalek Formation

Kuhimalek Fm

Period:

Jurassic

Age Interval:

Bathonian, S4

Province:
North Tajik

Type Locality and Naming

Synonym: Kuhimalekskaya suite, Кухималекская свита

Reference section:

Lithology and Thickness

It consists of variegated often striped fine- to medium-grained quartz sandstones, alternating with siltstones and claystones. In the upper part of the suite, there are horizons bodies of gravelites and coarse-gravel conglomerates. At the tops of this sequence, the author has for the first time discovered a layer of carbonate rocks - nodular limestones, marls, and limestone sandstones. The thickness of the sequence is 160 - 180 m.

Lithology Pattern:

Fine-grained sandstone

Relationships and Distribution

Lower contact

The considered deposits lie either sharply unconformably on the rocks of the Paleozoic, or with a slight erosion on the formations of the Ravat Fm, previously attributed to the Upper Triassic deposits, and according to our and R.Z. Gengkina's data, included in the Lower Lias section.

Upper contact

The Jurassic stratum is overlain by Cretaceous red beds with an unclear contact.

Regional extent

In the valleys of the rivers Fandarya, Pasrud, Yagnob, the section of the coal-bearing Lower-Middle Jurassic deposits - J₁₊₂is subdivided into a number of suites identified by T.A. Sixtel (Decisions..., 1959): Fand, Kukhiraat, Gabirut, Dzhizhikrut, Kukhimalek.

GeoJSON

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Fossils

At the tops of this sequence, the author has for the first time discovered a layer of carbonate rocks - nodular limestones, marls, and limestone sandstones, in which remains of bivalve molluscs (determined by N. D. Yushina) Protocardia cf. concinna (Buch.), Plesiocyprina gissarensis Rep., Modiolus sp., Camptonectes sp. indet., of the Callovian-Oxfordian age, have been identified.

Age

Until now, the age of the Kuhimalek Fm sequence has been conditionally determined as Middle Jurassic, Bathonian (?). The identified flora does not determine the age of the section. According to palynological data by E. N. Dubrovskaya (Explanatory Note..., 1971), the complex of spores and pollen extracted from the middle part of the sequence corresponds to the alleged Bathonian age. All researchers have limited the Jurassic section of Yagnob and Pasrud to the Middle Jurassic. Above, erosion was depicted. The new data change this viewpoint. However, they are not taken into account in the legend of the geological map and are published for the first time.

Age Span:

Beginning stage:

Bathonian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

168.17

Ending stage:

Bathonian

Fraction up in the ending stage:

0.4

Ending date (Ma):

167.02

Depositional setting

Depositional pattern:

Additional Information

Compiler:

Extracted from Baratov, R. B. (1976). Subdivisions of stratified and intrusive rocks of Tajikistan. Donish, Dushanbe, 276.