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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Obigarm Formation

Obigarm Fm

Period:

Cretaceous

Age Interval:

Middle Aptian (K₂¹), K1, D1, S3, C2, C2a

Province:
SW Tajik, North Tajik, Central W Tajik

Type Locality and Naming

Includes in Khation Region, Darvaz district, Dushanbe - west Shirkent-Luchob, Dushanbe - east Shirkent-Luchob.

The Berriasian? stage - middle substage of the Aptian stage is identified in the South Gissar, Dushan, Binsky, Kafirnigan, Vakhsh, Zaalaysky, and Darvaz districts includes the following horizons: 1-Karabil (Berriasian? Valanginian?); 2-Almurad (Valanginian-lower? Hauterivian); 3-Kyzyltash (upper? Hauterivian-lower? Barremian); 4-Okozbulak (upper Barremian-lower Aptian); 5-Kaligrek (middle Aptian). The Karabil horizon includes the Karabil Fm and the lower part of the Shirk Fm. The Almurad horizon includes the upper part of the Shirk Fm, the Almurad Fm, and the Vakhsh Fm. The Kyzyltash horizon is represented by the Kyzyltash Fm. The Ouzbulazh horizon includes the Ouzbulazh Fm and the lower part of the Obigarm Fm. The Kaligrek horizon is represented by the upper part of the Obigarm suite and the Aksuy Fm.

Synonym: Kaligrek horizon, Koligrek horizon, Caligrean horizon

Lithology and Thickness

The lower part of the Obigarm Fm consists of reddish-brown clays with layers of sandstones and lenses of polymictic conglomerates. The thickness is 70-150 m. The upper part of the Obigarm Fm is formed by massive red-colored sandstones with layers of sandstone-clayey rocks. The thickness is 200 m.

Lithology Pattern:

Clayey sandstone

Relationships and Distribution

Lower contact

Overlies the Ouzbulazh Fm.

Upper contact

Overlain by the Aksuy Fm.

Regional extent

Afghan-Tajik Basin.

GeoJSON

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Fossils

In Obigarm Fm, rare freshwater and brackish-water ostracods Cypridea sp., Asciocythere tadjikistanensis Andrv are found.

Age

Lower to middle Aptian

Age Span:

Beginning stage:

Aptian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

121.40

Ending stage:

Aptian

Fraction up in the ending stage:

0.4

Ending date (Ma):

118.12

Depositional setting

Depositional pattern:

Additional Information

Compiler:

Chapman, J.B., et al. (9 co-authors), 2020. The Afghan-Tajik Basin: A composite record of sedimentary basin evolution in response to tectonics in the Pamir. Basin Research, 32(3), 525-545. https:/doi.org/10.1111/bre.12381.