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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Shahriomon Formation

Shahriomon Fm

Period:

Ordovician

Age Interval:

Middle-Late Ordovician (O_2-3), C1

Province:
Central W Tajik

Type Locality and Naming

In the Zeravshan-Gissar district, A.I. Lavrushevich considers it possible to distinguish two types of sections for sediments of this age: the Shahriomon and Zahonin types, which are connected by sections of intermediate character.

Synonym: Shahriomon formation

Reference section:

Lithology and Thickness

The layer is 340 m thick, the base of which is cut by a fault. The suite is composed of quartzitic siltstones, sandstones, conglomerates with interlayers of tuffs, acidic effusives, and limestones.

Lithology Pattern:

Sandy_claystone

Relationships and Distribution

Lower contact

The base is cut by a fault.

Upper contact

Conformably overlain by Archalyk Fm

Regional extent

In the Zeravshan-Gissar district, in the area of the Shahriomon Pass (type section)

GeoJSON

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Fossils

These deposits contain a Middle-Late Ordovician fossil complex: Triplesia mongolica Chern., Holorrhynchus giganteus Kiaer, Opsimasaphus (Nobiliasaphus) nobilis (Barr.), Synchomalonotus sp., Echinosphaerites aurantium Gyll., etc.

Age

Middle-Late Ordovician

Age Span:

Beginning stage:

Dapingian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

471.26

Ending stage:

Sandbian

Fraction up in the ending stage:

1.0

Ending date (Ma):

452.75

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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