Cenozoic

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Jurassic

Triassic

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Carboniferous

Devonian

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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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Sumasar Formation

Sumasar Fm

Period:

Paleogene

Age Interval:

Lower Oligocene, S2, S3

Province:
North Tajik

Type Locality and Naming

Includes in Fergana Valley, Isfara River

Synonym: Sumasar Fm, Sumasar layers, Сумсарские слои

Reference section:

Lithology and Thickness

In Alai-Fergana basin, it is reddish-brown mudstones and grey sandstones rich in oysters and other bivalves, shark teeth; 0 - 70m.

Clays with interlayers of claystones and sandstones. In the Kafirnigan region, the Sumasar layers are composed of brown and cherry-colored clays with interlayers of claystones and sandstones. The thickness ranges from a few meters to 40.

In the Vakhsh and Zaalaik regions, the Sumasar layers are composed of brown and reddish clays with rare interlayers of greenish-gray claystones and sandstones. The thickness in the Vakhsh region is 5-100 m, in the Zaalaik 20-60 m.

Lithology Pattern:

Sandy claystone

Relationships and Distribution

Lower contact

Khanabad Fm

Upper contact

Shurysay-Fergna Fm

Regional extent

Sumsar Fm in the South Gissar and Dushanbe regions are not distinguished. Most likely, they are eroded. In most of the territory of the Kafirnigan region, the Sumsar layers are eroded. They are traced only on the extreme southeast of this region.

GeoJSON

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Fossils

In Alai-Fergana basin, it is rich in oysters and other bivalves, shark teeth

Among the forms of the Sumsar layers, the oysters Gryphaea sewerzowi Rom., Ostrea pigmaea Vial., commonly occur together with Nuculana crisyata Koen., Tellina praepostera Koen., T. eliptica Koen., Solen rimosus Bell., Laevicardium cingulatum Goldf., Pitar delata Koen., Cassidaria formosa Luk., Ficus crassistria Koen., as well as Cibicides macrurus N. Byk. and Cibicides subbotinae N. Byk.

Age

There is no consensus regarding the stratigraphic position of the Sumsar layers. Some researchers attribute them to the upper Eocene (Kreydenkov, Davidzon, 1966; Salibaev, 1971), others to the lower Oligocene (Davidzon, 1970).

Age Span:

Beginning stage:

Rupelian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

33.90

Ending stage:

Rupelian

Fraction up in the ending stage:

1.0

Ending date (Ma):

27.29

Depositional setting

Depositional pattern:

Additional Information

Compiler:

Bosboom, R., Mandic, O., Dupont‐Nivet, G., Proust, J. N., Ormukov, C., & Aminov, J. (2017). Late Eocene palaeogeography of the proto‐Paratethys Sea in Central Asia (NW China, southern Kyrgyzstan and SW Tajikistan). Geological Society, London, Special Publications, 427, 565–588. https://doi.org/10.1144/SP427.11.

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